Usmle neuroscience review
This presentation is the property of its rightful owner.
Sponsored Links
1 / 381

USMLE Neuroscience Review PowerPoint PPT Presentation


  • 57 Views
  • Uploaded on
  • Presentation posted in: General

USMLE Neuroscience Review. M í che á l Macken MD MRCPI Department of Neurology Northwestern University Feinberg School of Medicine.

Download Presentation

USMLE Neuroscience Review

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Usmle neuroscience review

USMLE Neuroscience Review

Mícheál Macken MD MRCPI

Department of Neurology

Northwestern University

Feinberg School of Medicine


Usmle neuroscience review

  • 72-year-old female patient with Alzheimer's disease, but no other medical problems, suddenly becomes comatose and dies due to an intracranial hemorrhage that caused severe damage to her entire left cerebral hemisphere.

  • There was no evidence or history of trauma. What is the most likely cause of this hemorrhage?

  • A. Epidural hematoma

  • B. Subdural hematoma

  • C. Amyloid angiopathy

  • D. Rupture of berry aneurysm

  • E. Rupture of Charcot-Bouchard aneurysm


The correct answer is c

The correct answer is C

  • Alzheimer's disease patients are prone to large "lobar" hemorrhages that are usually centered in the parietal lobe (thus the name "lobar") and may spread to totally destroy an entire cerebral hemisphere, resulting in death.

  • This is due to amyloid deposition into the walls of cerebral blood vessels (amyloid angiopathy), similar to the amyloid plaques seen in the parenchyma of the brain with this disease.

  • Amyloid makes these vessels weak and prone to rupture.


Usmle neuroscience review

  • Rupture of a berry aneurysm (choice D) usually causes a subarachnoid hemorrhage, in which blood leaks into the space between the arachnoid membrane and the brain. The blood may also gain access to the ventricles, but does not generally damage the cerebral hemispheres. Subarachnoid hemorrhages can be sudden and deadly, but usually present with a severe headache ("the worst headache of my life"). These aneurysms are not especially associated with Alzheimer's disease.

  • Rupture of a Charcot-Bouchard aneurysm (choice E) might cause a sudden hemorrhage within the brain causing coma and death, but it is not especially associated with Alzheimer's disease. Charcot-Bouchard aneurysms are primarily seen in patients with severe hypertension.


Epidural hematoma choice a

Epidural hematoma (choice A)

  • A collection of blood above the dura mater, usually due to a blow to the side of the head that fractures the temporal bone of the skull and shears the middle meningeal artery.

  • Even though this fast-flowing arterial blood usually causes symptoms within the first 24 hours and can cause life-threatening mass effects, no traumatic event was involved in this case.


Subdural hematoma choice b

Subdural hematoma (choice B)

  • Forms when slow-flowing venous blood collects below the dura mater due to leakage from stretched cortical veins as they drain into the superior sagittal sinus.

  • Even though it is true that Alzheimer's patients are more susceptible to these bleeds due to brain atrophy, causing cortical veins to be maximally stretched and prone to tearing, subdural hematomas are usually associated with some sort of trauma.

  • Furthermore, a subdural hematoma causes gradual symptoms over time, rather than presenting as a sudden devastating event as in this case.


Need to know

Need to know…

  • Different intracerebral hemorrhage patterns

  • ICH, SDH, Infarct, SAH, Epidural

  • Association of lobar h’age with AD


Usmle neuroscience review

  • A 20-year-old man with new onset of seizures and no history of hypertension is evaluated with a contrast-enhanced CT scan of the head, which demonstrates a mixed parenchymal and subarachnoid hemorrhage.

  • The parenchymal hemorrhage is centered over one cerebral hemisphere.

  • Which of the following is the most likely source of the hemorrhage?

  • A. Arteriovenous malformation

  • B. Berry aneurysm

  • C. Bridging vein

  • D. Charcot-Bouchard aneurysm

  • E. Middle meningeal artery


The correct answer is a

The correct answer is A.

  • Arteriovenous malformations are composed of complex tangles of congenitally malformed vessels that typically involve the superficial or deep cerebral hemispheres.

  • There is a slight male predominance, and bleeding typically occurs in adolescence or young adulthood.

  • Symptoms may be those of subarachnoid hemorrhage (headache, increased intracranial pressure) and/or seizures. Surgical resection is usually required for therapy.


Usmle neuroscience review

  • Berry aneurysms (choice B) can produce both subarachnoid and parenchymal hemorrhage, but are usually centered near the base of the brain.

  • Bleeding from bridging veins (choice C) causes subdural hematoma.

  • Charcot-Bouchard aneurysms (choice D) are small, intraparenchymal aneurysms that are related to hypertension.

  • Rupture of the middle meningeal artery (choice E) causes epidural hematoma.


Usmle neuroscience review

  • A 33-year-old woman is brought into the emergency room by ambulance. She has been on antipsychotic medications the age of 17. Physical examination reveals a well-nourished female with a temperature of 103.2 degrees F, BP of 180/99, HR of 97, and copious perspiration. She is mute, has muscular rigidity and appears to be obtunded. Which of the following is the most likely diagnosis?

  • A. Acute dystonia

  • B. Akathisia

  • C. Neuroleptic malignant syndrome

  • D. Parkinsonism

  • E. Tardive dyskinesia


The correct answer is c1

The correct answer is C

  • Neuroleptic malignant syndrome (NMS) is a potentially fatal condition that can occur at any time during the course of treatment with neuroleptics.

  • The exact etiology is unknown. Excessive muscle contraction produces muscular rigidity, and is also responsible for the high temperature.

  • The obtunded mental state and mutism is characteristic.


Neuroleptic malignant syndrome

NEUROLEPTIC MALIGNANT SYNDROME

  • Rare, life-threatening

  • Reaction to neuroleptic medication

  • All anti-psychotics may precipitate

    - typical or atypical

    - potent neuroleptics most frequent


Neuroleptic malignant syndrome1

NEUROLEPTIC MALIGNANT SYNDROME

  • Classic Symptoms

    • Fever

    • Altered Mental Status

    • Muscle Rigidity

    • Autonomic Dysfunction

  • Heterogeneous syndrome

  • Average onset 4-14 days after initiation of therapy

    • May occur at any time


Neuroleptic malignant syndrome2

NEUROLEPTIC MALIGNANT SYNDROME

  • Pathophysiology

    • Dopamine D2 receptor antagonists

    • Nigrostriatum : muscle rigidity

    • Hypothalamus : altered thermoregulation

    • Sympathetic nervous system activation or dysfunction

      • J Neurol Neurosurg Psychiatry 1995 Mar 58(3) : 271-3


Neuroleptic malignant syndrome pharmacotherapy

NEUROLEPTIC MALIGNANT SYNDROMEPHARMACOTHERAPY

  • Benzodiazepines

  • Dopamine Agonists

    • Bromocriptine

    • Levodopa/Carbidopa

    • Reverse dopamine blockade

  • Skeletal Muscle Relaxants

    • Dantrolene

      • Inhibits calcium release from sarcoplasmic reticulum

    • Neuromuscular blockade


Usmle neuroscience review

  • Extrapyramidal side effects that occur early during neuroleptic treatment include :

    • Acute dystonia (choice A, prolonged contractions of muscle groups),

    • Akathisia (choice B, "restless legs" ),

    • Parkinsonism (choice D, pill-rolling tremor and rigidity)

    • Tardive dyskinesia (choice E) is a late-appearing complication of neuroleptic therapy characterized by perioral and athetoid movements.


Usmle neuroscience review

  • A 60-year-old male executive with a history of angina pectoris and depression had bypass surgery the previous day.

  • His depression has responded well to selective serotonin reuptake inhibitors (SSRIs) and there is no history of psychosis in the past.

  • He now presents with confusion, agitation, irritability, and tries to remove his IV lines.

  • His level of consciousness fluctuates, and at times he forgets who he is.

  • He is given a neuroleptic drug, and appears much improved.

  • What is the most likely diagnosis?

  • A. Adjustment disorder

  • B. Delirium

  • C. Dementia

  • D. Exacerbation of depression with psychotic features

  • E. Schizophrenia


The correct answer is b

The correct answer is B

  • Delirium is a common complication of general anesthesia and surgery.

  • It is manifested by acute changes in mental status with waxing and waning level of consciousness, agitation, irritability, and psychosis.

  • Patients usually respond to low-dose neuroleptics to achieve sedation.

  • The course is self-limited..


Usmle neuroscience review

  • Any psychosocial or biological stressor can lead to adjustment disorder.

  • This patient's surgery will restrict his level of functioning, at least in the short term.

  • This will be difficult for a high-functioning individual to accept.

  • Adjustment disorder may present with depressive mood, anxiety, and irritability, but a fluctuating level of consciousness is not a feature of this disorder

  • Dementia (choice C) can present with irritability, confusion, and agitation, but usually has an insidious course and affects mainly cognition.

  • In contrast to delirium, it does not have a fluctuating course.


Usmle neuroscience review

  • Severe depression can present with irritability, suicidal ideation, and psychotic features (choice D). The patient has a history of depression that responded well to SSRIs and he has no prior history of psychosis. He was motivated to undergo cardiac surgery, so removing his IV lines is unlikely to be a manifestation of suicidal ideation.

  • Schizophrenia (choice E) presents with bizarre behavior, hallucinations, and delusions. It usually starts at a younger age than the acute symptoms in this patient, and is characterized by progressive deterioration in functioning. It is unlikely for a schizophrenic to achieve the functional level of an executive.


Usmle neuroscience review

  • A 38-year-old woman vacationing in Connecticut is bitten by a tick. She does not seek medical treatment and eventually develops chronic arthritis of the knee and hip joints and paralysis of the left facial muscles.

  • A physical examination during the early stages of the disorder would most likely have revealed

  • A. aphthous ulcers in the mouth

  • B. erythema chronicum migrans

  • C. flaccid paralysis of limb flexors

  • D.purpuric lesions in a bathing trunk distribution

  • E. spastic paralysis of limb extensors


The correct answer is b1

The correct answer is B

  • Lyme disease should be suspected in a patient who is bitten by a tick in the northeastern U.S. The disease is spread via a tick vector of the genus Ixodes, which transmits a spirochete that causes a systemic illness.

  • Erythema chronicum migrans is usually the first sign of the illness. This is a large red patch on the buttocks or chest that slowly expands as the center blanches.

  • Generally, patients also have constitutional symptoms, such as fever and chills, during this phase.

  • Stiff neck may develop, along with other signs of meningeal irritation, because of an aseptic meningitis.


Usmle neuroscience review

  • Complications include Bell's palsy due to involvement of branches of the facial nerve.

  • Arthritis is a prominent feature in about half the patients with Lyme disease. It tends to appear several months after the infection but may persist for several years.

  • The course of the chronic arthritis shows exacerbations and remissions; the most commonly affected joints are the knees and hips.

  • Cardiac abnormalities in Lyme disease include pericarditis and heart block.


Erythema chronicum migrans

Erythema chronicum migrans


Bells palsy

Bells palsy


Usmle neuroscience review

  • Skin manifestations do not include aphthous ulcers (choice A).

  • Flaccid or spastic paralysis of limbs (choices C and E) does not accompany Lyme disease; neurologic involvement is generally limited to cranial nerves and meningitis.

  • Purpura (choice D) is associated with vasculitis and does not occur in Lyme disease.


Usmle neuroscience review

  • What is the most important source of noradrenergic innervation to the cerebral cortex?

  • A. Basal nucleus of Meynert

  • B. Caudate nucleus

  • C. Locus coeruleus

  • D. Raphe nucleus

  • E. Substantia nigra

  • F. Ventral tegmental area


The correct answer is c2

The correct answer is C.

  • The locus coeruleus is a dense collection of neuromelanin-containing cells in the rostral pons, near the lateral edge of the floor of the fourth ventricle.

  • The fact that it appears blue-black in unstained brain tissue gave rise to its name, which means "blue spot" in Latin.

  • These cells, which contain norepinephrine, provide the majority of noradrenergic innervation to the forebrain, including the cerebral cortex.


Usmle neuroscience review

  • The basal nucleus of Meynert (choice A), a part of the substantia innominata, is a major collection of forebrain cholinergic neurons.

  • These neurons (together with neurons in septal nuclei) innervate the neocortex, hippocampal formation, and the amygdala.

  • The basal nucleus is one of the structures that degenerates in Alzheimer's disease.


Usmle neuroscience review

  • The caudate nucleus (choice B) is part of the basal ganglia, located immediately lateral to the lateral ventricles.

  • There are at least two important cell types in the caudate. GABAergic projection neurons (the majority) innervate the globus pallidus and substantia nigra pars reticulata.

  • The GABAergic neurons degenerate in Huntington's disease, which leads to enlarged lateral ventricles, clearly visible on MRI.

  • The caudate also contains cholinergic interneurons, which provide most of the acetylcholine to the striatum (caudate and putamen).

  • The balance of striatal acetylcholine and dopamine is important for the treatment of patients with extrapyramidal symptoms, such as Parkinson's disease or parkinsonism accompanying therapy with antipsychotic medications


Usmle neuroscience review

  • The raphe nuclei (choice D) are located in the midline at most levels of the brainstem. They contain serotonergic cell bodies that innervate virtually every part of the central nervous system.

  • The substantia nigra (choice E) is located in the midbrain, and consists of the substantia nigra pars compacta and the substantia nigra pars reticulata.

  • The substantia nigra pars compacta contains the nigrostriatal neurons that are the source of striatal dopamine.

  • This cell group degenerates in Parkinson's disease or in response to neurotoxic agents such as MPTP.

  • The substantia nigra pars reticulata consists predominately of GABAergic neurons that innervate the thalamus.


Usmle neuroscience review

  • The ventral tegmental area (choice F) is located in the midbrain and is an important source of dopamine for the limbic and cortical areas.

  • These cells are called mesolimbic and mesocortical neurons.

  • Overactivity of this cell group is a popular theory of the etiology of schizophrenia, and is the basis for the administration of antipsychotic agents (dopamine receptor antagonists


Anatomy transmitters diseases

Anatomy, Transmitters, Diseases

  • Locus CoeruleusNoradrenalinDepression

  • B. Nuc MeynertAcetylcholineAlz D

  • Raphe nucleiSerotoninDepression

  • Sub NigraDopaminePark D

  • CaudateGABAHunt D

  • Ventral tegmentalDopamineSchizoph.


Usmle neuroscience review

  • A 67-year-old male smoker presents to his physician for a routine physical examination. Chest x-ray demonstrates a 2-cm density on the left side. Laboratory studies are remarkable for a serum sodium of 128 mEq/L. The findings may be attributable to tumor cell secretion of

  • A. adrenocorticotrophic hormone (ACTH)

  • B. antidiuretic hormone (ADH)

  • C. melanocyte-stimulating hormone (MSH)

  • D. parathyroid hormone (PTH)

  • E. vasoactive intestinal polypeptide (VIP)


The correct answer is b2

The correct answer is B.

  • All of the hormones listed can be secreted by bronchogenic carcinoma, and may cause a paraneoplastic syndrome. Of the answer choices provided, only ADH (antidiuretic hormone) causes hyponatremia.

  • ACTH (choice A) causes Cushing's syndrome.

  • MSH (choice C) causes increased skin pigmentation.

  • PTH (choice D) causes hypercalcemia.

  • VIP (choice E) causes diarrhea and hypokalemia.

  • Other hormones that can be produced include human chorionic gonadotropin (hCG; gynecomastia), prolactin (lactation), and calcitonin (hypocalcemia).


Usmle neuroscience review

  • A 75-year-old woman who has not been eating because of severe gastroenteritis is admitted to the hospital. Blood chemistry demonstrates a serum sodium of 125 mEq/L. Overly vigorous correction of this electrolyte imbalance would most likely damage which of the following structures?

  • A. Cerebellum

  • B. Cortex

  • C. Pons

  • D. Spinal cord

  • E. Thalamus


The correct answer is c3

The correct answer is C

  • Central pontine myelinolysis is a specific, and nearly always iatrogenic, condition characterized by demyelination of the central pons following overly rapid correction of severe hyponatremia.

  • Axons and neuronal cell bodies are relatively preserved. The lesion usually specifically involves the basis pontis and portions of the pontine tegmentum.

  • Clinically, patients may develop a rapidly evolving para- or quadriparesis, often accompanied by pseudobulbar symptoms such as dysarthria or dysphagia.

  • The specific mechanism by which the pons is damaged is unclear.


Need to know1

Need to know…

  • Causes of hyponatremia :

  • Especially small cell lung carcinoma

  • Danger of rapid correction – CPM

  • Drugs that cause hyponatremia:-

    • Carbamazepine (Tegretol)

    • Oxcarbazepine

    • Chlorpromazine (Thorazine)

    • Diuretics

    • Vasopressin analogs

    • Indapamide (Natrilix)

    • Selective serotonin reuptake inhibitors

    • Theophylline

    • Amiodarone (Cordarone)

    • Ecstasy (3,4-methylenedioxymethamphetamine)


Usmle neuroscience review

  • A sharp instrument passing through the superior orbital fissure would most likely sever the

  • A. abducens nerve

  • B. facial nerve

  • C. mandibular nerve

  • D. maxillary nerve

  • E. middle meningeal artery

  • F. ophthalmic artery

  • G. optic nerve


The correct answer is a1

The correct answer is A.

  • Everything that innervates the eye, other than the optic nerve, passes through this fissure.

  • This includes the oculomotor nerve (CN III), the trochlear nerve (CN IV), the ophthalmic nerve (V1), and the abducens nerve (CN VI).


Usmle neuroscience review

  • The facial nerve (CN VII; choice B) passes through the internal auditory meatus.

  • The mandibular nerve (V3; choice C) passes through the foramen ovale.

  • The maxillary nerve (V2; choice D) passes through the foramen rotundum.

  • The middle meningeal artery (choice E) passes through the foramen spinosum.

  • The ophthalmic artery (choice F) passes through the optic canal.

  • The optic nerve (choice G) passes through the optic canal.


Need to know2

Need to know…

  • Foramina of skull, what travels through them:

    Orbital fissures

    OvaleMandibular -V3

    RotundumMaxillary -V2

    SpinosumMiddle meningeal Artery


Usmle neuroscience review

  • 45-year-old man presents to a physician with complaints of double vision and ptosis.

  • The patient has noticed that these problems are minor in the early morning, but become progressively more severe during the course of the day.

  • Symptoms markedly improve after a test dose of edrophonium. This condition is usually related to autoantibodies directed against which of the following?

  • A. Acetylcholine receptor

  • B. Double-stranded DNA

  • C. Neutrophil cytoplasmic proteins

  • D. SS-A (Ro)

  • E. TSH receptor


Answer a

Answer A

  • Myasthenia gravis peaks in younger women 30’speak in older men 60’s

  • Associated with thymoma:

    50% of pts with thymona have MG

    10% of pts with MG have thymona

  • Drug that causes myasthenia :Penicillamine


Usmle neuroscience review

  • 61-year-old man with a history of hypertension has a stroke.

  • He is seen in neurology clinic, where his wife states that he has been having trouble getting dressed in the morning, and notes that she has seen him shaving only the right side of his face

  • Which of the following structures did the man's stroke most likely involve?

  • A. Left frontal lobe

  • B. Left midbrain

  • C. Left parietal lobe

  • D. Right frontal lobe

  • E. Right midbrain

  • F. Right parietal lobe


The correct answer is f

The correct answer is F

  • This is an example of a sensory neglect syndrome, in this case involving the left side (the patient is still taking care of the right side).

  • This is the most common pattern in right-handed patients, and is usually due to damage to the right hemisphere, typically in the parietal lobe.


Usmle neuroscience review

  • Another symptom produced by this lesion is extinguishing to double simultaneous stimuli.

  • For example, if you touch such a patient on the left side of the face, he will be aware of it.

  • If you touch him on the right side, he will be aware of it, but if you simultaneously touch him on both the right and left sides, he will only be aware of the touch on the right.


Frontal lobe syndrome

Frontal lobe syndrome

  • Patients with lesions of the frontal lobe (choices A and D) can present with a variety of signs depending on the location of the lesion.

  • Signs and symptoms include a decrease in spontaneous behavior, social inappropriateness, an inability to deal in abstraction, difficulty changing strategies, and perseveration.


Usmle neuroscience review

  • A 54-year-old man is evaluated by a neurologist because of a gait disorder. When the physician passively moves the patient's right great toe upward or downward, the patient cannot accurately report the direction of motion, although his perception of light touch and painful stimuli is unimpaired. This finding can best be explained by a lesion of which of the following structures?

  • A. Right fasciculus cuneatus

  • B. Right fasciculus gracilis

  • C. Right lateral lemniscus

  • D. Right medial lemniscus

  • E. Right ventroposterolateral nucleus of the thalamus

  • F. Right ventroposteromedial nucleus of the thalamus


The correct answer is b3

The correct answer is B.

  • The patient's inability to detect the position of his toe reflects a lack of conscious proprioception for this part of his body.

  • Conscious proprioception, discriminative touch, and vibration sense are all carried by the dorsal column/medial lemniscus system.

  • The fact that he can still perceive light touch and painful stimuli indicates that his anterolateral system is unimpaired.

  • In the dorsal column/medial lemniscus system, the primary neuron's cell body is located in the dorsal root ganglia and sends its projection to the cord through the dorsal roots.

  • The fibers do not synapse in the cord, but rather ascend the cord in the dorsal columns.


Usmle neuroscience review

  • Fibers carrying information from the legs ascend in the fasciculus gracilis; those receiving input from the arms project in the fasciculus cuneatus.

  • Both ascend to the caudal medulla, where they terminate in the nucleus gracilis and nucleus cuneatus, respectively.

  • The secondary neurons originating from these nuclei cross as the internal arcuate fibers, ascend as the medial lemniscus, then synapse in the ventroposterolateral (VPL) nucleus of the thalamus.

  • Tertiary neurons from the VPL project to the ipsilateral somatosensory cortex.

  • Therefore, a lack of conscious proprioception from the right toe could result from lesions to the right fasciculus gracilis, the right nucleus gracilis, the left medial lemniscus, the left VPL, or left somatosensory cortex


Usmle neuroscience review

  • The right fasciculus cuneatus (choice A) carries discriminative touch, proprioception, and vibration information from the upper extremities.

  • The right lateral lemniscus (choice C), part of the auditory system, receives input from the contralateral cochlear nuclei and from the superior olivary nuclei, and projects to the inferior colliculus.

  • The right medial lemniscus (choice D) carries discriminative touch, proprioception, and vibration information from the left side of the body.

  • The right ventroposterolateral (VPL) nucleus of the thalamus (choice E) receives all sensory information (including pain and temperature information) from the left side of the body.

  • The right ventroposteromedial (VPM) nucleus of the thalamus (choice F) receives all sensory information from the left side of the face.


Usmle neuroscience review

  • A 39-year-old executive presents with a chief complaint of insomnia. He is given a prescription for pentobarbital, and uses it as prescribed to induce sleep in the evening. When he runs out of the medication he has a great deal of difficulty falling asleep. When he finally does fall asleep, he experiences a multitude of intense, colorful dreams. This is an example of:

  • A. hypnopompic hallucinations

  • B. night terrors

  • C. REM rebound

  • D. sensitization

  • E. tolerance


The correct answer is c4

The correct answer is C.

  • Barbiturates, alcohol, phenothiazines, and MAO inhibitors decrease the amount of REM sleep while the patient is taking them.

  • Withdrawal of the agent then allows the body to compensate for "missed" REM sleep, and REM rebound develops. This phenomenon is characterized by an increase in the number and intensity of dreams for several days after discontinuation of the drug in question.

  • Hypnopompic hallucinations (choice A) occur as the patient is awakening, not while in a deep sleep.

  • Night terrors (pavor nocturnus; choice B) generally occur in children, and are not characterized by vivid, colorful nightmares, as they occur in stage 4 rather than in REM sleep.


Sleep the essentials

Sleep : The essentials

  • Cycling4-5 cycles per night

  • SpindlesStage 2 sleep

  • Saw-tooth wavesREM sleep

  • REMMuscle atoniaNocturnal erectionsDreaming


Usmle neuroscience review

  • NarcolepsySleep onset REMDaytime somnolenceHypnagogic hallucinationHypnapompic hallucinationsCataplexySleep paralysis

  • REM sleep disorderLack of atonia during REM


Usmle neuroscience review

  • During an initial physical examination of a 42-year-old man, a neurologist observes that the patient has a drooping right eyelid and a dilated right pupil.

  • Which of the following neural structures is most likely affected?

  • A. Cervical sympathetic chain

  • B. Facial nerve

  • C. Oculomotor nerve

  • D. Superior cervical ganglion

  • E. Trigeminal nerve


The correct answer is c5

The correct answer is C

  • The oculomotor nerve innervates the levator palpebrae superioris, which elevates the eyelid.

  • The oculomotor nerve also contains preganglionic parasympathetic fibers that synapse, in the ciliary ganglion, on postganglionic parasympathetic nerve fibers that innervate the sphincter pupillae muscle, which constricts the pupil.

  • A lesion of the oculomotor nerve may therefore result in both drooping of the eyelid (ptosis) and dilation of the pupil (mydriasis)..


Usmle neuroscience review

  • The cervical sympathetic chain (choice A) contains preganglionic sympathetic nerve fibers, arising from the upper thoracic spinal cord, which ascend to the cervical sympathetic ganglia. A lesion of these nerves may result in Horner's syndrome, which includes a ptosis and miosis (pupillary constriction), and often, anhidrosis (lack of sweating).

  • The facial nerve (choice B) innervates the muscles of facial expression, including the orbicularis oculi muscle. A lesion of this nerve may therefore result in the inability to close the eye.


Usmle neuroscience review

  • The superior cervical ganglion (choice D) contains the cell bodies of postganglionic sympathetic nerves that innervate structures in the head. A lesion of this structure will cause Horner's syndrome.

  • The trigeminal nerve (choice E) provides sensory innervation to much of the head. A lesion of this nerve may interfere with the corneal blink reflex


Usmle neuroscience review

  • 70-year-old male patient dies with severe dementia.

  • Autopsy demonstrates marked atrophy of the frontal and temporal lobes, with relative sparing of the rest of the brain. Which of the following microscopic features would be most useful in establishing the diagnosis?

  • A. Enlarged presynaptic axon terminals surrounding a central core of extracellular amyloid-like substance

  • B. Intracytoplasmic spherules composed of paired helical filaments

  • C. Intracytoplasmic spherules that stain brightly eosinophilic

  • D. Intranuclear and intracytoplasmic inclusion bodies in enlarged cells

  • E. Small cytoplasmic vacuoles containing a central granule


The correct answer is b4

The correct answer is B.

  • Selective frontal and temporal atrophy in a demented patient suggests Pick's disease. Microscopically, severe neuronal loss and astrocytosis are seen.

  • The characteristic microscopic finding in this disorder is the presence of Pick's bodies, which are intracytoplasmic spherules composed of paired helical filaments, seen best with silver stains.


Usmle neuroscience review

  • Choice A describes senile plaques. These are seen in Alzheimer disease as well as in some normal elderly individuals.

  • Choice C describes Lewy bodies, seen in Parkinson's disease.

  • Choice D describes the inclusion bodies typically seen in glial cells and endothelial cells in cytomegalovirus encephalopathy.

  • Choice E describes granulovacuolar degeneration


Usmle neuroscience review

  • A 55-year-old man is brought to his physician's office with a 3-month history of progressive mental deterioration in the form of memory loss , mood changes, and errors in judgment.

  • His gait is unsteady, and he requires assistance to prevent falling. He has no history of seizures, head trauma, or incontinence. Computed tomography (CT) scan and lumbar puncture are unremarkable. Physical examination reveals hypertonicity of all extremities, bilateral equivocal plantar response, ataxic gait, and myoclonic jerks in the lower extremities. What is the mechanism by which this infectious agent causes its pathology?

  • A. Amyloid deposition

  • B. Autoimmune destruction

  • C. Chronic inflammation

  • D. Embolization and infarction

  • E. Toxin production


The correct answer is a2

The correct answer is A.

  • This is the classic presentation of Creutzfeldt-Jacob disease (CJD).

  • Although the pathogenesis is incompletely understood, these patients develop extracellular deposition of abnormal fibrillar proteins in the brain – prion proteins


Usmle neuroscience review

  • Autoimmune destruction (choice B) is not indicated because there is no immunologic response to the deposition of these extracellular proteins.

  • There is no chronic inflammation (choice C)

  • Although embolization and infarction (choice D) could complicate the presentation in the age group typically afflicted with CJD, these processes are not believed to have any direct role in this pathology.

  • No toxin is produced (choice E) to account for the presentation in CJD.


Usmle neuroscience review

  • A 48-year-old woman has an abnormal neurological exam.

  • An electroencephalogram is subsequently performed and reveals delta waves over her left frontal lobe.

  • Which of the following was the most likely finding on the woman's neurological exam?

  • A. Hyperreflexia on the left

  • B. Hyperreflexia on the right

  • C. Left homonymous hemianopia

  • D. Right homonymous hemianopia

  • E. Sensory deficit on the left

  • F. Sensory deficit on the right


The correct answer is b5

The correct answer is B.

  • The presence of delta waves over her left frontal lobe indicates a lesion in this region.

  • The primary motor cortex, or motor strip, is present in the frontal lobe.

  • This cortex contains cell bodies of corticospinal neurons, the majority of which project to the opposite side of the spinal cord after decussating in the medulla.

  • A lesion of these neurons prior to decussation causes upper motor neuron signs on the opposite side, including hyperreflexia and a spastic paresis.

  • Thus, a lesion to the left frontal lobe could produce a right-sided hyperreflexia.


Usmle neuroscience review

  • Hyperreflexia on the left (choice A) could be caused by a lesion of the right primary motor cortex.

  • A left homonymous hemianopia (choice C) could be caused by a lesion in the right occipital lobe.

  • A right homonymous hemianopia (choice D) could be caused by a lesion in the left occipital lobe.

  • A sensory deficit on the left (choice E) could be caused by a lesion in the right parietal lobe, where the primary sensory cortex is located.

  • A sensory deficit on the right (choice F) could be caused by a lesion in the left parietal lobe, where the primary sensory cortex is located.


Usmle neuroscience review

  • A patient arrives at the emergency department with a knife blade embedded in his gluteal region.

  • Radiographic examination reveals that the tip of the knife is against the upper border of the greater sciatic foramen.

  • Which of the following nerves is most likely to have been injured?

  • A. Inferior gluteal

  • B. Obturator

  • C. Pudendal

  • D. Sciatic

  • E. Superior gluteal


The correct answer is e

The correct answer is E.

  • Most of the greater sciatic foramen is occupied by the piriformis muscle.

  • The superior gluteal nerve, artery, and vein exit through the greater sciatic foramen above the piriformis and lie against the upper border of the foramen.

  • This nerve innervates the gluteus medius, gluteus minimus, and tensor fasciae latae muscles.


Usmle neuroscience review

  • The inferior gluteal nerve (choice A) exits through the greater sciatic foramen below the piriformis muscle and lies against the inferior border of the foramen. This nerve innervates the gluteus maximus muscle. The obturator nerve (choice B) exits through the obturator canal, an opening in the obturator membrane. This nerve innervates the muscles of the medial compartment of the thigh, the adductor longus, adductor brevis, part of the adductor magnus and the gracilis, and part of the pectineus muscle.

  • The pudendal nerve (choice C) exits through the greater sciatic foramen below the piriformis and lies against the lower border of the foramen. After entering the gluteal region briefly, the nerve passes through the lesser sciatic foramen to enter the perineum. It provides sensory and motor innervation to structures in the perineum.

  • The sciatic nerve (choice D) exits through the greater sciatic foramen below the piriformis muscle. This nerve is composed of the tibial nerve and the common peroneal nerve; it innervates muscles in the posterior compartment of the thigh and all of the muscles in the leg and foot.


Usmle neuroscience review

  • A 12-year-old male presents with a severely damaged nail on his index finger, after accidentally crushing the finger while closing a door.

  • A decision is made to excise the injured nail. In preparation for the procedure, the physician would most likely anesthetize a branch of the

  • A. anterior interosseus nerve

  • B. median nerve

  • C. musculocutaneous nerve

  • D. radial nerve

  • E. ulnar nerve


The correct answer is b6

The correct answer is B.

  • The median nerve supplies the surface of the lateral palm, the palmar surface of the first three digits and the distal dorsal surface of the index and middle fingers (including the nail beds).

  • Therefore, prior to performing surgery in this area, it is essential to anesthetize a branch of this nerve (possibly a proper digital branch) to eliminate pain sensation around the nail bed of the index finger.


Usmle neuroscience review

  • A 72-year-old woman has the abrupt onset of right-sided weakness affecting the face and arms.

  • MRI is consistent with an infarct in the territory of the middle cerebral artery. Pathologic examination of the patient's brain would likely show

  • A. caseous necrosis

  • B. coagulative necrosis

  • C. enzymatic fat necrosis

  • D. gangrenous necrosis

  • E. liquefactive necrosis


The correct answer is e1

The correct answer is E.

  • Liquefactive necrosis occurs in brain or other neural tissues and in pancreatic tissue. In this type of necrosis, the tissue appears liquefied under the microscope, without preservation of cell outlines.

  • Liquefactive necrosis can also be seen in some bacterial infections, especially those caused by pyogenic Staphylococci, Streptococci, or certain coliform bacteria.


Usmle neuroscience review

  • Caseous necrosis (choice A) is generally an indication of infection by Mycobacterium tuberculosis. The term caseous refers to the appearance of the tissue, i.e., soft, white necrotic areas that have a cheese-like appearance. Microscopically, the necrotic areas are lightly eosinophilic (stain light pink), with little or no discernible cellular detail. The eosinophilia reflects staining of residual cellular proteins.

  • Coagulative necrosis (choice B) is a more common type of necrosis, characteristic of anoxic injury and most infarcts. Cellular outlines are preserved, but proteins are denatured, and the cells stain in an eosinophilic manner.


Usmle neuroscience review

  • Enzymatic fat necrosis (choice C) is seen primarily with pancreatic injury when pancreatic lipases are released and digest fat to form free fatty acids. These fatty acids complex with calcium, resulting in the production of calcium soaps (saponification) in the pancreatic tissue or in extrapancreatic fatty tissues (eg, omentum).

  • In gangrene (choice D), bacterial infection is superimposed on a background of massive necrosis and putrefaction


Usmle neuroscience review

  • A patient arrives in the emergency room after having suffered severe head trauma in a motorcycle accident.

  • Radiographic studies of the head reveal a basilar skull fracture in the region of the foramen ovale. Which of the following functional losses would most likely be related to this injury?

  • A. Loss of abduction of the eye

  • B. Loss of sensation over the forehead

  • C. Loss of sensation over the zygoma

  • D. Loss of taste sensation on the anterior 2/3 of the tongue

  • E. Paralysis of muscles of mastication


The answer is c

The answer is C

  • Maxillary division of trigeminal V2


Usmle neuroscience review

  • A 12-year-old is seen by a pediatrician for a severe sore throat. Physical examination reveals a brightly erythematous patch in the upper posterior pharynx.

  • Which of the following cranial nerves would most likely carry the pain sensation associated with this lesion?

  • A. III

  • B. V

  • C. VII

  • D. IX

  • E. X


The correct answer is d

The correct answer is D.

  • The glossopharyngeal nerve (IX) carries general somatic sensation from the posterior part of the upper pharynx, eustachian tube, and posterior one-third of the tongue.

  • It also carries taste sensation from the posterior one-third of the tongue, and conveys afferent fibers from the carotid sinus baroreceptors and carotid body chemoreceptors, and efferent fibers to the stylopharyngeus muscle.


Usmle neuroscience review

  • The oculomotor nerve (III, choice A) supplies the extraocular muscles (superior, inferior, and medial recti, and inferior oblique) and levator palpebrae superioris muscle, and sends parasympathetic fibers to the ciliary muscle and iris.

  • The trigeminal nerve (V, choice B) receives somatic sensation information from the face, lips, gums, teeth, palate, and anterior two-thirds of the tongue.


Usmle neuroscience review

  • The facial nerve (VII, choice C) carries taste sensation from the anterior two-thirds of the tongue.

  • It supplies motor innervation to the muscles of facial expression and to the stapedius muscle, and sends parasympathetic fibers to the lacrimal, submandibular, and sublingual glands.

  • The vagus nerve (X, choice E) carries sensation from the lower part of the posterior pharynx, larynx, trachea, and esophagus.

  • It supplies parasympathetic innervation to the thoracic and abdominal viscera to the left colic flexure.


Usmle neuroscience review

  • As part of a complete neurological examination, a medical student takes a cotton-tipped applicator and touches the patient's left eye with a thin wisp of cotton as the patient looks to the right.

  • The patient closes both of his eyelids in response. Which of the following cranial nerves is responsible for the motor limb of this reflex?

  • A. Abducens

  • B. Facial

  • C. Optic

  • D. Trigeminal

  • E. Trochlear


The answer is b

The answer is B

  • The corneal reflex is tested by touching the cornea of one eye with a cotton wisp; this causes both eyes to close. The afferent, or sensory, component of the corneal reflex is mediated by the ophthalmic division of the ipsilateral trigeminal nerve (V-1). The efferent, or motor, component is mediated by the facial nerve (CN VII), bilaterally.


Usmle neuroscience review

  • The abducens nerve (CN VI; choice A) innervates the lateral rectus muscles, which abduct the eyes.

  • The optic nerve (CN II; choice C) is responsible for vision, providing the afferent limb of the pupillary light reflex.

  • The trigeminal nerve (CN V; choice D) is responsible for the afferent limb of the corneal reflex. It also innervates the muscles of mastication and provides sensory innervation to the face.

  • The trochlear nerve (CN IV; choice E) innervates the superior oblique muscles, which depress, intort, and abduct the eyes.


Usmle neuroscience review

  • The facial nerve (VII, choice C) carries taste sensation from the anterior two-thirds of the tongue. It supplies motor innervation to the muscles of facial expression and to the stapedius muscle, and sends parasympathetic fibers to the lacrimal, submandibular, and sublingual glands.

  • The vagus nerve (X, choice E) carries sensation from the lower part of the posterior pharynx, larynx, trachea, and esophagus. It supplies parasympathetic innervation to the thoracic and abdominal viscera to the left colic flexure.


Reflexes

Reflexes


Usmle neuroscience review

  • A 61-year-old male is brought into the hospital by his daughter because of confusion and difficulty walking. He denies recent alcohol consumption, but admits to a 35-year history of heavy drinking.

  • Physical examination is remarkable for ataxia and a sluggish pupillary light reflex. One week later, he is calm and alert, and his gait and pupillary light reflex have returned to normal.

  • However, neuropsychological testing reveals severe short-term memory impairment and frank confabulation. Which of the following is most likely to be associated with his amnestic syndrome?

  • A. Amyloid plaques

  • B. Depletion of dopamine-producing cells in the substantia nigra

  • C. HIV infection

  • D. Neuronal Pick bodies

  • E. Hemorrhages of the mamillary bodies


The correct answer is e2

The correct answer is E.

  • This clinical case is an example of Wernicke-Korsakoff syndrome, which is caused by thiamine deficiency-usually secondary to chronic alcohol abuse.

  • The acute symptoms are referred to as Wernicke's syndrome and include confusion, ataxia, vestibular dysfunction, sluggish pupillary light reflexes, anisocoria, and oculomotor dysfunction.

  • The chronic symptoms are referred to as Korsakoff's syndrome and include anterograde amnesia and confabulation in an alert and responsive patient. Wernicke-Korsakoff is a favorite USMLE disease.


Usmle neuroscience review

  • Amyloid plaques (choice A) are seen in Alzheimer's disease. Although memory impairments are an early symptom of Alzheimer's disease, patients typically suffer from other cognitive impairments as well, such as aphasia, apraxia, agnosia, or disturbances in executive functioning.

  • Depletion of dopamine-producing cells in the substantia nigra (choice B) causes Parkinson's disease. Twenty to thirty percent of Parkinson's patients are demented, but they also present with motor abnormalities such as bradykinesia, rigidity, or tremor.

  • HIV infection (choice C) can result in a subcortical dementia, but typically, other cognitive and motor deficits are seen in addition to the amnestic syndrome.

  • Neuronal Pick bodies (choice D) are seen in Pick's disease, which causes a frontal-temporal dementia. Pick's disease is commonly characterized by marked personality and behavioral changes in addition to amnesia.

  • Features of the Kluver-Bucy syndrome (hypersexuality, hyperorality, placidity) are fairly common in patients with Pick's disease.


Usmle neuroscience review

  • A blockage of the cerebral aqueduct will produce an increase in pressure initially in the

  • A. foramen of Magendie

  • B. foramina of Luschka

  • C. fourth ventricle

  • D. interventricular foramen

  • E. lateral ventricles

  • F. subarachnoid space

  • G. third ventricle


The correct answer is g

The correct answer is G.

  • The cerebrospinal fluid (CSF) circulates through the ventricular system as follows:

  • from the lateral ventricles, through the interventricular foramen, into the third ventricle,

  • through the cerebral aqueduct (of Sylvius) to reach the fourth ventricle, and

  • out the foramina of Luschka and Magendie into the subarachnoid space.

  • Once the CSF is in the subarachnoid space, it is absorbed through arachnoid villi into dural sinuses, where it mixes with the venous blood.

  • Therefore, a blockage of the cerebral aqueduct, which connects the third and fourth ventricles, will produce an increase in pressure initially in the third ventricle.


Usmle neuroscience review

  • A 70-year-old man comes to clinical attention with progressive memory loss, urinary incontinence, and gait instability.

  • MRI of the brain shows dilatation of the ventricular cavities, while the cerebral cortex appears normal. No infarcts are seen.

  • Repeated lumbar punctures reveal occasional increases in cerebrospinal fluid (CSF) pressure. A biopsy of the frontal cortex demonstrates the absence of neurofibrillary tangles and senile plaques. Which of the following is the most appropriate treatment?

  • A. Acetylcholinesterase inhibitors such as donezepil

  • B. Aspirin

  • C. L-DOPA

  • D. Ventricular shunt

  • E. Vitamin B1 (thiamine)


Correct answer is d wet wobbly wacky

Correct answer is D WET, WOBBLY, WACKY

  • The clinical presentation has the classic triad of memory loss, urinary incontinence, and gait abnormalities characteristic of normal pressure hydrocephalus (recently renamed intermittently raised pressure hydrocephalus).

  • This condition results from intermittent increases in CSF pressure, leading to progressive damage to cerebral white matter and dilatation of the ventricles.

  • No significant cortical atrophy is present. The lack of Alzheimer-related changes in the biopsy and the measurements of CSF pressure support the diagnosis.

  • Relief of CSF pressure can be obtained by placing a ventricular shunt, which usually improves clinical symptomatology.


Cerebral atrophy

Cerebral atrophy


Usmle neuroscience review

  • Tacrine and other inhibitors of acetylcholinesterase (choice A) are used in the symptomatic therapy of Alzheimer disease.

  • The pathology of this disease includes degeneration of cerebral cholinergic systems, such as the basal nucleus of Meynert, which project to the neocortex and are involved in memory and learning.

  • Acetylcholinesterase degrades acetylcholine after release from presynaptic boutons. Acetylcholinesterase inhibitors therefore enhance the concentration of acetylcholine and amplify cholinergic neurotransmission.

  • Aspirin (choice B) is used to prevent aggregation and adhesion of platelets in patients with risk factors for cerebrovascular disease. Prophylactic aspirin treatment lowers the incidence of transient ischemic attacks and brain infarcts.


Usmle neuroscience review

  • L-DOPA (choice C) is a precursor of dopamine, the neurotransmitter of the nigrostriatal neurons that degenerate in Parkinson disease.

  • L-DOPA, especially in combination with a peripheral decarboxylase inhibitor, is therefore used in the treatment of this disorder.

  • Vitamin B1 (choice E) is used in the treatment of Wernicke encephalopathy, which is caused by thiamine deficiency.

  • If untreated, Wernicke encephalopathy progresses to Korsakoff syndrome, characterized by memory loss, confusion, and confabulation.


Usmle neuroscience review

  • A 40-year-old man develops progressive weakness culminating in paralysis. Both upper and lower motor neurons are lost in this man's disease.

  • Over the course of a decade, the disease progresses to complete paralysis of all voluntary muscles, and he dies in respiratory failure.

  • At autopsy, which CNS sites would show the most marked neuronal loss?

  • A. Caudate

  • B. Cerebellum

  • C. Globus pallidus

  • D. Spinal cord

  • E. Substantia nigra


The correct answer is d1

The correct answer is D

  • Amyotrophic lateral sclerosis (ALS) is characterized by degeneration of both upper and lower motor neurons.

  • Depending on the stage of this disease, patients may primarily experience either upper motor symptoms (hyperreflexia, spasticity, Babinski reflex) or lower motor symptoms (weakness, muscular atrophy, fasciculations).

  • The upper motor neurons are located in the motor area of the cerebral cortex; the lower motor neurons are located in the anterior horn of the spinal cord.

  • The physicist Steven Hawking has the disease.

  • There is as yet no effective therapy.


Usmle neuroscience review

  • The caudate (choice A) is damaged in Huntington disease, characterized by choreiform movements.

  • The cerebellum (choice B) is damaged in spinocerebellar degenerative diseases, including Friedreich ataxia and olivopontocerebellar atrophy, both of which have ataxia as a prominent symptom.

  • The globus pallidus (choice C) degenerates in striatonigral degeneration, which resembles Parkinson disease.

  • The substantia nigra (choice E) is damaged in Parkinson disease, characterized by tremor and difficulty initiating movements.


The correct answer is e3

The correct answer is E.

  • Rabies is still endemic in many areas of the world, including regions of Central and South America. The etiologic agent is a virus transmitted to humans by the bite of a rabid dog or other animal.

  • Exposure to vampire bats (found in Central America) may lead to infection without a bite. The disease manifests with extraordinary excitability, headache, aversion to water, convulsions, and coma.

  • In this case, the clinical information provided would not be sufficient to make a correct choice, but the postmortem finding of elongated intracytoplasmic neuronal inclusions (Negri bodies) is diagnostic of rabies. Negri bodies are filled with virus particles and are most often found in the hippocampus and cerebellar cortex.


Usmle neuroscience review

  • A 5-year-old mentally retarded boy is brought to the city from a rural community for evaluation. A careful history reveals mental retardation in a number of other family members, especially the males.

  • Physical examination is remarkable for a long face with large ears, a large jaw and bilateral enlargement of the testes. This presentation is suggestive of

  • A. Down's syndrome

  • B. Edward's syndrome

  • C. Fragile X syndrome

  • D. Klinefelter's syndrome

  • E. Turner's syndrome


The correct answer is c6

The correct answer is C.

  • Enlarged testes are the most specific phenotypic feature to suggest Fragile X syndrome in an individual who appears to have a hereditary mental retardation.

  • The condition has unusual genetics as it is related to expansion of a CGG repeat sequence located on the X chromosome.

  • The larger the number of repeats, the higher the probability of significant retardation, hence the retardation tends to become more severe in successive generations, as more CGG repeats accumulate.

  • Sisters of affected males tend to show milder retardation than their brothers.


Usmle neuroscience review

  • Features of Down's syndrome (choice A), or trisomy 21, include mental retardation, epicanthal folds, dysplastic ears, hypotonia, a horizontal palmar crease (simian crease), redundant neck skin, and a short trunk.

  • Edwards' syndrome (choice B), or trisomy 18, causes death in infancy. Characteristics include rocker bottom feet, low set ears, micrognathia, congenital heart disease, and mental retardation.


Usmle neuroscience review

  • Klinefelter's syndrome (47, XXY; choice D) is associated with testicular atrophy, a eunuchoid body shape, long extremities, and a small penis.

  • Turner's syndrome (45, X; choice E)

  • Female phenotype with short stature, ovarian dysgenesis and webbing of the neck.

  • Coarctation of the Aorta, notching of ribs on CXR

  • High BP in arms , low in legs


Usmle neuroscience review

  • A 13-year-old boy is brought to a rural clinic because of poor school performance. His parents state that he did not begin talking until after three years of age, and still does not use language as effectively as his sister, who is 6-years-old.

  • A careful family history reveals that a maternal grandfather was mildly retarded. The mother has two sisters, both of whom are apparently normal, but the mother admits that she did not do well in school, and dropped out at the age of 16. Physical examination of the child reveals large ears, a long, narrow face, and large testes. Which of the following genetic mechanisms most likely accounts for the observed findings in the son?

  • A. Expanded trinucleotide repeat

  • B. Genomic imprinting

  • C. Robertsonian translocation

  • D. Trisomy 13

  • E. Trisomy 18


The correct answer is a3

The correct answer is A

  • The features described are typical of the familial form of mental retardation known as fragile X syndrome. This disorder is the second most common heritable cause of mental retardation, second only to Down syndrome.

  • Striking features of this disease are that the clinical features tend to worsen with each successive generation, and that males are usually much more severely affected than females, although nearly 50% of carrier females are at least slightly mentally retarded.

  • The explanation appears to involve a region of DNA on the X chromosome that normally contains 6-54 tandem repeats of the sequence CGG. Carrier females for fragile X syndrome may have up to 200 CGG repeats.

  • Clinically affected individuals have 250-4,000 repeats of the CGG sequence. The greater the number of repeats, the more severe the retardation tends to be. Amplification of premutations to full mutations appears much more likely to occur during oogenesis than spermatogenesis.


Usmle neuroscience review

  • Genomic imprinting (choice B) is a phenomenon in which the phenotypic expression of a gene differs if the gene is inherited from the mother, rather than the father.

  • An example of this effect is Angelman ("happy puppet") syndrome, caused by a deletion of band q12 in the maternal copy of chromosome 15.

  • A similar deletion in the paternal chromosome 15 produces a different disease called Prader-Willi syndrome.

  • Prader-WilliPPaternal


Usmle neuroscience review

  • An elderly nursing home patient has had multiple small strokes. On several occasions she has aspirated food, and neurological examination reveals that her gag reflex is absent. These findings suggest involvement of the nucleus of which of the following cranial nerves?

  • A. Facial (VII)

  • B. Glossopharyngeal (IX)

  • C. Hypoglossal (XII)

  • D. Spinal accessory (XI)

  • E. Vestibulocochlear (VIII)


The correct answer is b7

The correct answer is B.

  • Cranial nerve IX is the glossopharyngeal nerve, which has a nucleus in the medulla and is necessary for the gag reflex.

  • Predominantly sensory, except for stylopharyngeus.

  • The gag reflex is elicited by touching either side of the posterior pharynx with a tongue blade, producing bilateral elevation of the palate and bilateral contraction of the pharyngeal muscles.

  • The afferent of this reflex arc consists of the ipsilateral glossopharyngeal nerve, while the vagus nerve, bilaterally, supplies the efferent limb.


Usmle neuroscience review

  • Cranial nerve VII (choice A) is the facial nerve, which supplies motor function to the face, but does not supply the oropharynx.

  • Cranial nerve XII (choice C) is the hypoglossal nerve, which supplies the tongue. It is not involved in the gag reflex.

  • Cranial nerve XI (choice D) is the spinal accessory nerve, which supplies the trapezius and sternocleidomastoid.

  • Cranial nerve VIII (choice E) is the vestibulocochlear nerve, responsible for hearing and equilibrium.


Cranial nerve reflexes

Cranial nerve reflexes

  • GagIX SensoryX Motor

  • CornealV SensoryVII Motor

  • Pupillary LightII SensoryIIIParasympathetic ( via branch to Inf Ob)Present with cortical blindness


Usmle neuroscience review

  • While performing a subtotal thyroidectomy, a surgeon inadvertently sections the recurrent laryngeal nerve.

  • Which of the following muscles would retain its innervation subsequent to this injury?

  • A. Cricothyroid

  • B. Lateral cricoarytenoid

  • C. Posterior cricoarytenoid

  • D. Thyroarytenoid

  • E. Vocalis


The correct answer is a4

The correct answer is A.

  • The recurrent laryngeal nerve is a branch of the vagus nerve, which innervates all of the intrinsic laryngeal muscles except for the cricothyroid muscle.

  • The cricothyroid is attached to the cricoid cartilage and the thyroid cartilage; contraction of this muscle tends to stretch and adduct the vocal ligament.

  • The cricothyroid is innervated by the external laryngeal nerve.


Usmle neuroscience review

  • The lateral cricoarytenoid muscle (choice B) is innervated by the recurrent laryngeal nerve, and is attached to the cricoid cartilage and the arytenoid cartilage. Its contraction causes adduction of the vocal ligament.

  • The posterior cricoarytenoid muscle (choice C) is innervated by the recurrent laryngeal nerve, and is attached to the cricoid cartilage and the arytenoid cartilage. Its contraction causes abduction of the vocal ligament.

  • The thyroarytenoid muscle (choice D) is innervated by the recurrent laryngeal nerve, and is attached to the thyroid cartilage and the arytenoid cartilage. Its contraction causes slackening of the vocal ligament.

  • The vocalis muscle (choice E) is the most medial part of the thyroarytenoid muscle. It attaches to either the thyroid cartilage and the vocal ligament, or the arytenoid cartilage and the vocal ligament. It is innervated by the recurrent laryngeal nerve. Its contraction causes tension on segments of the vocal ligament.


Usmle neuroscience review

  • A 50-year-old woman presents with problems with sleep and headaches.

  • The patient's pupils are 5 mm in size, equal and reactive, with both the direct and consensual light reflexes intact. Accommodation is unimpaired.

  • Examination of the visual fields and fundoscopy are unremarkable. Extraocular movements reveal that she is unable to look upwards. No other abnormalities are found on the neurological examination.

  • Which of the following is the most likely diagnosis?

  • A. Acoustic neuroma

  • B. Astrocytoma in the cerebellum

  • C. Craniopharyngioma

  • D. Parasagittal meningioma

  • E. Pinealoma


The correct answer is e4

The correct answer is E.

  • This patient has a pinealoma.

  • Tumors of the pineal gland compress the vertical gaze center in the tectum of the midbrain.

  • The pineal gland manufactures melatonin from its precursor serotonin; an inadequate supply of melatonin results in insomnia.

  • Tumors of the pineal gland will not compress the cerebral cortex or the rest of the brainstem.

  • Frequently, the only physical sign noted is failure of upward gaze.


Pinealoma

Pinealoma


Usmle neuroscience review

  • An acoustic neuroma (choice A) is a schwannoma of the eighth cranial nerve. It results in deafness, ataxia, and dysarthria. Nystagmus may be present. The gaze centers are not affected.

  • Astrocytomas of the cerebellum (choice B) are usually seen in children. These tumors present with headache, nausea, vomiting, papilledema, and cerebellar signs such as ataxia, dysarthria, nystagmus, and intention tremor. The gaze centers are not affected.

  • Craniopharyngiomas (choice C) are usually seen in children. There is failure of growth, headaches, and bitemporal hemianopia.

  • Parasagittal meningiomas (choice D) usually result in headache, spastic paresis, and urinary incontinence *89


Usmle neuroscience review

  • A 2-year-old girl is evaluated because of deteriorating vision. On physical examination, a whitish hue is noted in the right pupil, along with strabismus.

  • Palpation of the eye elicits apparent pain and tenderness. The patient is referred to an ophthalmologist, who schedules surgery, and removes a multifocal tumor from the right eye. The pathology report notes the presence of rosettes composed of cuboidal-to-columnar cells surrounding a central lumen in the tumor.

  • In all likelihood, this child's condition stems from a mutation in a gene on chromosome

  • A. 5 B. 7

  • C. 9 D. 13 E. 21


The correct answer is d2

The correct answer is D.

  • The description of this case is classic for retinoblastoma, the most common malignant eye tumor of childhood.

  • Retinoblastoma presents as in the question, and microscopically is composed of neuroepithelial cells that form characteristic rosettes (Flexner-Wintersteiner rosettes).

  • Familial retinoblastoma is often bilateral or multifocal, as in this case.


Retinoblastoma

Retinoblastoma


Usmle neuroscience review

  • Retinoblastoma is associated with an abnormality in which chromosome?

  • A. 5

  • B. 8

  • C. 13

  • D. 21

  • E. X


The correct answer is c7

The correct answer is C.

  • About 20% of patients with chromosome 13 abnormality (13q-syndrome) develop retinoblastoma.

  • There is also a genetic dominant form of retinoblastoma that has an 80% penetrance rate.

  • Retinoblastomas that have a genetic basis are more apt to be bilateral than the spontaneous lesions.

  • Retinoblastomas are composed of masses of small hyperchromatic cells that may form small rosettes composed of radially arranged cells surrounding a central lumen.


More detail on retinablastoma

More detail on retinablastoma..

  • A preexisting mutation of a tumor suppressor gene, Rb, located on chromosome 13 (13q14) is present, but causes no symptoms.

  • A second, somatic mutation in a retinal cell leads to loss of a nuclear protein that prevents the retinal cell from exiting G1, allowing development of the tumor.

  • In cases of sporadic retinoblastoma, mutations must occur in both chromosomes 13 of a somatic cell, a rare event, hence sporadic retinoblastoma is always unifocal and unilateral.


Usmle neuroscience review

  • A baby is born with a large defect in the occipital bone through which the posterior portion of the brain has herniated. Which of the following terms best describes this lesion?

  • A. Encephalocele

  • B. Meningocele

  • C. Myelocele

  • D. Spina bifida

  • E. Syringomyelia


The correct answer is a5

The correct answer is A.

  • The central neurons system and its overlying bones are subject to a variety of malformations and developmental diseases.

  • The defect described in the question stem is a cranial encephalocele, in which brain herniates through a defect in the skull bones.

  • The most common site for such a herniation is the occipital bone.

  • Small defects in the occipital bone can be treated surgically, but large defects are very problematic, particularly if significant herniation has occurred, since the brain becomes very vulnerable to trauma and infection.


Usmle neuroscience review

  • Meningocele (choice B) is the term used when the meninges, but not the brain or spinal cord, herniate through a defect in the bony cranium or spinal column.

  • Myelocele (choice C) is the term used when the spinal cord herniates through a defect in the spinal column.

  • Spina bifida (choice D) refers to vertebral defects through which the spinal cord or meninges may herniate.

  • Syringomyelia (choice E) is a tubular, fluid-filled cavity within the spinal cord.


Ntd s

NTD’s


Usmle neuroscience review

  • A patient with long-standing hypertension dies in a car accident.

  • At autopsy, multiple, small, cavitary lesions are observed in the basal ganglia. This finding is most consistent with pathology of which of the following arteries?

  • A. Anterior cerebral

  • B. Lateral striate

  • C. Posterior cerebral

  • D. Superior cerebellar

  • E. Vertebral


The correct answer is b8

The correct answer is B.

  • The lateral striate arteries are penetrating branches of the middle cerebral artery that supply the caudate, putamen, globus pallidus, and internal capsule.

  • Lacunar infarcts, small cavitary lesions that commonly occur in the distribution of the lateral striate and lenticulostriate arteries, are relatively common in the context of long-standing hypertension.

  • The basal ganglia and thalamus are favorite sites for lacunar infarcts.


Usmle neuroscience review

  • The anterior cerebral artery (choice A) supplies the medial surface of the cerebral hemispheres extending from the frontal pole to the parieto-occipital sulcus.

  • It therefore supplies the leg and foot area of the motor and sensory cortices.

  • The posterior cerebral artery (choice C) supplies the occipital lobe, which contains the visual cortex. Occlusion of this vessel results in contralateral hemianopia with macular sparing.

  • This vessel also supplies the inferior surface of the temporal lobe (which contains the hippocampal formation) and the thalamus. It also provides the major blood supply to the midbrain.


Usmle neuroscience review

Posterior circulation – posterior cerebral artery

Calcarine a.

Splenial a.

PCA


Usmle neuroscience review

Middle cerebral artery

Top of circular

sulcus

M3

M4

M2

Sylvian Fissure

A2

HA

M1

M1 (pre-bifurcation)

M1 (post-bifurcation)

M2 segments

Genu

M3 segments

ICA

M4 segments (cortical branches)

M4

  • MCA bifurcates 78%, trifurcates 12%, multiple 10%


Usmle neuroscience review

Middle cerebral artery


Usmle neuroscience review

Middle cerebral artery

  • Perforators- basal ganglia- internal capsule- corona radiata

  • Cortical branches - motor cortex- sensory cortex - speech - vision (temporal loop)


Usmle neuroscience review

Anterior cerebral artery

A2

A1

Frontal lobe

ACA

  • Terminal branch of ICA

  • Passes above optic nerve

  • Linked by communicating artery

  • Enters interhemispheric fissure

MCA

ICA

ON


Usmle neuroscience review

Anterior cerebral artery

CC

CM

PC

A2

Frontal lobe

CM

PC

A2

  • Passes above corpus callosum

  • Courses along medial hemispheric surface


Usmle neuroscience review

Anterior cerebral artery

  • Perforators- optic chiasm, tract- hypothalamus- ant limb internal capsule

  • Branches - corpus callosum- gyrus rectus- motor cortex (leg)- sensory cortex (leg)


Usmle neuroscience review

  • The superior cerebellar artery (choice D) supplies the superior cerebellar peduncle, the superior surface of the cerebellum, and the deep cerebellar nuclei. It also supplies the dorsolateral tegmentum of the rostral pons.

  • The vertebral artery (choice E), a branch of the subclavian artery, gives rise to the posterior inferior cerebellar artery (PICA) and the anterior spinal artery. PICA supplies the dorsolateral quadrant of the medulla and the inferior surface of the cerebellum.

  • The anterior spinal artery supplies the anterior two-thirds of the spinal cord.


Usmle neuroscience review

  • A 28-year-old male with history of mood disorder presents with a decreased need for sleep, irritability, recklessness, and increased energy.

  • Which of the following is the most likely additional presenting symptom?

  • A. Depressed mood

  • B. Fear of dying

  • C. Insomnia

  • D. Racing thoughts

  • E. Recurrent thoughts and actions that relieve anxiety when carried out


The correct answer is d3

The correct answer is D.

  • The presentation suggests a manic or hypomanic episode of a mood disorder. Patients in a manic episode often have an elated or euphoric mood and racing thoughts.

  • Other symptoms of mania include increased energy, hypersexuality, grandiosity, and increased talkativeness.

  • In some patients, irritability, rather than euphoria, is characteristic.


Usmle neuroscience review

  • Depressed mood (choice A) can include anhedonia, decreased self-esteem, energy, concentration, appetite, and libido, as well as increased guilt and sucidality.

  • An unreasonable fear that one might die (choice B) may be associated with panic disorder. Neurovegetative symptoms including severe anxiety, palpitation, shortness of breath, chest pain, trembling, and paresthesias may also occur.

  • Despite poor sleep, manic patients do not complain of insomnia (choice C). Their need for sleep is decreased. During depressive episodes, patients complain of insomnia or hypersomnia.

  • Obsessive-compulsive disorder is characterized by distressing recurrent thoughts (obsession) and actions (compulsion) (choice E) that relieve anxiety when carried out.


Usmle neuroscience review

  • A 65-year-old woman has a long-standing dementing disorder characterized by deterioration in personality, neglect of personal hygiene, impaired judgment, and disinhibited behavior.

  • MRI demonstrates severe cortical atrophy limited to the frontal lobes and anterior two thirds of the temporal lobes, while the remaining cortex is preserved.

  • No evidence of recent or remote infarcts is found.

  • Which of the following diagnoses is most consistent with these pathologic and clinical features?

  • A. Alzheimer disease

  • B. Creutzfeldt-Jacob disease

  • C. Dementia with Lewy bodies

  • D. Pick disease

  • E. Vascular dementia


The correct answer is d4

The correct answer is D

  • Not all dementing disorders manifest with the same clinical features.

  • There are classic presentations that allow identification of a specific form of dementia with a high degree of confidence.

  • In this case, the patient has symptoms due to frontal lobe damage, eg, disinhibition, impaired judgment, and personality changes.

  • Furthermore, MRI demonstrates a specific pattern of cortical atrophy, restricted to the frontal lobes and anterior portion of the temporal lobes.

  • This combination points toward a group of dementias called frontotemporal dementia, the most frequent form of which is Pick disease.

  • Other forms of frontotemporal dementia are very infrequent. Remember: frontal symptoms in conjunction with frontotemporal atrophy = frontotemporal dementia/Pick disease.


Cerebral atrophy demnetia

Cerebral Atrophy - Demnetia


Usmle neuroscience review

  • Alzheimer disease (choice A) is the most frequent form of dementia in industrialized countries. Although symptoms due to frontal damage may be present in Alzheimer disease, they are usually associated with a more generalized impairment of higher neurologic functions, eg, language, memory, and learned movements. In addition, cortical atrophy in Alzheimer disease is widespread and not limited to the frontal and anterior temporal lobes.

  • Creutzfeldt-Jacob disease (choice B) represents the prototype of prion diseases. Cortical atrophy is not a prominent feature of Creutzfeldt-Jacob disease, which manifests with personality changes, memory loss, and seizures, leading to death after a rapid clinical course (a few months to 1 year).


Usmle neuroscience review

  • Dementia with Lewy bodies, also known as diffuse Lewy body disease (choice C), is one of the most common forms of dementia in Western countries.. It is characterized by widespread formation of Lewy bodies in the substantia nigra, limbic cortex, and subcortical nuclei, such as the basal nucleus of Meynert.

  • Extrapyramidal symptoms similar to Parkinson disease manifest in this form of dementia as a result of degeneration of dopaminergic pathways.

  • Vascular dementia (choice E) is an umbrella term encompassing dementing conditions that arise from pathology of large or small cerebral vessels. It manifests with memory loss associated with focal neurologic symptoms depending on the location of damage. MRI would identify old or recent infarcts, as well as white matter disease.


Usmle neuroscience review

Negri bodies, round eosinophilic cytoplasmic inclusions are pathognomonic of rabies (HE, high power).

Hippocampal neurons are the preferential site of Negri body formation.

Picks dementai is one of the frontal lobar dementias, primarily characterized by the presence of distinct argyrophilic (silver staining) spherical inclusions called Pick bodies and globose neurons


Usmle neuroscience review

LBs are filamentous inclusions within neurons. characteristic spherical appearance with a loose radiating array of filaments in the periphery or "corona" surrounding a matted meshwork of filaments in the center or "core".

Neurofibrillary tangles are an intracellular abnormality, involving the cytoplasm of nerve cells. 

They are most readily visualized in sections stained by using silver impregnation techniques


Usmle neuroscience review

  • Absence Seizures (Petit Mal) are characterized by which of the following:A. Post ictal confusionB. Loss of postural controlC. Typical duration of 1 to 2 minutesD. All of the above

  • E. None of the above


Usmle neuroscience review

E

  • Absence seizures involve a abrupt loss & return of consciousness (brief), often without major motor component (eg. eye blinking). It can occur hundreds per day without recognition. Onset usually in young children.


Match the epilepsy type with the treatment idiopathic generalized tonic clonic epilepsy

Match the epilepsy type with the treatment: Idiopathic generalized tonic-clonic epilepsy

  • A. ACTH and/or vigabatrin

  • B. Valproic acid

  • C. Phenytoin or Tegretol or Valproic acid

  • D. Ethosuximide or Valproic acid

  • E. Felbamate or Clonazepam


Usmle neuroscience review

B

  • Generalized epilepsyValproate

  • Focal epilepsyCarbamazepinePhenytoin

  • Absence epilepsyEthosuxamide

  • Lennox-Gastaut synd.Felbamate


Usmle neuroscience review

Match the epilepsy type with the treatment:Juvenile myoclonic epilepsySub-type of generalized epilepsy

  • A. ACTH and/or vigabatrin

  • B. Valproic acid

  • C. Carbamazepine

  • D. Ethosuximide or Valproic acid

  • E. Felbamate or Clonazepam 


Usmle neuroscience review

B

  • Generalized epilepsyValproate

  • Focal epilepsyCarbamazepinePhenytoin

  • Absence epilepsyEthosuxamide

  • Lennox-Gastaut synd.Felbamate


Match the epilepsy type with the treatment childhood absence epilepsy

Match the epilepsy type with the treatment:Childhood absence epilepsy

  • A. ACTH and/or vigabatrin

  • B. Valproic acid

  • C. Phenytoin or Tegretol or Valproic acid

  • D. Ethosuximide or Valproic acid

  • E. Felbamate or Clonazepam


Usmle neuroscience review

D


Usmle neuroscience review

  • A 32-year-old man presents to the emergency room with a severe headache. Nuchal rigidity is found on physical examination. Lumbar puncture demonstrates cerebrospinal fluid with markedly increased lymphocytes. Other cell populations are not increased. Which of the following agents is the most likely cause of his symptoms?

  • A. Escherichia coli

  • B. Haemophilus influenzae

  • C. Herpes virus

  • D. Mycobacterium tuberculosis

  • E.Treponema pallidum   

  • Bonus question :

  • What is the most common cause of bacterial meningitis in this age group ?


The correct answer is c8

The correct answer is C

  • The clinically suspected diagnosis is meningitis, which is confirmed by the abnormal cerebrospinal fluid.

  • The markedly increased lymphocytes suggests acute lymphocytic meningitis, which is distinguished from acute pyogenic meningitis (increased neutrophils as well as lymphocytes).

  • Acute lymphocytic meningitis is usually viral in origin. Among the many viruses that have been implicated, mumps, herpes, Epstein-Barr, echovirus, and Coxsackie virus are the most common.

  • Escherichia coli (choice A) and Haemophilus influenzae (choice B) cause acute pyogenic meningitis.

  • Mycobacterium tuberculosis (choice D) and Treponema pallidum (choice E) cause chronic meningitis

  • Bonus question :

  • What is the most common cause of bacterial meningitis in this age group ?


Mengitis

Mengitis


Usmle neuroscience review

  • Which of the pharyngeal pouches develops into the palatine tonsil?

  • A. First

  • B. Second

  • C. Third

  • D. Fourth

  • E Fifth


The correct answer is b9

The correct answer is B

  • The epithelial lining of the second pharyngeal pouch buds into the mesenchyme to form the palatine tonsil. Part of the pouch remains in the adult as the tonsillar fossa.

  • The first pharyngeal pouch (choice A) develops into the middle ear cavity and eustachian tube.

  • The third pharyngeal pouch (choice C) develops into the thymus and the inferior parathyroid glands.

  • The fourth pharyngeal pouch (choice D) gives rise to the superior parathyroid glands.

  • The fifth pharyngeal pouch (choice E) gives rise to the C cells of the thyroid gland. These cells secrete calcitonin-a hormone that lowers serum calcium.


Usmle neuroscience review

  • 1stmiddle ear cavity and eustachian tube.

  • 2ndPalatine tonsil. Part of the pouch remains in the adult as the tonsillar fossa.

  • 3rdthymus and the inferior parathyroid glands.

  • 4thsuperior parathyroid glands.

  • 5thC cells of the thyroid gland : calcitonin

  • NoteDiGeorge syndrome


Digeorge syndrome dgs

DIGEORGE SYNDROME; DGS

CHROMOSOME 22q11.2 DELETION SYNDROME

“ THIRD AND FOURTH PHARYNGEAL POUCH SYNDROME”

HYPOPLASIA OF THYMUS AND PARATHYROIDS

  • DiGeorge syndrome (DGS) comprises hypocalcemia arising from parathyroid hypoplasia, thymic hypoplasia, and outflow tract defects of the heart. Disturbance of cervical neural crest migration into the derivatives of the pharyngeal arches and pouches can account for the phenotype.


Usmle neuroscience review

Ophthalmoscopic examination of a 5-year-old child demonstrates a retinal angioma. This finding should suggest the possibility of which of the following syndromes?

  • A. Neurofibromatosis type I

  • B. Neurofibromatosis type II

  • C. Sturge-Weber disease

  • D. Tuberous sclerosis

  • E. Von Hippel-Lindau disease 


The correct answer is e5

The correct answer is E.

  • Retinal angioma may be a "visible" manifestation of von Hippel-Lindau disease.

  • This syndrome is characterized by tumors and/or cysts that can involve many structures: retinal angiomas, capillary hemangioblastomas of the CNS (notably cerebellum.

  • Also many other sites), renal carcinoma (up to 30% of cases, may occur at a young age or may be bilateral).

  • Angiomatous or cystic lesions of many other organs (epididymis, kidneys, liver, pancreas, lung, skin).


Usmle neuroscience review

  • Neurofibromatosis type I (choice A) is characterized by Lisch nodules of the iris, café-au-lait macules, and peripheral nerve tumors.

  • Neurofibromatosis type II (choice B) is characterized by acoustic neural tumors and café-au-lait macules.

  • Sturge-Weber disease (choice C) is characterized by port-wine nevus of the head and leptomeningeal angiomatosis.

  • Tuberous sclerosis (choice D) is characterized by adenoma sebaceum of the skin and cortical tubers.


Usmle neuroscience review

NF 1


Usmle neuroscience review

NF 2


Sturge weber

Sturge Weber


Usmle neuroscience review

  • A neurologist gives a car accident victim a neurological examination.As part of the examination, he presents the patient with a picture of a dog and asks her to talk about it. She seems unable to name or recognize the picture.

  • He then asks her to copy a picture of the dog, which she is able to do, although she still is unable to identify the animal as a dog. Which of the following is the most appropriate diagnosis?

  • A. Agnosia

  • B. Alexia

  • C. Aphasia

  • D. Apraxia

  • E. Dyslexia


The correct answer is a6

The correct answer is A

  • Agnosia is the inability to recognize, despite adequate sensation. This patient has a type of agnosia known as visual agnosia, which is the inability to recognize familiar objects despite the ability to see.

  • The fact that she could copy a picture of the dog indicates that she has adequate visual acuity, visual fields, and perception.

  • If this patient had only visual agnosia, if she were to hear a dog bark (auditory) or pet a dog (tactile), then she would be able to recognize and name the dog.

  • Prosopagnosia is a special type of visual agnosia in which a person is unable to recognize faces.

  • There are also other types of agnosias, including auditory and tactile agnosias.


Usmle neuroscience review

  • Alexia (choice B) is an acquired reading disorder due to brain damage. People with this disorder can comprehend words that are spelled out loud, and can understand words and letters that are written on the palm, but they cannot read.

  • Aphasia (choice C) is an acquired disorder of language due to brain damage. Examples are Broca's aphasia and Wernicke's aphasia.

  • Apraxia (choice D) is the loss of the ability to carry out certain movements correctly in response to stimuli that normally elicit them. This occurs even though the patient has no sensory loss, no weakness, and no disturbance of language comprehension.

  • Dyslexia (choice E) is a developmental reading disorder.


Usmle neuroscience review

  • A 24-year-old truck driver presents with a fracture of the midshaft portion of the right humerus. Upon examination, the physician determines that the patient has a wrist drop on the right. The patient can flex all of his fingers but he cannot make a tight fist with his right hand. What nerve was injured as a result of this fracture?

  • A. Axillary nerve

  • B. Long thoracic nerve

  • C. Median nerve

  • D. Musculocutaneous nerve

  • E. Radial nerve


The correct answer is e6

The correct answer is E

  • The radial nerve lies in the musculospiral groove of the humerus, and is subject to injury in association with a fracture of the midshaft of the humerus. The radial nerve innervates the extensor muscles of the forearm, including the muscles that extend the wrist; paralysis of these muscles results in a wrist drop.

  • Although the muscles responsible for flexing the digits are not innervated by the radial nerve, the making of a tight fist requires that the wrist be stabilized with the wrist extensors.

  • The axillary nerve (choice A) leaves the axilla through its posterior wall and is not located in the region of the midshaft of the humerus.

  • The axillary nerve innervates the deltoid and the teres minor muscles, neither of which have any function in the hand.


Usmle neuroscience review

  • The long thoracic nerve (choice B) lies against the chest wall and is not subject to injury as a result of a humeral fracture. The long thoracic nerve innervates the serratus anterior muscle.

  • The median nerve (choice C) passes though the arm, but is not in close contact with the humerus in the midshaft region. The nerve is separated from the bone by the brachialis muscle. The median nerve innervates many muscles of the anterior compartment of the forearm responsible for flexion of the wrist and digits.

  • The musculocutaneous nerve (choice D) is not in contact with the humerus. It innervates the muscles in the anterior compartment of the arm. These muscles have no function in the hand.


Usmle neuroscience review

  • A 52-year-old female complains of sudden visual abnormalities.Her history reveals a 30 pack-year history of smoking, hypertension,and hypercholesterolemia. A head CT shows a lesion in the right occipital lobe and an angiogram reveals an embolic stroke of the right posteriorcerebral artery. What type of visual deficit is she most likely experiencing?

  • A. Bitemporal hemianopia

  • B. Central scotoma

  • C. Left homonymous hemianopia

  • D. Left superior quadrantanopia

  • E. Right homonymous hemianopia

  • F. Right superior quadrantanopia

  • E.Total left eye blindness

  • F.Total right eye blindness.  


The correct answer is c9

The correct answer is C

  • The posterior cerebral arteries supply the cortical surfaces of the occipital and medial temporal lobes.

  • Damage to one occipital lobe (e.g., by trauma or by ischemia/infarction due to stroke) usually produces a contralateral homonymous hemianopia.

  • Occlusion of the right posterior cerebral artery would therefore result in a left homonymous hemianopia-blindness in the left half of the visual field in both eyes.

  • In addition, involvement of the medial temporal lobe might give rise to peduncular hallucinosis-visual illusions or elementary (unformed) hallucinations.

  • Bilateral lesions would cause "cortical" blindness, which does not affect the pupillary reflexes.


Usmle neuroscience review

  • Bitemporal hemianopia (choice A) is a loss of vision in the temporal quadrants of the visual field. (It is also termed heteronymous hemianopia). This occurs in lesions of the optic chiasm, which may occur with pituitary tumors.

  • Central scotoma (choice B) is a loss of vision in the center of the visual field, with preservation of the peripheral fields. It is associated with optic neuritis, a common complication of multiple sclerosis.

  • Superior quadrantanopia (choices D and F) is caused by lesions in the upper portion of the contralateral temporal lobe.

  • Right homonymous hemianopia (choice E) would result from left posterior cerebral artery occlusion.

  • Total blindness in one eye (choices G and H) occurs when its optic nerve is severed.  


Usmle neuroscience review

  • A 19-year-old male is thrown off his motorcycle, sustaining head trauma. He loses consciousness for a moment, then quickly regains consciousness, complaining of a headache. He subsequently vomits and becomes very drowsy. In the ER he is unconscious and has anisocoria, with a dilated right pupil. Hemiplegia and a positive Babinski sign are noted on the left side. A CT scan reveals an epidural hematoma. Within which of the following anatomic spaces is the artery that is bleeding normally found?

  • A. Anterior cranial fossa

  • B. Inferior orbital fissure

  • C. Middle cranial fossa

  • D. Posterior cranial fossa

  • E.       Superior orbital fissure


The correct answer is c10

The correct answer is C.

  • The middle meningeal artery is a branch of the maxillary artery. It enters the intracranial cavity through the foramen spinosum, which is located in the floor of the middle cranial fossa.

  • A tear of the middle meningeal artery results in accumulation of blood between the inner table of the skull and the dura mater.

  • This is called an epidural hematoma. Pressure on the parasympathetic fibers within the oculomotor nerve causes pupillary dilatation.

  • A "blown pupil" is a fully dilated and fixed pupil. The term anisocoria means inequality in the size of the pupils.

  • In this case, the right pupil would be larger than the left.


Usmle neuroscience review

  • The anterior cranial fossa (choice A) receives the central processes of the bipolar neurons that form the olfactory nerve. This enters the intracranial cavity via the cribriform plate of the ethmoid bone.

  • The inferior orbital fissure (choice B) contains veins that communicate with venous plexuses in the pterygopalatine and infratemporal fossae.

  • The posterior cranial fossa (choice D) contains the brainstem and cerebellum.

  • The vertebral arteries enter the posterior cranial fossa through the foramen magnum, where they unite to form the basilar artery.

  • The superior orbital fissure (choice E) contains the ophthalmic vein, and all of the cranial nerves that innervate the eye (CN III, IV, VI) except for the optic nerve (CN II)  


Usmle neuroscience review

  • A neurological examination of a 47-year-old woman reveals a normal corneal reflex in her right eye, but no consensual corneal reflex in her left eye. Which of the following additional findings might be expected?

  • A. Absence of pupillary light reflex of the left eye

  • B. Hyperacusis of the left ear

  • C. Inability to abduct the right eye

  • D. Loss of pain and temperature of the left face

  • E. Loss of taste from the anterior two-thirds of the right tongue

  • F. Ptosis of the left eye


The correct answer is b10

The correct answer is B

  • The corneal reflex is tested by touching a cotton wisp to the eye. A normal response would be blinking of the ipsilateral eye as well as the contralateral eye (consensual reflex).

  • The afferent limb of the corneal reflex is contained within the ophthalmic division of the ipsilateral ophthalmic nerve (V1), the efferent limb is by both (right and left) facial nerves (VII).

  • This woman had a normal corneal reflex in her right eye, indicating a normal right V1 and right VII. However, she lacked a consensual reflex, indicating an abnormal left VIIth nerve.

  • A lesion in the left VIIth would also produce hyperacusis (increased sensitivity to sound) in the left ear because of paralysis of the stapedius muscle, which ordinarily dampens sound transmission through the middle ear.


Usmle neuroscience review

  • The absence of a pupillary light reflex of the left eye (choice A) could be caused either by a lesion of the left optic nerve (CN II; afferent limb) or by a lesion of the left oculomotor nerve (CN III; efferent limb).

  • The inability to abduct the right eye (choice C) could be caused by a lesion of the right abducens nerve (CN VI), which innervates the lateral rectus muscle.

  • Loss of pain and temperature of the left face (choice D) could be caused by a lesion of the spinal nucleus of V. This nucleus is located in the medulla, and receives pain and temperature information from the face via the trigeminal nerve (CN V).

  • Loss of taste from the anterior two-thirds of the right tongue (choice E) could result from a lesion of the right CN VII.

  • Ptosis of the left eye (choice F) could result from a lesion of the left oculomotor nerve (CN III) because of denervation of the levator palpebrae muscle.

  • A lesion of the left VII would result in the inability to close the left eye


Usmle neuroscience review

  • A 50-year-old woman presents with complaints of difficulty rising from a chair or combing her hair. Physical examination is remarkable for erythema and edema of cheeks, eyelids, and the backs of the hands. The lesions have a distinctive mauve color and mauve papules are noted on the knuckles. Approximately 30% of patients with this disorder also may have  

  • A. a mutation in a skeletal muscle protein

  • B. abnormal circulating lymphocytes with cerebriform nuclei

  • C. an underlying malignancy

  • D. bacillary bodies in macrophages in the lamina propria of the intestine

  • E. flattening and blunting of villi in the jejunum    


Usmle neuroscience review

  • This is a typical presentation of dermatomyositis. Approximately 30% of middle aged patients who present with this condition have an underlying malignancy.

  • A wide variety of cancers, particularly adenocarcinomas, can cause dermatomyositis.

  • The mauve papules are known as Gottron's sign, and together with the eyelid involvement, are helpful in distinguishing the rash of dermatomyositis from that of systemic lupus erythematosus.


Usmle neuroscience review

  • Duchenne-type muscular dystrophy is caused by a mutation in a skeletal muscle protein (choice A), dystrophin.

  • Abnormal lymphocytes with cerebriform nuclei (choice B) circulate in Sézary syndrome, which is a leukemic variant of mycosis fungoides, a cutaneous T-cell lymphoma.

  • Bacillary bodies in macrophages within the intestinal lamina propria (choice D) are characteristic of Whipple's disease.

  • Flattening and blunting of villi in the jejunum (choice E) are characteristic of celiac sprue, or gluten-sensitive enteropathy.  


Usmle neuroscience review

  • 6-year-old girl manifests acute vomiting and nuchal rigidity.

  • MRI reveals a tumor in the posterior fossa consisting of a large cyst with a nodular mass attached to its wall (cyst with "mural nodule").

  • Histologic examination shows elongated astrocytes with long bipolar processes and numerous Rosenthal fibers.

  • Which of the following is the most likely diagnosis?

  • A. Astrocytoma, WHO grade II

  • B. Ependymoma

  • C. Glioblastoma multiforme

  • D. Medulloblastoma

  • E. Pilocytic astrocytoma


The correct answer is e7

The correct answer is E

  • Location, gross appearance, and histologic features are typical of pilocytic astrocytoma, an astrocytic tumor with an indolent growth pattern that usually affects children.

  • Cerebellar and hypothalamic regions are the most frequent locations.

  • The presence of Rosenthal fibers is an important histopathologic clue. Rosenthal fibers are corkscrew-shaped, intensely eosinophilic structures deriving from accumulation of ab-crystallin within astrocytic processes.


Usmle neuroscience review

  • Rosenthal fibers are found in pilocytic astrocytoma, reactive gliosis (especially around tumors and vascular malformations), and a rare leukodystrophy known as Alexander disease.

  • Pilocytic astrocytomas have excellent prognosis in the posterior fossa, but complete surgical excision is difficult with tumors in the hypothalamic region. The tumor is classified as a grade I astrocytoma in the WHO system.

  • Remember: a tumor in the cerebellum appearing as a cyst with a mural nodule and containing abundant Rosenthal fibers = Pilocytic astrocytoma. Astrocytoma, grade II (choice A) and glioblastoma


Usmle neuroscience review

  • Astrocytoma, grade II (choice A) and glioblastoma (choice C) are both astrocytomas, ie, tumors of astrocytic origin.

  • Glioblastoma is grade IV according to the WHO system. As their grades suggest, grade II astrocytoma is less anaplastic (ie, less malignant) than grade IV astrocytoma. T

  • hese tumors grow in a diffuse manner, do not possess a cystic component, and usually arise in the white matter of the centrum semiovale.

  • Ependymoma (choice B) originates from the ependyma and develops near the ventricular walls (4th ventricle in children). Ependymomas of the 4th ventricle fill the ventricular cavity but can be easily differentiated from pilocytic astrocytomas in their histologic appearance: ependymal cells organized around small vessels (perivascular pseudorosettes) or around small lumina (true ependymal rosettes), mimicking the primordial ependymal canal.


Usmle neuroscience review

  • Medulloblastoma (choice D) refers to a malignant neoplasm of childhood that presumably originates from immature glioneuronal precursors.

  • It is located in the midline posterior fossa and infiltrates the cerebellar vermis. This tumor is solid (not cystic) and consists of undifferentiated small cells arranged in patternless sheets.


Usmle neuroscience review

  • Neither the anterior interosseus (choice A) nor the musculocutaneous (choice C) nerves supplies the hand.

  • The anterior interosseous nerve supplies the flexor pollicis longus, the lateral half of flexor digitorum profundus, and pronator quadratus.

  • The musculocutaneous nerve supplies the coracobrachialis, biceps, and most of the brachialis muscle, then becomes the lateral cutaneous nerve of the forearm.

  • The radial nerve (choice D) supplies skin on the radial side of the dorsal surface of the hand, but not the fingertips.

  • The ulnar nerve (choice E) supplies the palmar and dorsal surfaces of the medial hand, including the palmar and dorsal surfaces of the fourth and fifth digits.


Usmle neuroscience review

  • A 35-year-old man returns to the U.S. after a recent trip to Central America.

  • A few days later, he develops altered consciousness and extreme irritability.

  • All diagnostic investigations and supportive therapy are unsuccessful, and the patient becomes comatose and dies.

  • Autopsy reveals elongated eosinophilic intracytoplasmic inclusions within the pyramidal neurons of the hippocampus and Purkinje neurons of cerebellum.

  • Which of the following is the most likely diagnosis?

  • A. CMV encephalitis

  • B. Herpes encephalitis

  • C. HIV encephalitis

  • D. Lewy body disease

  • E. Rabies encephalitis


Usmle neuroscience review

  • CMV encephalitis (choice A) affects fetuses (in utero infection) and immunocompromised patients. The most distinctive microscopic feature is the presence of cytomegalic cells, ie, abnormally large cells with a large intranuclear purple inclusion and granular basophilic inclusion in the cytoplasm.

  • Herpes encephalitis (choice B) could be confused with rabies within the clinical context provided here, but it is not associated with Negri bodies. It is caused by Herpes simplex virus type 1 and frequently leads to hemorrhagic necrosis of the temporal lobes.


Usmle neuroscience review

  • HIV encephalitis (choice C) is frequently seen in AIDS patients and is due to direct involvement of the CNS by HIV. Dementia, incontinence, and seizures are frequent manifestations. Pathologic features in the brain include "microglial nodules," which are collections of lymphocytes, histiocytes, and microglial cells with variable numbers of multinucleated giant cells. While microglial nodules are often encountered in viral encephalitides, multinucleated giant cells are characteristic of HIV encephalitis.

  • Lewy body disease (choice D) is a dementing disorder characterized clinically by progressive loss of memory, parkinsonism, and visual/auditory hallucinations, and pathologically by Lewy bodies (round intracytoplasmic neuronal inclusions that contain alpha-synuclein) in the substantia nigra and neocortex. The clinical features are obviously different from rabies. Lewy bodies are also characteristic of Parkinson disease.


Usmle neuroscience review

  • Ultrasound examination of a developing fetus demonstrates a fluid-filled sac at the base of the fetus' spine that connects to the spinal canal and apparently contains part of the spinal cord.

  • A dietary deficiency of which of the following is most strongly associated with this type of lesion?

  • A. Calcium

  • B. Folate

  • C. Iron

  • D. Vitamin C

  • E. Vitamin K


The correct answer is b11

The correct answer is B.

  • The lesion is a neural tube defect, probably a meningomyelocele, in which both meninges and spinal cord herniate through a bony vertebral defect.

  • These defects most commonly occur in the lumbosacral region, typically resulting in motor and sensory deficits in the lower extremities, and bowel and bladder dysfunction.

  • This condition is now known to be associated with low maternal folate during the first three to four weeks of pregnancy, a time when many women may be unaware of their pregnancy.

  • It is now recommended that all women of childbearing age consume at least 400 mg of folic acid daily.

  • Calcium deficiency (choice A) can cause osteoporosis and osteopenia.

  • Iron deficiency (choice C) can cause iron deficiency anemia.

  • Vitamin C deficiency (choice D) can cause scurvy.

  • Vitamin K deficiency (choice E) can cause a bleeding diathesis.


Usmle neuroscience review

  • A 35-year-old patient is given a battery of neuropsychological tests.

  • He scores 85 on the Wechsler Adult Intelligence Scale (WAIS) Verbal IQ, 135 on the Performance IQ test, and 125 on the Wechsler Memory Scale test.

  • Which of the following is the most likely site of his brain dysfunction?

  • A. Bilateral frontal lobes

  • B. Bilateral hippocampal gyri

  • C. Bilateral occipital lobes

  • D. Left hemisphere

  • E. Right hemisphere


The correct answer is d5

The correct answer is D.

  • The pattern presented suggests this person is having difficulties with verbal material (WAIS verbal IQ of 85) but not with visual-spatial tasks (performance IQ) or memory (Wechsler memory scale).

  • Since the left hemisphere is dominant for speech and verbal material in the majority of individuals, the lesion is most likely in the left hemisphere.


Usmle neuroscience review

  • Choice A is incorrect since the frontal lobes control socially appropriate behavior, sequencing, and future planning. There is no indication that these are deficient in this person.

  • Since memory is intact, a lesion in the bilateral hippocampal gyri (choice B) is unlikely.

  • Bilateral occipital lesions (choice C) would produce problems with visual recognition, which are not apparent in this person.

  • The right hemisphere (choice E) is related to control of visual-spatial functions (e.g., map reading, locating oneself in space, etc.), rather than verbal ability.


Usmle neuroscience review

  • CT scan of the head in a patient who had been in an automobile accident fails to demonstrate a pituitary gland.

  • Endocrine evaluation demonstrates serum hormones are all within normal limits. Which of the following is the most likely diagnosis?

  • A. Craniopharyngioma

  • B. Empty sella syndrome

  • C. Hypothalamic suprasellar tumor

  • D. Large pituitary adenoma

  • E. Pituitary microadenoma


The correct answer is b12

The correct answer is B.

  • Empty sella syndrome is an uncommon but dramatic condition in which the pituitary radiologically appears to be completely missing from the sella turcica, which is instead filled with cerebrospinal fluid (CSF).

  • The most common cause is herniation of the arachnoid through the diaphragm sella. This leads to excess local CSF production, in turn causing pressure atrophy of the pituitary.

  • Other causes include Sheehan's syndrome, infarction of an adenoma followed by scarring of the remaining pituitary, and surgery or radiation therapy.

  • Most patients with empty sella syndrome have sufficient residual pituitary parenchyma to prevent hypopituitarism.


Usmle neuroscience review

  • Craniopharyngiomas (choice A) can produce a mass that involves the pituitary.

  • Hypothalamic suprasellar tumors (choice C), including craniopharyngiomas, can produce a mass that involves the pituitary.

  • Large pituitary adenomas (choice D) usually produce a mass lesion. They can infarct and produce empty sella syndrome, but this is rare.

  • Pituitary microadenoma (choice E) would produce no visible radiographic changes.


Usmle neuroscience review

  • A one-year-old baby presents with increasing flaccid paralysis, lack of coordination, and hyporeflexia.

  • Over the next several years, the child's condition deteriorates to a bedridden vegetative state.

  • Funduscopic examination reveals optic atrophy. Extensive enzymological studies document a deficiency of arylsulfatase A (cerebroside sulfatase) in leukocytes.

  • Which of the following is the most likely diagnosis?

  • A. Gaucher's disease

  • B. Krabbe's disease

  • C. Metachromatic leukodystrophy

  • D. Niemann-Pick disease

  • E. Tay-Sachs disease


The correct answer is c11

The correct answer is C.

  • There are a number of hereditary sphingolipidoses that have devastating clinical courses. In practice, these diseases may have a variable course and may be difficult to specifically diagnose reliably on clinical grounds alone.

  • The most useful clue to the specific diagnosis in this case is the comment about the deficient arylsulfatase A.

  • Deficiency of this enzyme produces metachromatic leukodystrophy, characterized by accumulation of cerebroside sulfates (galactosyl sulfatide).

  • The cerebroside sulfates accumulate as intra- and extracellular spherical masses that stain metachromatically (purplish rather than bluish) with acid cresyl violet, particularly in the nervous system.

  • The biochemical diagnosis can be made by evaluating cultured cells from a variety of sources, including leukocytes, fibroblasts, and hair bulbs.

  • The most common presentation is that described in the question stem; adolescent and adult variants also occur.


Usmle neuroscience review

  • Gaucher's disease (choice A) is a sphingolipidosis caused by deficient beta-glucocerebrosidase.

  • Krabbe's disease (choice B) is a sphingolipidosis caused by deficient beta-galactocerebrosidase.

  • Niemann-Pick disease (choice D) is a sphingolipidosis caused by deficient sphingomyelinase.

  • Tay-Sachs disease (choice E) is a sphingolipidosis caused by deficient hexosaminidase A (alpha subunit).


Usmle neuroscience review

  • Which of the following chemotherapeutic agents is specific for the M phase of the cell cycle?

  • A. Cytarabine

  • B. Daunorubicin

  • C. Hydroxyurea

  • D. Mechlorethamine

  • E. Vincristine


The correct answer is e8

The correct answer is E

  • Vincristine (and vinblastine) are Vinca alkaloids that bind to tubulin, a component of cellular microtubules. This leads to disruption of the mitotic spindle apparatus and results in metaphase arrest since the chromosomes are unable to segregate. Since these drugs interfere with mitosis, they are considered cell-cycle specific for the M phase.


Usmle neuroscience review

  • Cytarabine (choice A) belongs to the class of antineoplastics that are antimetabolites. This drug class interferes with normal metabolic pathways by competing for enzymatic sites. Specifically, cytarabine (Ara-C) is a pyrimidine nucleoside analog. It interrupts DNA synthesis and function by inhibiting DNA polymerase and incorporating into the DNA or RNA of the cell. As you would expect, this drug is cell-cycle specific for the S phase.

  • Daunorubicin (choice B) is one of the antibiotic antineoplastic agents (others include dactinomycin, doxorubicin, bleomycin, plicamycin, and mitomycin). These agents work by disrupting DNA functioning. Daunorubicin binds to DNA between base pairs on adjacent strands, resulting in uncoiling of the helix and destruction of the DNA template. While this drug has its maximum effect during the S phase, it is not cell-cycle specific. (Note: the only antibiotic that is cell-cycle specific is bleomycin.)


Usmle neuroscience review

  • Hydroxyurea (choice C) works by interfering with ribonucleoside diphosphate reductase, the enzyme responsible for generating the deoxyribonucleotides needed for DNA synthesis. It is S-phase specific.

  • Mechlorethamine (choice D) is a nitrogen mustard. The nitrogen mustards (mechlorethamine, cyclophosphamide, melphalan, chlorambucil) belong to the larger class of alkylating agents. These agents work by alkylating DNA (along with RNA and proteins). The alkylating agents are generally NOT cell-cycle specific.


Usmle neuroscience review

  • A 47-year-old man with a history of type 2 diabetes, depression, and hypertension presents to the emergency department with spontaneous priapism.

  • Which of the following drugs is the most likely cause of his current condition?

  • A. Atenolol

  • B. Furosemide

  • C. Glyburide

  • D. Paroxetine

  • E. Trazodone


The correct answer is e9

The correct answer is E

  • Priapism is characterized by the development of a painful erection for an extended period of time. When untreated, priapism can cause severe penile damage that can culminate in impotence.

  • Administration of the antidepressant drug trazodone has been associated with priapism in a number of patients.

  • In patients with prolonged or inappropriate penile erection, this medication should be discontinued and medical attention should be sought immediately. Injection of alpha-adrenergic stimulants, such as norepinephrine or epinephrine, may be successful in treating the priapism. Surgical intervention is necessary for the treatment of trazodone-induced priapism in many instances.


Usmle neuroscience review

  • Atenolol (choice A) is a beta-1 adrenergic antagonist indicated for the treatment of hypertension. This agent is commonly associated with impotence in males.

  • Furosemide (choice B) is a loop diuretic indicated for the treatment of edema and hypertension; electrolyte abnormalities are the most common side effects seen with this agent.

  • The sulfonylurea glyburide (choice C) is an oral hypoglycemic agent indicated for the treatment of type 2 diabetes; hypoglycemia is the most common side effect of this agent.

  • Paroxetine (choice D) is a selective serotonin reuptake inhibitor (SSRI) used for the treatment of depression. This agent is commonly associated with impotence in males.


Usmle neuroscience review

  • A 44-year-old male with a history of polysubstance abuse presents with nausea, vomiting, increased heart rate, high blood pressure, sweating, agitation, and weakness. He also complains of seeing monsters on the wall during the interview.

  • Which of the following best accounts for this presentation?

  • A. Alcohol intoxication

  • B. Alcohol intoxication or cocaine withdrawal

  • C. Alcohol withdrawal

  • D. Alcohol withdrawal or cocaine intoxication

  • E. Cocaine intoxication

  • F. Cocaine withdraw


The correct answer is d6

The correct answer is D

  • This man's presentation can be explained either by alcohol withdrawal or by cocaine intoxication.

  • Nausea, vomiting, sympathetic nervous system activation, and weakness could be produced in either case.

  • Visual hallucinations (seeing monsters) can also be accompanied by tactile and auditory hallucinations.

  • In severe cases, either alcohol withdrawal or cocaine intoxication can cause convulsions.


Usmle neuroscience review

  • Alcohol intoxication (choice A and B) is characterized by disinhibition, aggression, impaired attention and judgment, unsteady gait and imbalance, slurred speech, nystagmus, and a decreased level of consciousness.

  • Other symptoms associated with alcohol withdrawal (choices C and D) include insomnia, headache, and tremors of the tongue, eyelids, and outstretched hands.

  • Withdrawal from cocaine (choices B and F) is characterized by dysphoria, lethargy, psychomotor retardation or agitation, increased appetite, sleep disturbances, and bizarre or unpleasant dreams.

  • Other symptoms associated with cocaine intoxication (choices D and E) include grandiosity, paranoid ideation, and pupillary dilatation. Orientation usually remains intact.


Usmle neuroscience review

  • A 17-year-old girl loses her best friend in an automobile accident. After the death, she starts writing for hours daily in her diary.

  • This would most likely be an example of which of the following defense mechanisms?

  • A. Identification

  • B. Projection

  • C. Rationalization

  • D. Regression

  • E. Sublimation


The correct answer is e10

The correct answer is E

  • Sublimation is the diversion of unacceptable impulses into more acceptable ones.

  • In this case, the girl would like to continue to talk to her best friend, but since that is not possible, she substitutes writing in her diary.

  • An example of sublimation seen fairly frequently in medical settings is the mother whose child died of a disease who becomes active in a state or national organization designed to help families with the disease


Usmle neuroscience review

  • Identification (choice A) is the adoption of characteristics or activities of another person.

  • Projection (choice B) occurs when someone attributes their own thoughts to a different person.

  • Rationalization (choice C) is the offering of a false, but acceptable, explanation for behavior.

  • Regression (choice D) is the adoption of behavior more appropriate to a younger age.


Usmle neuroscience review

  • 24-year-old migrant farm worker is rushed to a nearby emergency room after an accidental exposure to parathion.

  • He is in respiratory distress and is bradycardic.

  • Which of the following drugs can be given to increase the activity of his acetylcholinesterase?

  • A. Atropine

  • B. Deferoxamine

  • C. Dimercaprol

  • D. N-acetylcysteine

  • E. Physostigmine

  • F. Pralidoxime


The correct answer is f1

The correct answer is F

  • Pralidoxime (2-PAM) is an acetylcholinesterase (AChE) reactivating agent.

  • It is only useful for counteracting AChE inhibitors which act by phosphorylating the enzyme (organophosphates).

  • Pralidoxime can remove the phosphate group from AChE, thus regenerating the enzyme.

  • This must be done in a timely fashion because normally after the phosphate group is bound to the enzyme, it undergoes a chemical reaction known as "aging."

  • Once this bond ages, pralidoxime will no longer be effective..


Usmle neuroscience review

  • Atropine (choice A) is a nonselective muscarinic antagonist. Although atropine would be an appropriate agent for this patient, it acts by preventing the excess ACh from stimulating muscarinic receptors rather than altering the activity of AChE.

  • Deferoxamine (choice B) is a chelator used for iron poisoning.

  • Dimercaprol (choice C) is a chelator used alone for arsenic, mercury and gold poisoning, and also in conjunction with edetate calcium disodium (EDTA) for the treatment of severe lead poisoning.

  • N-acetylcysteine (choice D) is used to treat acetaminophen overdose.

  • Physostigmine (choice E) is a carbamylating acetylcholinesterase inhibitor that can be used to treat antimuscarinic overdose. This drug would certainly exacerbate this patient's symptoms


Usmle neuroscience review

  • 74-year-old woman with multiple myeloma is being treated with high doses of doxorubicin (Adriamycin).

  • She has also received cyclophosphamide and prednisone recently.

  • During his examination, the physician should check the patient for

  • A. abdominal tenderness

  • B. bladder distention

  • C. limitation of movement

  • D. papilledema

  • E. pulmonary rales


The correct answer is e11

The correct answer is E.

  • Doxorubicin (Adriamycin) is an anthracycline antibiotic which, when given in high doses (> 550mg/m2), can produce cardiomyopathy leading to congestive heart failure, accompanied by pulmonary edema and rales.

  • This complication is especially likely if the patient is over 70 years of age, has received cardiac irradiation, has underlying heart disease or hypertension, or has received cyclophosphamide.

  • Abdominal tenderness (choice A), bladder distention (choice B), limitation of movement (choice C), or papilledema (choice D) are not typically associated with administration of doxorubicin. Doxorubicin does, however, cause alopecia and suppresses the bone marrow. 39 T


Usmle neuroscience review

  • A 27-year-old swimmer who feels insecure about her athletic abilities harshly criticizes her teammates' techniques.

  • Which of the following ego defense mechanisms is she displaying?

  • A. Displacement

  • B. Projection

  • C. Reaction formation

  • D. Repression

  • E. Sublimation


The correct answer is b13

The correct answer is B

  • Projection involves attributing one's own traits, feelings, and attitudes to someone else.

  • This 27-year-old swimmer's harsh criticism of her teammates' abilities is a reflection of her personal feeling of incompetence.

  • (Doubts about her own ability are translated into doubts about her teammates' aptitude.)


Usmle neuroscience review

  • Displacement (choice A) involves the automatic transferring of a wish or an affect from one object to a substitute. For example, a man who is angry at his wife releases his hostility by kicking the table.

  • Reaction formation (choice C) involves turning a repressed impulse or unconscious wish to its opposite. For example, a man who is attracted to his brother's wife develops an aversion to her personality.

  • Repression (choice D) occurs when the conflicting thought or feeling is automatically hidden from the person's awareness. Forgetting an emotionally charged event is an example of repression.

  • Sublimation (choice E) is a very mature mechanism that involves consciously turning socially unacceptable impulses into acceptable or more benign forms. For example, a young college girl immerses herself in athletics rather than engage in premarital sex.


Usmle neuroscience review

  • Rupture of a berry aneurysm (choice D) usually causes a subarachnoid hemorrhage, in which blood leaks into the space between the arachnoid membrane and the brain. The blood may also gain access to the ventricles, but does not generally damage the cerebral hemispheres. Subarachnoid hemorrhages can be sudden and deadly, but usually present with a severe headache ("the worst headache of my life"). These aneurysms are not especially associated with Alzheimer's disease.

  • Rupture of a Charcot-Bouchard aneurysm (choice E) might cause a sudden hemorrhage within the brain causing coma and death, but it is not especially associated with Alzheimer's disease. Charcot-Bouchard aneurysms are primarily seen in patients with severe hypertension.


Usmle neuroscience review

  • 23-year-old man living in a group home for the developmentally challenged has an IQ of 73.

  • He does not read or write, and communicates with one or two word utterances. He will not interact with other group home members, and since birth he has "pulled back" when others get physically close to him.

  • In his room, everything is in a given place; if any of his belongings are moved, he becomes disturbed.

  • Which of the following is the most likely diagnosis?

  • A. Asperger's disorder

  • B. Autistic disorder

  • C. Childhood disintegrative disorder

  • D. Obsessive compulsive disorder

  • E. Schizophrenia, catatonic


The correct answer is b14

The correct answer is B

  • The man is displaying the classic signs of autism, which include withdrawal from interaction with others, failure to use speech for communication, and the obsessive need for sameness.

  • Even though patients with Asperger's disorder (choice A) display a social interaction deficit, there is no language delay. Also, stereotyped patterns of behavior (e.g., hand twisting) occur in this disorder.


Usmle neuroscience review

  • Children with childhood disintegrative disorder (choice C) develop normally for the first two years of life, and then demonstrate deterioration, but this patient has demonstrated pathology from birth.

  • Obsessive compulsive disorder (choice D) does not include withdrawal from physical contact, language impairment, or presence from birth.

  • Schizophrenic disorder, catatonic type (choice E), has its onset in late adolescence, and is characterized by difficulties in movement, and either immobility or excitement. The patients also are negativistic and demonstrate bizarre posturing


Usmle neuroscience review

  • A child psychiatrist would like to evaluate the intellectual ability of a 3-year-old patient. Which of the following is the most appropriate test for him to use?

  • A. Denver Developmental Scale

  • B. Stanford-Binet Scale

  • C. WAIS-R

  • D. WISC III

  • E. WPPSI


The correct answer is b15

The correct answer is B.

  • The Stanford-Binet scale is best for younger children (2-4 years old), since it does not rely exclusively on language.

  • The Denver Developmental Scale (choice A) is used to assess the attainment of developmental milestones in children under 2.

  • The WAIS-R (Wechsler Adult Intelligence Scale; choice C) is used for individuals aged 17 and over. (Just think, the WAIS-R is rated "R").

  • The WISC III (Wechsler Intelligence Scale for Children; choice D) is useful for evaluating children aged 6-16.

  • The WPPSI (Wechsler Preschool and Primary Scale of Intelligence; is used for children aged 4-6.


Usmle neuroscience review

  • A young adult has progressive intellectual deterioration, weakness, ataxia, and seizures. Reference laboratory tests demonstrate an abnormality of an important mitochondrial enzyme. From which of the following diseases is this person most likely suffering?

  • A. Adrenoleukodystrophy

  • B. Central pontine myelinolysis

  • C. Krabbe's disease

  • D. Leigh's disease

  • E. Metachromatic leukodystrophy


The correct answer is d7

The correct answer is D

  • Leigh's disease, also known as subacute necrotizing encephalomyelopathy, is a very rare disease that most physicians will never encounter in real life.

  • The specific defective enzyme, in at least some cases, is cytochrome oxidase, one of the components of the electron transport system.

  • Muscle and brain are particularly affected. Patients have the presentation described in the question and typically die within several years.

  • See next slide for differential


Differential

Differential

  • Adrenoleukodystrophy (choice A) is an X-linked disease with abnormal lipid metabolism leading to demyelination in the CNS.

  • Central pontine myelinolysis (choice B) is characterized by demyelination of the pons (especially the basis pontis) seen after overlying rapid correction of hyponatremia.

  • Krabbe's disease (choice C) is an autosomal recessive accumulation of cerebrosides in histiocytes in the CNS.

  • Metachromatic leukodystrophy (choice E) is an autosomal recessive accumulation of sphingolipids in the CNS and elsewhere.


Usmle neuroscience review

  • A 4-month-old male presents with twitching of the facial muscles. He has previously been seen for several severe episodes of Candida infections. On examination, the child has low-set ears, hypertelorism, and a shortened philtrum. What additional findings would be likely in this individual?

  • A. Absent thymic shadow on chest x-ray

  • B. Decreased alpha-fetoprotein

  • C. Decreased IgA levels

  • D. Elevated IgM levels

  • E. Prominent telangiectasias around the eyes


The correct answer is a7

The correct answer is A

The clinical findings describe DiGeorge syndrome.

Patients clinically present with tetany (usually first noted in the facial muscles) due to hypocalcemia secondary to hypoparathyroidism.

The thymus is absent, as are the parathyroid glands, due to failure of development of the 3rd and 4th pharyngeal pouches.

Recurrent infections due to defective cellular immunity and abnormal facies are additional features.


Usmle neuroscience review

  • Decreased alpha-fetoprotein (choice B) is an amniotic fluid marker for Down's syndrome. Down's syndrome patients have abnormal immune responses that predispose them to serious infections (particularly of the lungs) and to thyroid autoimmune disease. However, there is no defect of the parathyroid glands.

  • Decreased IgA levels (choice C) describes selective IgA deficiency, which is the most common hereditary immunodeficiency. The syndrome is due to a failure of heavy-chain gene switching in B cells.


Usmle neuroscience review

  • Elevated IgM (choice D) is seen in hyper-IgM syndrome. Patients have a high concentration of IgM and normal numbers of T and B cells, but low levels of IgG, IgA, and IgE. Helper T cells have a defect in the surface protein CD40 ligand that interacts with CD40 on the B-cell surface. This results in an inability of the B cell to switch from the production of IgM to other classes of antibodies.

  • Prominent telangiectasias around the eyes (choice E) are seen as part of the ataxia-telangiectasia syndrome. This is an autosomal recessive disorder, and is also referred to as a chromosomal breakage syndrome.

  • Ataxia-telangiectasia is associated with increased numbers of translocations, especially involving the T-cell receptor loci; the gene for this disorder has been mapped to chromosome 11. Patients have an increased incidence of malignancy.


Usmle neuroscience review

  • A 55-year-old male begins group therapy. After the first session, he befriends one of the other clients, and begins telling her how extraordinarily intelligent and talented the facilitator is. At the next session, he and the facilitator disagree. After the session, he tells his fellow group member that the facilitator is utterly incompetent and that they should sue for malpractice. This is an example of

  • A. displacement

  • B. fixation

  • C. reaction formation

  • D. regression

  • E. splitting


The correct answer is e12

The correct answer is E

  • Splitting is a primitive defense mechanism in which objects or people are thought of as either "all bad" or "all good."

  • This defense mechanism is normal in young children, but also occurs in adults with borderline personality disorder (the man in group therapy) or psychosis.


Usmle neuroscience review

  • Displacement (choice A) is an unconscious defense mechanism in which one's feelings or desires are unconsciously transferred from their original object to a more acceptable substitute.

  • Fixation (choice B) refers to an arrest of development at a particular developmental stage. It is generally a partial or incomplete arrest of development, but can contribute to the development of emotional problems if protracted.


Usmle neuroscience review

  • Reaction formation (choice C) refers to an unconscious defense mechanism in which the person takes on an attitude or belief that is the opposite of his or her true beliefs and desires.

  • Regression (choice D) is a return to an earlier (often infantile) stage of development that occurs in many mental illnesses and in normal individuals experiencing tragic or extremely stressful events


Usmle neuroscience review

  • A 20-year-old woman sees her baby cousin for the first time. As she attempts to play with the infant, he begins to cry incessantly. How old is this baby likely to be?

  • A. 1-4 months

  • B. 5-8 months

  • C. 9-12 months

  • D. 13-16 months

  • E. 17-20 months


The correct answer is b16

The correct answer is B

  • The baby is exhibiting stranger anxiety, which normally occurs between the ages of 5 and 9 months.

  • Spontaneous smiling begins within several days after birth and disappears by 3 months.

  • Smiling at any face occurs by 2 months, followed quickly by smiling only at familiar faces and when pleased.

  • By 3 months, infants can imitate facial expressions.

  • They laugh at 4 months.


Continued

Continued……..

  • Separation anxiety occurs between the ages of 10 and 18 months, when the infant is separated from the mother. Between the ages of 2 months and 2 years, children might show preference for a comforting "transitional object" (e.g., teddy bear), which is usually discarded by age 4, when the transition from dependence on the mother to independence is more complete.


Usmle neuroscience review

  • A 24-year-old summer camp counselor complains of a severe headache and weakness. His condition rapidly deteriorates over a period of hours, and he is airlifted to a nearby hospital. A lumbar puncture is performed and a Gram's stain of spinal fluid reveals gram-negative diplococci. Infection with this organism is also associated with which of the following?

  • A. Dysentery

  • B. Erythema chronicum migrans

  • C. Myocarditis

  • D. Ophthalmia neonatorum

  • E. Waterhouse-Friderichsen syndrome


Answer

Answer

E


Usmle neuroscience review

  • In which of the following sites do myxopapillary ependymomas most frequently occur?

  • A. Cerebellum

  • B. Conus medullaris

  • C. 4th ventricle

  • D. Lateral ventricles

  • E. Midbrain


The correct answer is b17

The correct answer is B

  • Myxopapillary ependymoma is a variant of ependymoma, a tumor arising from ependymal cells.

  • Histologically, myxopapillary ependymoma contains a myxoid (mucus-rich) intercellular matrix, in which spindly neoplastic ependymal cells are arranged in a fascicular and papillary pattern (hence its designation).

  • It is a benign tumor that almost always occurs in the distal segment of the spinal cord, ie, the conus medullaris.

  • Once excised, the patient is cured.


Usmle neuroscience review

  • The cerebellum (choice A) is the favorite site for pilocytic astrocytomas, medulloblastomas, and hemangioblastomas, but not ependymomas.

  • In general, classic ependymomas occur in close proximity to the ventricular cavities, specifically, the 4th ventricle (choice C) in children and the lateral ventricles (choice D) in adults.

  • The myxopapillary variant does not occur in either location.

  • A midbrain location (choice E) would be truly exceptional for any type of ependymoma.


Usmle neuroscience review

  • A sharp instrument passing through the superior orbital fissure would most likely sever the

  • A. abducens nerve

  • B. facial nerve

  • C. mandibular nerve

  • D. maxillary nerve

  • E. middle meningeal artery

  • F. ophthalmic artery

  • G. optic nerve


The correct answer is a8

The correct answer is A.

  • A good way to remember what goes through the superior orbital fissure is that everything that innervates the eye, other than the optic nerve, passes through this fissure.

  • This includes the oculomotor nerve (CN III), the trochlear nerve (CN IV), the ophthalmic nerve (V1), and the abducens nerve (CN VI).


Usmle neuroscience review

  • The facial nerve (CN VII; choice B) passes through the internal auditory meatus.

  • The mandibular nerve (V3; choice C) passes through the foramen ovale.

  • The maxillary nerve (V2; choice D) passes through the foramen rotundum.

  • The middle meningeal artery (choice E) passes through the foramen spinosum.

  • The ophthalmic artery (choice F) passes through the optic canal.

  • The optic nerve (choice G) passes through the optic canal.


Usmle neuroscience review

  • An elderly nursing home patient has had multiple small strokes. On several occasions she has aspirated food, and neurological examination reveals that her gag reflex is absent. These findings suggest involvement of the nucleus of which of the following cranial nerves?

  • A. Facial (VII) B.

  • Glossopharyngeal (IX)

  • C. Hypoglossal (XII)

  • D. Spinal accessory (XI)

  • E. Vestibulocochlear (VIII)


The correct answer is b18

The correct answer is B.

  • Cranial nerve IX is the glossopharyngeal nerve, which has a nucleus in the medulla and is necessary for the gag reflex. The gag reflex is elicited by touching either side of the posterior pharynx with a tongue blade, producing bilateral elevation of the palate and bilateral contraction of the pharyngeal muscles.

  • The afferent of this reflex arc consists of the ipsilateral glossopharyngeal nerve, while the vagus nerve, bilaterally, supplies the efferent limb.


Usmle neuroscience review

  • Cranial nerve VII (choice A) is the facial nerve, which supplies motor function to the face, but does not supply the oropharynx.

  • Cranial nerve XII (choice C) is the hypoglossal nerve, which supplies the tongue. It is not involved in the gag reflex.

  • Cranial nerve XI (choice D) is the spinal accessory nerve, which supplies the trapezius and sternocleidomastoid.

  • Cranial nerve VIII (choice E) is the vestibulocochlear nerve, responsible for hearing and equilibrium.


Usmle neuroscience review

  • While performing a subtotal thyroidectomy, a surgeon inadvertently sections the recurrent laryngeal nerve.

  • Which of the following muscles would retain its innervation subsequent to this injury?

  • A. Cricothyroid

  • B. Lateral cricoarytenoid

  • C. Posterior cricoarytenoid

  • D. Thyroarytenoid

  • E. Vocalis


The correct answer is a9

The correct answer is A.

  • The recurrent laryngeal nerve is a branch of the vagus nerve, which innervates all of the intrinsic laryngeal muscles except for the cricothyroid muscle.

  • The cricothyroid is attached to the cricoid cartilage and the thyroid cartilage; contraction of this muscle tends to stretch and adduct the vocal ligament. The cricothyroid is innervated by the external laryngeal nerve.


Usmle neuroscience review

  • The lateral cricoarytenoid muscle (choice B) is innervated by the recurrent laryngeal nerve, and is attached to the cricoid cartilage and the arytenoid cartilage. Its contraction causes adduction of the vocal ligament.

  • The posterior cricoarytenoid muscle (choice C) is innervated by the recurrent laryngeal nerve, and is attached to the cricoid cartilage and the arytenoid cartilage. Its contraction causes abduction of the vocal ligament.

  • The thyroarytenoid muscle (choice D) is innervated by the recurrent laryngeal nerve, and is attached to the thyroid cartilage and the arytenoid cartilage. Its contraction causes slackening of the vocal ligament.

  • The vocalis muscle (choice E) is the most medial part of the thyroarytenoid muscle. It attaches to either the thyroid cartilage and the vocal ligament, or the arytenoid cartilage and the vocal ligament. It is innervated by the recurrent laryngeal nerve. Its contraction causes tension on segments of the vocal ligament.


Usmle neuroscience review

  • Retinoblastoma is associated with an abnormality in which chromosome?

  • A. 5

  • B. 8

  • C. 13

  • D. 21

  • E. X


The correct answer is c12

The correct answer is C.

  • About 20% of patients with chromosome 13 abnormality (13q-syndrome) develop retinoblastoma.

  • There is also a genetic dominant form of retinoblastoma that has an 80% penetrance rate.

  • Retinoblastomas that have a genetic basis are more apt to be bilateral than the spontaneous lesions.

  • Retinoblastomas are composed of masses of small hyperchromatic cells that may form small rosettes composed of radially arranged cells surrounding a central lumen.


Usmle neuroscience review

  • A slightly mentally retarded individual with menstrual irregularities is found to have a 47, XXX karyotype.

  • The average life span for individuals with this condition is

  • A. 10-20 years

  • B. 20-30 years

  • C. 30-40 years

  • D. 40-50 years

  • E. normal


The correct answer is e13

The correct answer is E.

  • 47, XXX is a surprisingly benign condition, the incidence of which is unknown because most cases are never diagnosed, as a normal phenotype with normal life span is typical.

  • There is some increase in the incidence of mental retardation and menstrual irregularities in the population, particularly with increasing numbers of supernumerary X chromosomes.

  • Presumably, the inactivation of the extra X chromosome (forming a second Barr body that may be observed on a buccal smear examined for other reasons) limits the expression of the extra genes.


Usmle neuroscience review

  • A 2-year-old girl is evaluated because of deteriorating vision. On physical examination, a whitish hue is noted in the right pupil, along with strabismus.

  • Palpation of the eye elicits apparent pain and tenderness. The patient is referred to an ophthalmologist, who schedules surgery, and removes a multifocal tumor from the right eye. The pathology report notes the presence of rosettes composed of cuboidal-to-columnar cells surrounding a central lumen in the tumor.

  • In all likelihood, this child's condition stems from a mutation in a gene on chromosome

  • A. 5 B. 7

  • C. 9 D. 13 E. 21


The correct answer is d8

The correct answer is D.

  • The description of this case is classic for retinoblastoma, the most common malignant eye tumor of childhood.

  • Retinoblastoma presents as in the question, and microscopically is composed of neuroepithelial cells that form characteristic rosettes (Flexner-Wintersteiner rosettes).

  • Familial retinoblastoma is often bilateral or multifocal, as in this case.


More detail on retinablastoma1

More detail on retinablastoma..

  • A preexisting mutation of a tumor suppressor gene, Rb, located on chromosome 13 (13q14) is present, but causes no symptoms. A second, somatic mutation in a retinal cell leads to loss of a nuclear protein that prevents the retinal cell from exiting G1, allowing development of the tumor.

  • In cases of sporadic retinoblastoma, mutations must occur in both chromosomes 13 of a somatic cell, a rare event, hence sporadic retinoblastoma is always unifocal and unilateral.


Usmle neuroscience review

  • A patient loses the ability to flex his forefinger. The nerve that supplies the muscles that cause this action is formed from which of the following cord(s) of the brachial plexus?

  • A. Lateral only

  • B. Medial and lateral

  • C. Medial only

  • D. Medial and posterior

  • E. Posterior only


The correct answer is b19

The correct answer is B.

  • The muscles involved are the flexor digitorum superficialis and the flexor digitorum profundus.

  • The flexor digitorum superficialis is completely supplied by the median nerve.

  • The flexor digitorum profundus is supplied by both the ulnar (little finger side) and median (thumb side) nerves. Flexion of the forefinger is consequently dependent on the median nerve, which is formed by part of both the medial and lateral cords of the brachial plexus.


Usmle neuroscience review

  • The lateral cord (choice A) alone supplies the musculocutaneous nerve.

  • The medial cord alone (choice C) supplies the ulnar nerve.

  • No nerve is supplied by both the medial and posterior cords (choice D).

  • The posterior cord alone (choice E) supplies the radial nerve.


Usmle neuroscience review

  • While riding his bicycle, a 16-year-old boy hits a rock and is thrown over the handlebars, striking the ground with his head and right shoulder.

  • He is wearing a helmet, and thus avoids significant head trauma, but he is brought to the emergency department by his parents.

  • On physical examination, the physician notes that the boy holds his right upper limb at rest with the palm facing posteriorly.

  • He is unable to abduct his arm at his shoulder and has diminished sensation over the lateral side of his arm. Which of the following neural structures was most likely injured?


Usmle neuroscience review

  • A. Axillary nerve

  • B. Lateral cord of the brachial plexus

  • C. Musculocutaneous nerve

  • D. Suprascapular nerve

  • E. Upper trunk of the brachial plexus


Usmle neuroscience review

  • The correct answer is E.

  • The patient sustained a traction injury to the upper trunk of the brachial plexus. The upper trunk is in the neck and contains nerve fibers from the anterior rami of the 5th and 6th cervical nerves, which pass in an inferolateral direction to reach the axilla.

  • The motor losses associated with this injury are termed "Erb's palsy." Typically affected are those muscles receiving motor innervation from the 5th and 6th cervical nerves, including the deltoid and the supraspinatus muscles, the two muscles responsible for abduction of the arm at the shoulder.


Usmle neuroscience review

  • In addition, all muscles responsible for external rotation at the shoulder (teres minor, infraspinatus, and the posterior portion of the deltoid) are affected.

  • Because the patient is unable to abduct or externally rotate his upper limb, it is held in the adducted and internally rotated position, resulting in the palm facing posteriorly (the porter's tip sign).

  • Finally, the sensory innervation of the lateral side of the arm and forearm is derived from the 5th and 6th cervical nerves.


Usmle neuroscience review

  • The axillary nerve (choice A) innervates the deltoid and teres minor muscles. Injury to this nerve would cause weakness in abduction and external rotation. However, the cutaneous sensory distribution of the axillary nerve is limited to the region of skin on the upper arm overlying the deltoid.

  • The axillary nerve forms in the axilla and leaves the axilla though the quadrangular space; it would not be injured by the type of trauma sustained by this patient, although it can be injured by fractures of the surgical neck of the humerus or dislocation of the glenohumeral joint.

  • The lateral cord of the brachial plexus (choice B) contains nerve fibers that innervate muscles in the anterior compartment of the arm and forearm. The cutaneous sensory distribution of these sensory fibers is to the lateral side of the forearm and the lateral portion of the palmar aspect of the hand. The lateral cord would not typically be injured by this type of accident.


Usmle neuroscience review

  • The musculocutaneous nerve (choice C) is a branch of the lateral cord. It innervates muscles of the anterior compartment of the arm and the skin on the lateral side of the forearm. This nerve would not typically be injured in this type of accident.

  • The suprascapular nerve (choice D) arises from the upper trunk and innervates the supraspinatus and infraspinatus muscles. The described symptoms would not be seen with an injury to this nerve.


Usmle neuroscience review

  • A previously healthy adult developed ataxia and began posturing. Eventually, he was demented and unable to care for himself. At autopsy, extensive cortical demyelination is observed. Microscopic examination of the areas of demyelination reveals numerous macrophages containing crystals that stain a light brown color with toluidine blue. This presentation is probably due to a deficiency of

  • A. arylsulfatase A

  • B. galactocerebroside b-galactosidase

  • C. glucocerebrosidase

  • D. hexosaminidase A

  • E. sphingomyelinase


The correct answer is a10

The correct answer is A.

  • The presentation and autopsy findings are consistent with metachromatic leukodystrophy.

  • The crystals in the macrophages that stained brown with toluidine blue are sulfatides, which accumulate in this disorder.

  • The color shift seen in the toluidine blue stain is termed metachromasia (hence the term metachromatic leukodystrophy).

  • The cause of metachromatic leukodystrophy is deficiency of arylsulfatase A.


Usmle neuroscience review

  • Galactocerebroside b-galactosidase (choice B) deficiency produces Krabbe's disease. In this disorder, multinucleated cells derived from macrophages (globoid cells) are seen around blood vessels. Electron microscopy of the macrophages reveals the presence of linear inclusions.

  • Glucocerebrosidase (choice C) deficiency results in Gaucher's disease, characterized by accumulation of glucocerebrosides. Gaucher's cells are cells distended with material that resembles crumpled tissue paper.


Usmle neuroscience review

  • Hexosaminidase A (choice D) deficiency is associated with Tay Sachs disease, characterized by accumulation of GM2 ganglioside in the central and autonomic nervous systems.

  • Sphingomyelinase deficiency (choice E) produces Niemann-Pick disease, in which sphingomyelin accumulates, especially in cells of the mononuclear phagocytic system.


Usmle neuroscience review

  • A physician asks a patient to hold her right upper arm close to her lateral chest wall, and bend the arm at the elbow so that the palm is facing upward.

  • The physician then directs the patient to turn her hand so that the palm faces downward, without bending her wrist.

  • This maneuver causes discomfort to the patient, which the physician notes as pain on

  • A. abduction of the forearm

  • B. adduction of the forearm

  • C. flexion of the forearm

  • D. pronation rotation of the forearm

  • E. supination rotation of the forearm


The correct answer is d9

The correct answer is D

  • When the forearm is rotated from anatomic position so that the palm faces posteriorly, the forearm is said to be pronated.

  • Abduction (choice A) raises the arm to a horizontal position away from the body; adduction (choice B) is the reverse.

  • Flexion (choice C) brings the arm or forearm forward, in front of the plane of the body.

  • Rotation of the forearm so that the palm faces forward (i.e., into anatomic position) is referred to as supination (choice E).


Usmle neuroscience review

  • A 10-year-old boy was noted for his extreme fear of water during his first day of swimming lessons. The teacher helps the child sit on the edge of the pool and splash the water with his feet.

  • She then goes one step further and shows him how to wet his knees. It takes her an hour to have him float on the water while holding his hand.

  • What technique has the teacher used to help the child conquer his fear of water?

  • A. Classical conditioning

  • B. Desensitization

  • C. Extinction

  • D. Flooding

  • E. Operant conditioning


The correct answer is b20

The correct answer is B.

  • Desensitization is an effective therapy for phobia. The therapist models and guides the patient through progressive steps, starting with the least fearful step until the fear and anxiety associated with phobic object is extinguished.

  • In classical conditioning (choice A), which was first described by Pavlov in animal models, a neutral stimulus is paired with a stimulus that produces a response.

  • The goal is to have the neutral stimulus alone produce the response. If food and the ringing of a bell produces salivation in a dog, repeated conditioning will cause salivation in the dog upon hearing the bell alone.


Usmle neuroscience review

  • The goal in extinction (choice C) is to change a response by denying a reward that has maintained that response. If a child gets his parents' attention by misbehaving, not paying attention to him can produce extinction of the misbehavior.

  • In flooding (choice D), the therapist encourages the patient to confront the feared object or situation without a gradual or graded exposure.

  • In operant conditioning (choice E), the goal is to increase the likelihood of a response by reinforcement. A desired behavior is rewarded so it will be repeated and strengthened.


Usmle neuroscience review

  • In which of the following sites do myxopapillary ependymomas most frequently occur?

  • A. Cerebellum

  • B. Conus medullaris

  • C. 4th ventricle

  • D. Lateral ventricles

  • E. Midbrain


The correct answer is b21

The correct answer is B

  • Myxopapillary ependymoma is a variant of ependymoma, a tumor arising from ependymal cells.

  • Histologically, myxopapillary ependymoma contains a myxoid (mucus-rich) intercellular matrix, in which spindly neoplastic ependymal cells are arranged in a fascicular and papillary pattern (hence its designation).

  • It is a benign tumor that almost always occurs in the distal segment of the spinal cord, ie, the conus medullaris.

  • Once excised, the patient is cured.


Usmle neuroscience review

  • What is the earliest age at which toilet training is likely to be successful?

  • A. 10 months

  • B. 13 months

  • C. 16 months

  • D. 19 months

  • E. 22 months


The correct answer is d10

The correct answer is D.

  • Toilet training is not possible before the age of 18 months because the long nerve fibers have not yet myelinated and sphincter control is not possible.

  • Toilet training should be completed by 4 years of age.


Usmle neuroscience review

  • A 15-year-old is brought to the emergency department in a coma. An alert ambulance attendant notes that the patient's breath smells like acetone. This would be most consistent with which of the following?

  • A. Alcohol intoxication

  • B. Diabetic hyperosmolar coma

  • C. Diabetic ketoacidosis

  • D. Heroin overdose

  • E. Profound hypoglycemia


The correct answer is c13

The correct answer is C.

  • The smell of acetone on the breath of a comatose patient is an important, rapid diagnostic clue that strongly suggests ketoacidosis and is usually seen in patients with poorly controlled type 1 diabetes.

  • Other features of diabetic ketoacidosis include high blood glucose, increased serum osmolality, hypovolemia, acidosis, and electrolyte imbalance.


Usmle neuroscience review

  • In alcohol intoxication (choice A), the breath will smell like alcohol.

  • Diabetic hyperosmolar coma (choice B) usually is seen in older patients with type 2 diabetes and is not characterized by ketoacidosis. Since there is no acetone production, there is no specific scent to the breath.

  • In heroin overdose (choice D), no acetone production occurs and there is no specific scent to the breath.

  • In hypoglycemic coma (choice E), which can occur in diabetics with insulin overdose, no acetone production occurs and there is no specific scent to the breath.


Usmle neuroscience review

  • The cerebellum (choice A) is the favorite site for pilocytic astrocytomas, medulloblastomas, and hemangioblastomas, but not ependymomas.

  • In general, classic ependymomas occur in close proximity to the ventricular cavities, specifically, the 4th ventricle (choice C) in children and the lateral ventricles (choice D) in adults.

  • The myxopapillary variant does not occur in either location.

  • A midbrain location (choice E) would be truly exceptional for any type of ependymoma.


Usmle neuroscience review

Speech Deficits with lesion at:

3

1

2

1: Broca’s area: labored speech, understanding intact

2: Wernicke’s area: nonsensical speech, no understanding

3: Arcuate fasciculus fibers: nonsensical speech, understanding intact


Usmle neuroscience review

Functional Associations with:

1

3

2

4

5

1: paracentral lobule - leg movement and sensation

2: cuneate gyrus - contralateral lower visual field

3. cingulate gyrus - emotional component of pain

4. Thalamus - sensory relay nuclei (e.g. VPL & VPM, LGN)

5. Hypothalamus - sympathetic projections to IML column of thoracic spinal cord


Usmle neuroscience review

4

3

1

2

1: Uncus 2: Amygdala 3: Insula 4: Corpus callosum


Usmle neuroscience review

Human Spinal Cord X-Sections at Different Levels

Cervical

enlargement

Thoracic

Sacral

Lumbar


Usmle neuroscience review

thalamus hippocampus


Usmle neuroscience review

Function ?

Function ?

Caudate or thalamus?

Caudate

Audition

Amygdala

(Emotions)


Usmle neuroscience review

MLF

periaqueductal gray

medial lemniscus

CST and CBT in

cerebral peduncle

Functional Associations:


Usmle neuroscience review

Where Am I?

Function?

Lesion here?

MLF- Coordinates nuc. III, IV & VI

Fine touch, etc. and P & T to contralateral body and face

Which artery supplies this cross section?

Atlas #16

Basilar


Usmle neuroscience review

Identify

MLF

Abducens nuc

PPRF


Usmle neuroscience review

Identity & Location?

Decussation of the pyramidal (corticospinal) tract medullary/ spinal cord junction


Usmle neuroscience review

Optic tract

Optic nerve

Meyer’s Loop

Lateral Geniculate

Nucleus

Lingula (upper visual field)

Cuneus (lower visual field)

Left Visual Field

Right Visual Field


Usmle neuroscience review

Visual Field Defect?

Contralateral (right) homonymous hemianopsia

Contralateral (left) upper quadrantanopsia


Usmle neuroscience review

Left

Right

Where is the lesion?

Bitemporal hemianopsia

Middle of optic chiasm


Usmle neuroscience review

Left

Right

Where is the lesion?

Left homonymous hemianopsia (with macular sparing)

Right primary visual cortex or optic radiations


Usmle neuroscience review

Left

Right

Where is the lesion?

Blind in left eye

Left eye or optic nerve


Usmle neuroscience review

Left

Right

Where is the lesion?

left homonymous upper quadrantanopsia

right lingula (or right Meyer’s loop)


Usmle neuroscience review

Posterior

Commissure

To

constrictors

Control of

Pupillary Size

To

dilators

RGC

Ciliary

ganglion

Parasympathetic

Constriction

O.C.

LGN

N. III

Pretectal

Area

Edinger-Westphal

Nucleus

Sympathetic

Dilation

Superior Cervical

Ganglion

Intermediolateral

Cell Column

(MFB provides descending

input to sympathetic

preganglionics of IML)


Usmle neuroscience review

Third Nerve or Nucleus

Down and out

Dilated pupil

Drooping eyelid (ptosis)

Horner’s Syndrome

Constricted pupil (miosis)

Slight drooping eyelid (ptosis)

Anhydrosis


Usmle neuroscience review

Light Shined into:

Right Eye Left Eye

no direct yes direct

no consensual yes consensual

Right optic nerve or globe


Usmle neuroscience review

Light Shined into:

Right Eye Left Eye

no direct yes direct

yes consensual no consensual

Right N. III


What is an argyll robertson pupil

What is an Argyll-Robertson Pupil?

Pupils canaccommodate

but are unreactive to light


Usmle neuroscience review

Right Left

RightLeft

Medial Rectus

Lateral Rectus

N

1

2

3

4

2

Nuc III

1

3

MLF

Nuc VI

footnote: damage to right nuc. VI would in addition change resting position of right eye

4

PPRF

“Look to

the Right”

input from

frontal eye fields


Usmle neuroscience review

“Look Right”

Where is the most likely lesion?

left nerve III


Usmle neuroscience review

“Look Right”

Where is the lesion?

medial longitudinal fasiculus (MLF)


Usmle neuroscience review

“Look Right”

Where is the lesion?

right abducens nerve (VI)


Usmle neuroscience review

“Look Right”

Where is the most likely lesion?

Right PPRF

(or left frontal eye field axons)


Usmle neuroscience review

Postcentral Gyrus

Arm

Leg

VPL

Internal

Capsule

Medial Lemniscus

Dorsal Column Nuclei

(Gracile & Cuneate)

Dorsal Column / Medial Lemniscal System

3rd

  • Summary

  • Large myelinated dorsal root fibers

  • Fine touch, etc. from legs, trunk and arms

  • Enter spinal cord medial to small dorsal root fibers

  • Two synaptic relays:

    • 1) low medulla

    • 2) VPL of thalamus

  • Decussation in low medulla

  • Destination: leg and arm regions on somatosensory homunculus

2nd

1st


Usmle neuroscience review

What sensory functions are mediated by the

dorsal column-medial lemniscus system?

Fine touch:

includes ability to sense vibration,

+stereoagnosis and graphesthesia

Proprioception:

includes static position sense and

dynamic position sense (=kinesthesia)


Neurological findings on motor exam of patient with right high cervical hemisection

Neurological Findings on motor exam of patient with right high cervical hemisection

  • Early sign?

    • Ipsilateral flaccid paralysis of arms and legs

      (hemiplegia - i.e., complete paralysis)

  • Late signs?

    • Ipsilateral Babinski reflex

    • Ipsilateral spastic paralysis of arms and legs

    • Ipsilateral hypereflexia


Cns hemorrhage

CNS Hemorrhage

  • Epidural - between dura mater and skull (esp. fractures of temporal skull, which can rupture middle meningeal artery)

  • Subdural - between dura and arachnoid (esp. with shearing of bridging veins)

  • Subarachnoid - between arachnoid and pia

    (can give bloody csf)


Usmle neuroscience review

How was this image obtained?

Radiopaque media into right internal carotid artery

Perfusion on left is normal.


Usmle neuroscience review

Pons

Mid-medulla

Caudalmedulla


Usmle neuroscience review

Basilar artery branches (long

circumferential

such as AICA)

Basilar artery branches (short

circumferential)

Basilar artery

branches (paramedian)

Pons


Usmle neuroscience review

Brown Sequard Syndrome

  • Impairment of ipsilateral light touch, proprioception and vibration (dorsal columns) from site of lesion, caudally

  • Impairment of contralateral pain and temperature (spinothalamic tract) below level of lesion

  • Impairment of ipsilateral voluntary movements below level of lesion

  • if above T1/T2, ipsilateral Horner’s syndrome


Usmle neuroscience review

Cyst in ventral white commissure

Syringomyelia -- Cyst in ventral whitecommissure

  • Bilateral impairment in pain and temperature forming a band across the body at the level of the cyst


Usmle neuroscience review

Tabes Dorsalis

Tabes Dorsalis

  • A syndrome associated with syphilis

  • Degeneration of large diameter myelinated fibers and their cell bodies

  • Bilateral impairment in light touch, proprioception and vibration.

  • Pain and temperature sensations are unaffected


Usmle neuroscience review

Posterior Spinal Artery Occlusion

  • Impairments of light touch, proprioception and vibration, ipsilaterally from level of interruption caudally


Usmle neuroscience review

Anterior spinal artery obstruction

  • Deficits:

  • Pain and temp bilaterally below lesion (spinothalamic tract)

  • Bilateral loss of voluntary movement below level of lesion

  • spinal reflexes lost at the level of the obstruction, but not below it

  • If above T1/T2, Horner’s syndrome bilaterally


Usmle neuroscience review

Posterior Spinal Artery(Medulla)

  • Ipsilateral impairment of light touch, proprioception and vibration (nucleus gracilis and cuneatus)


Usmle neuroscience review

PICA occlusionLateral Medullary Syndrome

  • Contralateral impairment of pain and temperature on the body (spinothalamic tract)

  • Ipsilateral impairment of pain and temperature on the face (spinal trigeminal nucleus and tract)


Usmle neuroscience review

Medial Pontine Syndrome(Occlusion of paramedian

branches of the Basilar artery)

  • Impaired movement of contralateral arm and leg, upper motor neuron syndrome (corticospinal tract).

  • Impaired lateral movement of ipsilateral eye (N. VI). Sometimes PPRF can also be affected.

  • May have contralateral impairment of light touch, proprioception and vibration (medial lemniscus).


Usmle neuroscience review

Lateral Pontine Syndrome(Occlusion of AICA)

  • Impaired sensation on ipsilateral face (trigeminal nuclei).

  • Facial paralysis ipsilaterally (nerve and nuc. of VII).

  • Impaired pain and temperature on contralateral body (spinothalamic tract).

  • Impaired horizonal gaze (abducens and PPRF).


Usmle neuroscience review

N. VII

Lesion in Internal Capsule

Lesion in Internal Capsule

  • Impairments of light touch, proprioception, vibration, pain and temperature for contralateral body and face

  • Contralateral loss of voluntary movement in the body and face … except ...

  • Upper face spared due to bilateral cortical innervation of facial nucleus upper face neurons.


Usmle neuroscience review

Infarct of the Basilar Artery

(Paramedian Branches)


Usmle neuroscience review

Medial Pontine Syndrome

Basilar (paramedian) infarct

  • Deficits:

  • contralateral motor impairment to arm and leg (LCST)

  • contralateral impairment of fine touch, etc. to arm and leg (ML)

  • inward deviation of ipsilateral eye (nerve VI)

  • possible inability to look ispsilaterally to side of lesion (PPRF)


Usmle neuroscience review

What Sensory Modality?

Pain and Temp

Sp. Nuc and Tr V

Spinothalamic Tr

Part of Lateral Pontine Syndrome

(We will complete this after the midterm)


Usmle neuroscience review

Deficits?

Decrease in fine touch, etc. and movement in contralateral body

Branch of

Anterior spinal artery

Blood Supply?


Usmle neuroscience review

Blood supply?

Deficits?

P & T, ipsilateral face, contralateral body, ipsilateral Horner’s syndrome

Branch of thevertebral artery


Usmle neuroscience review

Location and Nature of Deficit?

Ipsilateral arm and hand;

decreased fine touch, vibratory,

proprioception, and discriminative

touch (e.g., stereognosis)


Usmle neuroscience review

Deficits and Blood Supply?

Deficits &

Blood Supply?

Deficits & Blood Supply?

Touch, etc. in ipsilateral body posterior spinal art.

P&T ipsilateral face, contralateral body; Horners’s - vertebral art.

(spinal tract of ; spinothalamic tract; hypothalamospinal tract)

Bilateral touch, etc. and movement of body - ant. spinal artery (pyramids and a bit of the ML)


Usmle neuroscience review

Artery and Deficit?

Rostral or Caudal to Previous Slide?

Caudal

Anterior spinal artery ; bilateral motor deficit below lesion (LCST)


Usmle neuroscience review

Deficits?

Ipsilateral Horner’s; Ipsilateral motor deficit to arm and leg

Syringomyelia; loss of P&T in band around chest


Usmle neuroscience review

3 Causes?

1) Post. spinal art. infarct

2) B12 deficiency (pernicious anemia)

3) tabes dorsalis


Usmle neuroscience review

Deficit?

Decreased P&T in contralateral leg


Usmle neuroscience review

HRP here goes where retrogradely?

1

Neurons here terminate where?

3

2

4

3-contralateral lumbar ventral horn

4-brainstem bilaterally

ipsilateral

1-VPL 2-VPM


Usmle neuroscience review

HRP here would be found where?

Contralateral precentral gyrus and red nucleus


Neurological findings on motor exam of patient with right high cervical hemisection1

Neurological Findings on motor exam of patient with right high cervical hemisection

  • Early sign?

    • Ipsilateral flaccid paralysis of arms and legs

      (hemiplegia - i.e., complete paralysis)

  • Late signs?

    • Ipsilateral Babinski reflex

    • Ipsilateral spastic paralysis of arms and legs

    • Ipsilateral hypereflexia


Usmle neuroscience review

If we . . .

Inject HRP (retrograde label) into the right postcentral gyrus

We would see staining of . . .

Right VPL and VPM nuclei of the thalamus


Usmle neuroscience review

If we . . .

Inject HRP (retrograde label) into VPL of one thalamus

We would see staining of . . .

Contralateral dorsal column nuclei and dorsal horn of the spinal cord


Usmle neuroscience review

If we . . .

Inject HRP (retrograde label) into dorsal column nuclei on one side

We would see staining of . . .

ipsilateral dorsal root ganglia


Usmle neuroscience review

If we . . .

remove the right VPL of the thalamus

We would see degenerating terminals in...

The right postcentral gyrus


Usmle neuroscience review

If we . . .

Inject anterograde label unilaterally into dorsal column nuclei

We would see staining of . . .

the contralateral VPL nucleus of the thalamus


Usmle neuroscience review

If we . . .

Destroy the right red nucleus

We would see degenerating terminals in . .

The contralateral ventral gray matter of cervical spinal cord


  • Login