Hydrocephalus
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Hydrocephalus. Definition-Hydrocephalus is a disorder in which the cerebral ventricular system contains an excessive amount of cerebrospinal fluid (CSF) and is dilated because of increased pressure PHYSIOLOGY CSF is produced - choroid plexus.

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Hydrocephalus

Definition-Hydrocephalus is a disorder in which the cerebral ventricular system contains an excessive amount of cerebrospinal fluid (CSF) and is dilated because of increased pressure

PHYSIOLOGY

CSF is produced - choroid plexus.

circulates through the ventricular system & absorbed into the systemic circulation




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  • CSF production —

  • Choroid plexus - located in the cerebral ventricles.

    - consists of villous folds lined by epithelium with a central core of highly vascularized connective tissue.

    - produces CSF by active secretion and diffusion.

  • The production rate of adults is approximately 20 mL/hour, turnover 3 – 4x/ d, less in newborns- children

  • The volume - infants is = 50 mL & 150 mL adults & in adults, 25 percent is within the ventricular system.

  • CSF formation continues in raised intracranial pressure unless extremely high


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  • Ventricular system —

  • comprised of lateral ventricles connected via foramen of Monro to the midline third ventricle.

  • third ventricle is connected to fourth ventricle aqueduct of Sylvius.

  • Three exits from the fourth ventricle, the paired lateral foramina of Luschka and a midline foramen of Magendie, lead to a system of interconnecting and focally enlarged areas of subarachnoid spaces known as cisterns. The cisterns in the posterior fossa connect to the subarachnoid spaces over the cerebral convexities through pathways that cross the tentorium. The basal cisterns connect the spinal and intracranial subarachnoid spaces.

  • CSF absorption — CSF flows from the lateral ventricles to the third and fourth ventricles and then through the basal cisterns, tentorium, and subarachnoid space over the cerebral convexities to the area of the sagittal sinus. The net flow of CSF in the spinal subarachnoid space is cephalad.

  • CSF is absorbed via arachnoid villi into the venous channels of the sagittal sinus. Some CSF absorption also occurs across the ependymal lining of the ventricles and from the spinal subarachnoid space.




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  • PATHOGENESIS —

  • imbalance - the production and absorption of CSF.

  • principal mechanism is deficient absorption= from a mechanical or functional obstruction to the flow of CSF= excessive volume of CSF = increased ventricular pressure dilatation.

  • CSF production continues resulting in extreme elevations of intracranial pressure that preclude neurologic function and survival.

  • Three mechanisms of imbalance of CSF formation and absorption: 1.obstruction of CSF pathways

    2. impaired venous absorption

    3. oversecretion of CSF.

    The disorder that results from obstruction of the ventricular system is known as obstructive, or noncommunicating, hydrocephalus Communicating hydrocephalus occurs when the subarachnoid pathways are blocked. CSF production is nearly always normal.


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  • Obstruction —

  • Anatomic or functional obstruction - most common mechanism

  • The obstruction occurs at the foramen of Monro, the aqueduct of Sylvius, or the fourth ventricle and its outlets

  • Dilatation of the ventricular system occurs proximal to the block. Obstruction of one foramen of Monro results in dilatation of the lateral ventricle on that side

  • If the aqueduct of Sylvius is blocked- lateral and third ventricles dilate, while fourth ventricle remains relatively normal.

  • Impaired absorption — A less common mechanism due to inflammation of the subarachnoid villi. This results in communicating hydrocephalus, in which the entire ventricular system is dilated.

  • Excessive production — of CSF is a rare cause of hydrocephalus, may occur with a functional choroid plexus papilloma and leads to enlargement of the entire ventricular system.


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  • PATHOPHYSIOLOGY — Acute obstruction= increased pressure and rapid enlargement of the ventricular system.

  • The frontal and occipital horns of the lateral ventricles enlarge first.

  • flattening of gyri & compression of the sulci, obliteration of the subarachnoid

  • The vascular system is compressed, & the venous pressure in the dural sinuses increases

  • Ventricular enlargement =thinning of the cerebral mantle& disrupts the ependymal lining = CSF move directly into brain tissue = alternate route of CSF absorption that may limit further dilatation & contributes to the development of interstitial edema of the periventricular white matter.

    compensatory mechanism is spreading of the cranial sutures

  • Intracranial pressure is less in chronic hydrocephalus = the force of is distributed over the greater surface area


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  • PATHOLOGY — ventricular dilatation before fusion of the cranial sutures = enormous enlargement of the head

  • The intracranial pressure increases more slowly

  • Marked head enlargement not occur if hydrocephalus occurs acutely or after fusion of sutures= significantly ICP

  • ventricular dilatation results in atrophy of the white matter= caused by tissue ischemia from the edema and increased intraventricular pressure.

  • The width of the cerebral mantle may be reduced, gray matter is better preserved than white matter, even in advanced stages.

  • congenital CNS abnormalities like cortical dysplasias, pachygyria, and polymicrogyria, are associated with X-linked hydrocephalus


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  • A.Congenital — hydrocephalus can result from CNS malformations (which include nonsyndromic and syndromic disorders), infection, trauma, and teratogens- rare cause is obstruction by a congenital CNS tumor, located near the midline.

  • Neural tube defects — majority with myelomeningocele have hydrocephalus. =obstruction of fourth ventricular outflow or flow of CSF through the posterior fossa due to the Chiari malformation or an associated aqueductal stenosis.

  • Isolated hydrocephalus — by aqueductal stenosis due to congenital narrowing of the aqueduct, or intrauterine infection.

  • X-linked hydrocephalus — most common genetic form of congenital hydrocephalus with stenosis of the aqueduct of Sylvius (HSAS)]. Approximately 50% affected boys have adducted thumbs. Some have other CNS abnormalities such as agenesis or dysgenesis of the corpus callosum, small brainstem, or absence of the pyramidal tract.

  • is due to mutations in the gene encoding L1, a neuronal cell adhesion molecule that belongs to the immunoglobulin superfamily and is essential in neurodevelopmen. The gene for L1 has been mapped to Xq28. Mutations in L1 also result in other conditions, known as the L1 spectrum, that are characterized by neurologic abnormalities and mental retardation. These include MASA spectrum (Mental retardation, Aphasia, Shuffling gait, Adducted thumbs), X-linked spastic paraplegia type 1, and X-linked agenesis of the corpus callosum.


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  • CNS malformations — frequently associated with hydrocephalus.

  • Chiari malformation, accompanies a neural tube defect, the brain stem and cerebellum- displaced caudally obstructing the flow of CSF in the posterior fossa

  • The Dandy-Walker malformation consists of a large posterior fossa cyst continuous with the fourth ventricle and defective development of the cerebellum, including partial or complete absence of the vermis =secondary obstruction of the foramina of Luschka and Magendie.

  • Vein of Galen malformation is a rare cause = compression of the aqueduct of Sylvius by the markedly dilated and distorted vein .

  • Syndromic forms - The most frequent are trisomies 13, 18, 9 and 9p, and triploidy

  • Intrauterine infection -rubella, cytomegalovirus, toxoplasmosis, and syphilis = inflammation of the ependymal lining of the ventricular system and the meninges in the subarachnoid space = obstruction of CSF flow through the aqueduct or basal cisterns.

  • Acquired hydrocephalus — Common are CNS infections - bacterial meningitis or viral infections including mumps, and tumors, especially posterior fossa medulloblastomas, astrocytomas, and ependymomas.

  • Another cause is hemorrhage into the subarachnoid space or, less commonly, into the ventricular system, by ruptured aneurysms, arteriovenous malformations, trauma, or systemic bleeding disorders= induces an inflammatory response followed by fibrosis, obstructing the flow and/or absorption of CSF.

  • Posthemorrhagic hydrocephalus occurs in approximately 35 percent of preterm infants with intraventricular hemorrhage (IVH). It can be obstructive, communicating, or both, and can be transient or sustained, with slow or rapid progression.




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  • CLINICAL FEATURES — signs and symptoms result from:

    - increased ICP and dilatation of the ventricles

    -time of presentation depends upon the acuity of the process.

  • Symptoms are nonspecific and independent of the etiology

  • Headache is a prominent symptom. It is caused by distortion of the meninges and blood vessels. The pain often varies in intensity and location and may be intermittent or persistent. Headaches due to increased ICP often occur in the early morning and are associated with nausea and vomiting

  • often have changes in their personality and behavior (irritability, obstreperousness, indifference, and loss of interest), mechanism is uncertain, but related in part to increased ICP. As the hydrocephalus worsens, midbrain and brain stem dysfunction may result in lethargy and drowsiness.

  • Increased ICP in the posterior fossa often leads to nausea, vomiting, and decreased appetite.


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  • In infants, common signs and symptoms of hydrocephalus include:

  • An unusually large head

  • A rapid increase in the size of the head

  • A bulging "soft spot" on the top of the head (anterior fontanel)

  • Vomiting

  • Sleepiness

  • Irritability

  • Seizures

  • Eyes fixed downward (sunsetting of the eyes)

  • Developmental delay


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In older children and adults, common signs and symptoms of hydrocephalus include:

  • Headache followed by vomiting

  • Nausea

  • Blurred or double vision

  • Eyes fixed downward (sunsetting of the eyes)

  • Problems with balance, coordination or gait

  • Sluggishness or lack of energy

  • Slowed development or loss of development

  • Memory loss

  • Urinary incontinence

  • Irritability

  • Change in personality


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  • Physical examination — Physical findings are due to the effects ICP.

  • Distortions of the brainstem may result in changes in vital signs such as bradycardia, systemic hypertension, and altered respiratory rate.

  • Excessive head growth & ventricular dilatation occur before head growth becomes abnormal.

  • The anterior fontanelle may become full or distended.

  • Young infants may develop frontal bossing, an abnormal skull contour in which the forehead becomes prominent.

  • The scalp veins may appear dilated and prominent.

  • Compression of the third or sixth cranial nerve may result in extraocular muscle pareses leading to diplopia. Pressure on the midbrain may result in impairment of upward gaze. This is known as the setting-sun sign because of the appearance of the sclera visible above the iris.

  • Fundoscopic examination may reveal papilledema.

  • Stretching of the fibers from the motor cortex around the dilated ventricles may result in spasticity of the extremities, especially the legs.

  • Accelerated pubertal development, as well as disturbed growth and fluid and electrolyte homeostasis, may result from pressure of the dilated third ventricle on the hypothalamus


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  • DIAGNOSIS — suspect in an infant whose head circumference is enlarged at birth, or when serial measurements cross growth curves,

  • In some cases, the diagnosis is made by antenatal ultrasonography. Hydrocephalus should be considered in children with severe headache and other features suggesting increased ICP

  • The diagnosis is confirmed by neuroimaging.

  • In older infants and children, CT or MRI should be performed. Neuroimaging studies will also detect associated CNS malformations or tumors.

  • The site of obstructed CSF flow may be suggested by the pattern of ventricular dilatation. Stenosis of the aqueduct typically results in dilated lateral and third ventricles and a fourth ventricle of normal size. In contrast, an extraventricular obstruction usually results in symmetric dilatation of all ventricles.

  • A lumbar puncture (LP) should be performed and the CSF should be examined if an infection causing adhesive arachnoiditis or ependymitis is suspected. However, LP is contraindicated if the patient has evidence of a space-occupying lesion such as an intracranial tumor or a brain abscess, because of the risk of cerebral herniation.


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  • MANAGEMENT — The most effective is surgical drainage- does not cure but treat the symptoms and stops progression.

  • Shunt — A mechanical shunt system involves placement of a catheter into one of the lateral ventricles, usually the right

  • The catheter is connected to a one-way valve system (usually placed beneath the scalp of the postauricular area) that opens when the pressure in the ventricle exceeds a certain value

  • ventriculoatrial, VA or ventriculoperitoneal, VP


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Hydro -Fig .VP & VA shunts


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  • Complications

  • The severity of hydrocephalus depends on the time of onset and whether the disease is progressive. If the condition is well advanced at birth, major brain damage and physical disabilities are likely. In less severe cases, with proper treatment, it's possible to have a nearly normal life span and intelligence.

  • Other complications of hydrocephalus include:

  • Intellectual impairment

  • Neurological damage, such as decreased function, movement or sensation

  • Problems with the artificial CSF drainage channel (surgical shunt), such as a blockage or kinking of the shunt tubing

  • Infection at the site of the shunt


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  • Complications — In general, complications of treated hydrocephalus are due to malfunction of the shunt. If the hydrocephalus is still active, symptoms recur and another drainage procedure is required. Shunt revision is unnecessary in rare cases when alternate pathways of absorption develop or normal mechanisms for handling CSF become reestablished, resulting in compensation or spontaneous arrest of the hydrocephalus.

  • Malfunction is due to infection or mechanical failure Approximately 40 percent of standard shunts fail within the first year after placement .


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  • Infection — Shunt infection is common = 5 to 10 percent of procedures . may be higher in newborns . Most occur in the first six monthst. Ventriculitis may develop.

  • organisms are own skin flora, such as Staphylococcus epidermidis, less frequently S. aureus, enteric bacteria, diphtheroids, and Streptococcus species .

  • Infection must be considered with a shunt & persistent fever. Antibiotics should be started, but alone is usually not effective. In most cases, an infected shunt must be removed and an external ventricular drain temporarily placed.

  • Shunt infections may promote the development of loculated compartments of CSF and contribute to impaired cognitive outcome and death . Perioperative antibiotic prophylaxis in a meta-analysis of 12 trials in 1359 patients, reduced the risk of subsequent shunt infection by 50 percent.

  • Mechanical failure — The failure rate (including infection) is approximately 40 percent in the first year, and 5 percent in subsequent years .

  • The majority of first shunt failures result from obstruction at the ventricular catheter. This is because shunts typically overdrain, greatly reducing the size of the ventricles=catheter to lie against the ependyma and choroid plexus which block the holes at the end of the catheter.

  • Fractured tubing is the cause in 15 percent of cases . Other causes include migration of part or all of the shunt (7.5 percent) and problems with overdrainage (7 percent).


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  • Third ventriculostomy — Endoscopic third ventriculostomy (ETV), perforation is made to connect the third ventricle to the subarachnoid space, in the initial treatment of selected cases of obstructive hydrocephalus and as an alternative to shunt revision. The success depends upon the cause and previous complications

  • Medical therapy — diuretics, fibrinolysis, and serial lumbar punctures- have significant complications and are less effective than surgical treatment.

  • Diuretics — The diuretics furosemide and acetazolamide decrease CSF production. They have been used for short periods in slowly progressive hydrocephalus in patients too unstable for surgery. Diuretics are also used in newborns with posthemorrhagic hydrocephalus, although their use is controversial .

  • A systematic review by the Cochrane database examined two eligible trials of diuretic therapy in newborns . These trials included 177 and 16 infants with posthemorrhagic ventricular dilation. The administration of acetazolamide and furosemide did not decrease the risk for VP shunt or the combined outcome of shunt or death. In the larger trial, the administration of acetazolamide and furosemide was associated with a borderline increase in the risk for motor impairment at one year (relative risk 1.27) . However, the combined outcome of delay, disability or motor impairment among survivors, or the risk of the combined outcome of death, delay, disability or impairment at one year were not affected. Diuretic treatment significantly increased the risk of nephrocalcinosis.


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  • Fibrinolytic therapy — Intraventricular administration of fibrinolytic agents has been used in newborns with posthemorrhagic hydrocephalus in an attempt to prevent permanent obstruction to CSF flow. This treatment does not appear to reduce the need for shunt placement and may increase the risk of hemorrhage, but adequate trials are lacking

  • Serial lumbar punctures — Repeated lumbar punctures - as a temporizing measure in preterm infants with posthemorrhagic hydrocephalus

  • In cases of rapidly progressive hydrocephalus, a temporary ventricular drainage device may be needed until a permanent shunt can be placed or the hydrocephalus resolves spontaneously


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  • OUTCOME — depends upon the etiology, associated abnormalities, and complications such as infection.

  • Survival — untreated -50 percent die before three years and 77 to 80 percent die before reaching adulthood Treatment( if no tumor) with 89 and 95 percent survival

  • Epilepsy — occur frequently in children with shunted hydrocephalus.

  • Seizures are associated with poor cognitive outcome

  • Functional outcome — depends upon prematurity, CNS malformations, other congenital abnormalities, epilepsy, and sensory and motor impairments

  • In a report from France, outcome at 10 years was evaluated in 129 consecutive children with hydrocephalus without tumor who had shunt placement before two years of age . Motor deficits, visual or auditory deficits, and epilepsy occurred in 60, 25, and 30 percent of patients, respectively. IQ was >90 in 32 percent and <50 in 21 percent. Attendance at a normal school was possible for 60 percent, although one-half were one to two years behind for their age or having difficulties. Of the remainder, 31 percent were in special classes or institutionalized and 9 percent were not considered educable.

  • In a series from the United Kingdom, 155 children with shunted hydrocephalus were followed for 10 years or until death (which occurred in 11 percent) . For survivors until school age, 59 percent attended a normal school. Children with hydrocephalus caused by infection or IVH were more likely to need special school than those with congenital hydrocephalus (52 and 60 versus 29 percent).


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Case history

  • Age 15yr/M sudent, Mersa

  • C/C behavioral change/1&1/2 years

  • Irritable, over talkative, aggression asaultive, grandiose, crying

  • Headache, vomiting, weakness, sweating

  • Repeated attacks of ear discharge

  • Failure to thrive

  • Got worse 8-months back-scaly lesions over skin-Desse H/L-ART

  • Gait change & imbalance-6 months-visual complaint

  • Recent enuresis but no incontinence

  • Negative symptoms


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History contd

  • Development –non remarkable

  • He used to be calm & good student

  • Family-father died cough & empyemia-9mon

  • Mother on ART, 4-other siblings-one younger sister healthy


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Physical finding

  • GA- Chronically sick

  • V/S-B/P __ P/R=78, T=36.7

  • scaly multiple lesions over scalp, LAP

  • Labile mood, appropriate affect, has insight

  • RT-6th N- palsy


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Lab -

  • WBC=3,600, 3,100/ml

  • HCT=34.1%, 32.4%

  • Platelet=214,000, 122,000/ml

  • ESR=102mm/hr, 120mm/hr

  • U/S-abdomen-Normal

  • RFT & LFT-normal

  • CT-scan


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