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The Central Nervous System. Cellular Responses to Injury. Reactions of neurons to injury Acute neuronal injury – “red neurons” Subacute and chronic neuronal injury – degeneration Axonal reaction – regeneration Neuronal inclusions. Cellular Responses to Injury.

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cellular responses to injury
Cellular Responses to Injury
  • Reactions of neurons to injury
    • Acute neuronal injury – “red neurons”
    • Subacute and chronic neuronal injury – degeneration
    • Axonal reaction – regeneration
    • Neuronal inclusions
cellular responses to injury1
Cellular Responses to Injury
  • Reaction of astrocytes to injury
    • Metabolic buffers and detoxifiers
    • Gliosis
    • Gemistoytic astrocytes
    • Alzheimer type II astrocytes
    • Rosenthal fibers
    • Alexander disease
    • Lafora bodies
cellular responses to injury2
Cellular Responses to Injury
  • Other glial cells – oligodendrocytes and ependyma
    • More limited repertoire of reactions
    • Inclusions
    • CMV – extensive ependymal injury
cellular responses in injury
Cellular Responses in Injury
  • Reactions of microglia to injury
    • Fixed macrophages in the CNS
    • Proliferation
    • Development of elongated nuclei
    • Formation of aggregates about small foci of tissue necrosis ( microglial nodules)
    • Congregation around cell bodies of dying neurons ( neuronophagia)
    • Blood-derived macrophages are principal phagocytic cells in inflammatory foci
cerebral edema hydrocephalus and raised intracranial pressure and herniation
Cerebral Edema, Hydrocephalus, and Raised Intracranial Pressure and Herniation
  • Cerebral Edema
    • Vasogenic edema
    • Cytotoxic edema
    • Hydrocephalic edema
  • Hydrocephalus
    • Accumulation of excessive CSF within the ventricular system
    • Communicating
    • Noncommunicating
    • Hydrocephalus ex vacuo
  • Raised Intracranial pressure and herniation
    • Subfalcine ( cingulate) herniation
    • Transtentorial ( uncinate,mesial temporal) herniation
    • Tonsillar herniation
malformations and developmental diseases
Malformations and Developmental Diseases
  • Neural tube defects
    • Encephalocele
    • Spinal dysraphism ( spina bifida)
    • Myelomeningocele
    • Meningocele
    • Anencephaly
    • Folic acid, alpha-fetoprotein
  • Forebrain anomalies
    • Megaloencephaly or microencephaly
    • Lissencephaly ( agryia)
    • Polymicrogyria

Neuronal heterotopias


Agensis of the corpus callosum

  • Posterior fossa anomalies
    • Dandy-Walker malformation
    • Arnold-Chiari malformation ( Chiari type II),
    • Chiari I malformation
  • Syringomyelia and hydromyelia
perinatal brain injury
Perinatal Brain Injury
  • Brain injury occurring in the perinatal period is an important cause of childhood neurologic disability
  • Cerebral palsy
  • Intraparenchylmal hemorrhage within the germinal matrix
  • Periventricular leukomalacia
  • Multicystic encephalopathy
  • Ulegyria
  • Status marmoratus
  • Skull fractures
  • Parenchymal Injuries
  • Traumatic Vascular Injury
  • Sequelae of brain tumors
  • Spinal cord Trauma – level of lesion determines extent of neurologic manifestation
  • Anatomic location and limited capacity for functional repair – major determinants of consequences of trauma
  • Skull fractures, parenchymal injury, vascular injury or combination
  • Penetrating or blunt (open or closed) injury
  • Displaced skull fracture
  • Basal skull fracture – CSF leak
  • Diastatic
  • Parenchymal Injuries
    • Concussion – clinical syndrome of altered consciousness secondary to head injury typically brought about by a chance in the momentum of the head
      • Instantaneous LOC, temporary respiratory arrest, loss of reflexes, amnesia for the event, post-concussive neuropsychiatric syndromes
  • Direct parenchymal injury
    • Contusion
    • Laceration
    • Coup and contrecoup
    • Plaque jaune
    • Diffuse axonal injury
  • Traumatic vascular injury
    • Epidural hematoma – middle meningeal artery, temporal skull fractures, lucid interval
    • Subdural hematoma – bridging veins, infants and elderly, lysis -> growth of fibroblasts into the hematoma -> early development of hyalinized CT, chronic subdural – multiple episodes of repeat bleding
  • Sequelae of brain trauma
    • Post-traumatic hydrocephalus
    • Post-traumatic dementia
    • Punch-drunk syndrome
    • Post-traumatic epilepsy
    • Meningiomas
    • Infectious diseases
    • Psychiatric disorders
cerebrovascular diseases
Cerebrovascular Diseases
  • Hypoxia, Ischemia, and Infarction
  • Hypertensive cerebrovascular disease
  • Intracranial hemorrhage
cerebrovascular diseases1
Cerebrovascular Diseases
  • Hypoxia, ischemia, and infarction
    • Global cerebral ischemia
      • Hypotension, hypoperfusion, low-flow states
      • Hierarchy of sensitivity to insult
      • Selective vulnerability
      • Border zone “watershed” infarcts
    • Focal cerebral ischemia
      • Adequacy of collateral flow
      • Majority of thrombotic occlusions are due to atherosclerosis
      • Emboli – mural thrombi, MI valvular disease, paradoxical
      • Vasculitis
hypertensive cerebrovascular disease
Hypertensive Cerebrovascular Disease
  • Lacunar infarcts
  • Slit hemorrhages
  • Hypertensive encephalopathy
    • Diffuse cerebral dysfunction
    • Headaches, confusion, vomiting, convulsions, coma
    • Increased intracranial pressure
    • Vascular dementia – Multi-infarct, dementia, gait abnormalities, pseudobulbar signs, superimposed focal defects, Binswanger disease – loss of large areas of white matter
intracranial hemorrhage
Intracranial Hemorrhage
  • Intracerebral (intraparenchymal)
    • Hypertension is the most common underlying cause of primary brain parenchymal hemorrhage
    • Cerebral amyloid angiopathy
    • Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy
intracranial hemorrhage1
Intracranial Hemorrhage
  • Subarachnoid hemorrhage
    • Saccular (berry) aneurysm – most frequent cause, Table 28-19 – common sites, sporadic most common, also AD polycystic kidney disease, Ehlers-Danlos, type IV, NF type 1, Marfan), “Worst headache of my life”
intracranial hemorrhage2
Intracranial Hemorrhage
  • Vascular malformations
    • Arteriovenous malformation
    • Cavernous malformation
    • Capillary telangiectasias
    • Venous angiomas
  • Acute meningitis
  • Acute focal suppurative infections
  • Chronic bacterial meningoencephalitis
  • Viral meningoencephalitis
  • Fungal Meningoencephalitis
  • Other infectious diseases of the nervous system
principal routes of spread of microorganisms into the cns
Principal routes of spread of microorganisms into the CNS

Hematogenous spread

Direct implantation

Local extension

Transport along the peripheral NS


Inflammatory process of the leptomeninges and CSF within the subarachnoid space

Acute pyogenic (bacterial)

Purulent CSF, exudate within the leptomeninges, pus tracts along blood vessels

Aseptic (viral)

less fulminant

Chronic (TB, syphilis, cryptococcal, lyme disease

acute focal suppurative infections
Acute Focal Suppurative Infections
  • Brain abscess
    • Acute bacterial endocarditis, congenital heart disease, chronic pulmonary sepsis, immunosuppression
  • Subdural empyema
  • Extradural abscess
viral meningoencephalitis
Viral Meningoencephalitis
  • Arthropod-borne – West Nile
  • Herpes simplex type 1 and type 2
  • Herpes Zoster
  • CMV
  • Poliomyelitis – anterior horn cells
  • Rabies – Negri bodies
  • HIV
  • Progressive multifocal leukoencephalopathy – JC polyomavirus
  • Subacutesclerosingpanencephalitis - measles
fungal meningoencephalitis
Fungal Meningoencephalitis
  • Candida, Mucor, Aspergillus, Crytococcus
  • Chronic meningitis
  • Vasculitits
  • Parenchymal invasion
  • Cerebral amebiasis fatal necrotizing encephalitis or chronic
  • Toxoplasmosis
    • Opportunistic
    • Immunosuppression or maternal infection
    • Multiple ring-enhancing lesions
transmissible spongiform encephalopathies prion diseases
Transmissible Spongiform Encephalopathies (Prion diseases)
  • Creutzfeldt-Jacob disease
  • Gerstmann-Straussler-Scheinker syndrome
  • Fatal familial insomnia
  • Kuru
  • Figure 28-31
demyelinating diseases
Demyelinating Diseases
  • Multiple sclerosis
  • Neuromyelitisoptica – Devic disease
    • Bilateral optic neuritis and spinal cord demyelination
  • Acute disseminated encephalomyelitis and acute necrotizing hemorrhagic encephalomyelitis
  • Other diseases with demyelination
    • Central pontinemyelinolysis – rapid correction of hypomatremia
multiple sclerosis
Multiple Sclerosis
  • Autoimmune demyelinating disorder characterized by distinct episodes of neurologic deficits, separated in time, attributable to white matter lesions that are separated in space
  • Immune response against components of the myelin sheat
  • Plaques – active, inactive, shadow
  • Visual impairment, cranial nerve signs, ataxia, nystagmus, spinal cord lesions,
  • CSF – elevated protein, 1/3 pleocytosis, increased IgG
degenerative diseases
Degenerative Diseases
  • Degenerative diseases affecting the cerebral cortex
  • Degenerative diseases of basal ganglia and brainstem
  • Spinocerebellar degenerations
  • Degenerative diseases affecting the motor neuron
degenerative diseases affecting the cerebral cortex
Degenerative Diseases affecting the Cerebral cortex
  • Alzheimer disease
    • Most common cause of dementia in the elderly
    • Most cases are sporadic, 10% familial
    • Cortical arophy
    • Neuritic plaques
    • Neurofibrillary tangles
    • Abeta peptides
    • Abnormal forms of protein tau
    • Neuropil threads
    • CAA
  • Frontotemporal dementias
    • Frontotemproal dementia with parkinsonisn linked to Tau mutations
    • Pick disease
    • Progressive supranuclear palsy
    • Corticobasaldegneration
    • Frontotemporal dementias withou tau pathology
  • Vascular dementia
degenerative diseases of basal g anglia and brainstem
Degenerative Diseases of Basal Ganglia and Brainstem
  • Parkinsonism – diminished facial expression, stooped posture, slowness of voluntary movements, festinating gait, rigidity, “pill-rolling” tremor
  • Parkinson disease – dopamine, pallor of substantianigra, alpha-synuclein mutations, lewy bodies
  • Dementia with Lewy bodies
  • Multiple system atrophy – inclusions in oligodendrocytes
  • Huntington disease – progressive movement disorders, dementia, degeneration of striatal nuerons, atrophy of caudate nucleus,
spinocerebellar degeneraitons
  • Spinocerebellar ataxia
    • Friedreich ataxia – frataxin mutations, GAA trinucleotide-repeat, cardiomyopathy
    • Ataxia-telangiectasia - immunodeficeincy
degenerative diseases affecting motor neurons
Degenerative diseases affecting Motor Neurons
  • Amyotrophic lateral sclerosis – lower motor and upper motor neurons
  • Bulbospinal atrophy ( Kennedy syndrome)
  • Spinal muscle atrophy
genetic metabolic diseases
Genetic Metabolic Diseases
  • Neuronal Storage diseases
    • Neuronal ceroidlipofuscinoses
    • Tay-Sachs disease
  • Leukodystrophies
    • Krabbe disease - deficiency of galatocerebroside beta-galactosidase
    • Metachromicleukodystrophy – deficiency of lysosomal enzyme arylsulfatase
    • Adrenoleukosystrophy
    • Pelizaeus-Merzbacher disease
    • Canavan disease
    • Alexander disease
    • Vanisning-white-matter leukodystrophy
  • Mitochondrial encephalomyopathies
    • Mitochondrial encephalopathy, lactic acidosis, strokelike episodes (MELAS)
    • Myoclonic epilepsy and ragged red fibers (MERRF)
    • Leigh syndorme (subacute necrotizing encephalopathy
    • Kearn-Sayre syndrome
    • Alpers disease
toxic and acquired metabolic diseases
Toxic and Acquired Metabolic Diseases
  • Vitamin deficiencies
    • Vitamin B12
    • Thiamine (B1)
      • Beriberi, Wenicke encephalopathy and Korsakoff syndrome
  • Neurologic sequelae of metabolic disturbances
    • Hypoglycemia
    • Hyperglycemia
    • Hepatic encephalopathy
  • Toxic disorders
    • Carbon monoxide
    • Methanol
    • Ethanol
    • Radiation
    • Combined radiation and methotrexate induced injury
  • Gliomas
  • Neuronal tumors
  • Poorly differentiated neoplasms
  • Other parenchymal tumors
  • Meningiomas
  • Paraneoplastic syndromes
  • Peripheral nerve sheath tumors
  • Familial tumor syndromes

20% of all childhood cancers are CNS tumors

70% of childhood tumors arise in the posterior fossa

70% of adult tumors arise in cerebral hemispheres, supratentorial

Rarely metastasize outside of the CNS

Symptoms – seizures, headaches, focal neurological deficits, hydrocephalus, ataxia



Infiltrating vs non-infiltrating (pilocytic)

Grade I – pilocytic – often cystic

Grade II – diffuse astrocytoma

Grade III – anaplastic astrocytoma

Grade IV – glioblastoma (pseudopalisading)


White matter

Well-circumscribed, better prognosis


NF2, ependyma-lined ventricular system

Perivascular pseudorosettes


Choroid plexus papillomas/ carcinomas

Colloid Cyst of third ventricle


Poorly differentiated


Midline of the cerebellum

Desmoplastic variant

Drop metastases – cauda equina


Attached to the dura

Usually benign

En plaque

Psammoma bodies




¼ to ½ of intra-cranial tumors in hospitalized patients

Five most common






peripheral nerve sheath tumors
Peripheral Nerve Sheath Tumors


Neural crest-derived Schwann cell

Acoustic neuroma – actually vestibular



Peripheral nerve – solitary or plexiform

Malignant peripheral sheath tumors

familial tumor syndromes
Familial Tumor Syndromes

Neurofibromatosis Type I – AD, Lisch nodules, café au lait spots

Neurofibromatosis Type II – AD, 8th nerve schannomas and multiple meningiomas

Tuberous Sclerosis – AD, hamartomas ( cortical tubers) and benign neoplasms of the brain; seizures; liver, kidney, pancreas cysts; angifibromas, shagreen patches, ash-leaf spots, subungal fibromas

Von Hippel – Lindau Disease – AD, hemangioblastomas

(cerebellum and retina); cysts of liver, pancreas, kidney; renal cell carcinoma, pheochromocytomas