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Chapter 17 ( CNS ) Flashcards

1
Q

Neural tube components differentiate into ?

A

The wall : CNS
The hollow lumen : the ventricles and spinal cord canal
The neural crest : PNS

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2
Q

Cause of neural tube defects ?

A

Low folate levels prior to conception

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3
Q

Diagnosis of neural tube defect during prenatal care is made by ?

A

Elevated AFP levels in the amniotic fluid and maternal blood

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4
Q

Anencephaly is associated with ?

A

Maternal polyhydramnios

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5
Q

Spina bifida mechanism ? Presentation ?

A

Failure of the posterior vertebral arch to close resulting in a vertebral defect

Presents as :
1- dimple or patch of hair overlying the vertebral defect
2- cystic protrusion of the underlying tissue through the vertebral defect : meningocele or meningomyelocele

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6
Q

CSF circulation ?

A

Produced by choroid plexus lining the ventricles
Flow from lateral to 3rd ventricle through interventricular foramen of Monro
Flow from 3rd to 4th ventricle through the cerebral aqueduct
Flow from 4th to the subarachnoid space through foramina of Magendie and Luschka

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7
Q

Dandy Walker malformation mechanism ? Presentation ?

A

Congenital failure of the cerebellar vermis to develop which separates the 2 sides of cerebellum

Presents with :
Massively dilated 4th ventricle ( posterior fossa )
An absent cerebellum
Hydrocephalus

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8
Q

Arnold Chiari malformation type ll mechanism ? Associations ?

A

Congenital downward displacement of cerebellar vermis and tonsils through the foramen magnum

Associated with :
Hydrocephalus
Meningomyelocele
Syrigomyelia

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9
Q

Syringomyelia mechanism ? Causes ? Site ? Presentation ?

A

Cystic degeneration of the spinal cord

In association with trauma or Arnold Chiari malformation

C8-T1

Presentation :
Degeneration of anterior white commissure with sparing of dorsal column
Syrinx expansion may involve lower motor neurons of the anterior horn or lateral horn of the hypothalamospinal tract

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10
Q

Sympathetic input to the face is carried by ?

A

Lateral horn of the hypothalamospinal tract

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11
Q

Poliomyelitis mechanism ?

A

Damage of the anterior motor horn due to poliovirus infection

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12
Q

Werding-Hoffman disease mechanism ? Mode of inheritance ? Presentation ?

A

Inherited degeneration of anterior motor horn

Autosomal recessive

Presents as a Floppy baby ( death occurs within a few years after birth

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13
Q

Amyotrophic lateral sclerosis mechanism ? Associated with which mutation ?

A

Degenerative disorder of upper and lower motor neurons of the corticospinal tract
Anterior motor horn degeneration leads to lower motor neuron lesion
Lateral corticospinal tract degeneration leads to upper motor neuron lesion

Zinc-copper superoxide dismutase mutation (SOD1) is present in some familial cases leads to free radical injury in the neurons

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14
Q

ALS is distinguished from syringomyelia by ?

A

Lack of sensory impairment

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15
Q

Friedriech ataxia mechanism ? Presentation ? Associated with ?

A

Degenerative disorder of the cerebellum and spinal cord
Autosomal recessive
Due to trinuleotide repeat expansion ( GAA ) in the Frataxin gene

Presents in childhood , patients are wheelchair bound within a few years

Associated with Hypertrophic cardiomyopathy

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16
Q

Frataxin gene function ? Loss results in ?

A

Essential for mitochondrial iron regulation

Loss of which leads to iron build up with free radicle damage

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17
Q

Leptomeninges ?

A

Pia and Arachnoid

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18
Q

Causes of meningitis ?

A

1- group B streptococci , E coli and listeria monocytogenes ( in neonates )
2- N meningitidis ( children and teenagers )
Streptococcus pneumoniae ( adults and elderly )
H influenza ( nonvaccinated infants )
3- Coxsackievirus ( children by feco oral transmission )
4- Fungi ( immunocompromised individuals )

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19
Q

Site of lumber puncture ? Layers crossed ?

A

Between L4 and L5 ( level of iliac crest )

Skin
Ligaments 
Epidural space 
Dura
Arachnoid
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20
Q

CSF findings in meningitis ?

A

1- Bacterial meningitis : neutrophils with ⬇️ CSF glucose , gram stain and culture identify the causative organism
2- Viral meningitis : Lymphocytes with normal CSF glucose
3- Fungal meningitis : Lymphocytes with ⬇️ CSF glucose

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21
Q

Complications of meningitis ?

A

Death ( herniation due to cerebral edema )

Hydrocephalus , hearing loss and seizures ( sequelae related to fibrosis )

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22
Q

Neurons undergo necrosis in how much time of ischemia ?

A

3-5 mins

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23
Q

Clinical features of global cerebral ischemia ?

A

1- Mild : transient confusion with prompt recovery ( as in insulinoma )
2- Severe : results in diffuse necrosis , survival leads to a Vegetative state
3- Moderate : leads to infarcts of watershed areas and damage to highly vulnerable regions such as :
Pyramidal neurons of cerebral cortex (layers 3,5,6) leads to laminar necrosis
Pyramidal neurons of the hippocampus
Purkinje layer of the cerebellum ( integrates sensory perception with motor control )

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24
Q

Watershed areas of the brain ?

A

Area lying between regions fed by the anterior and middle cerebral artery

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25
Common sites of atherosclerosis in the brain ?
Bifurcation of internal carotid | Bifurcation of middle cerebral artery in circle of Willis
26
Thrombotic stroke results in ?
Pale infarcts at the periphery of the cortex
27
Embolic stroke usually involves ? Results in ?
The middle cerebral artery Hemorrhagic infarct at the periphery of the cortex
28
Lacunar stroke cause ? Involves what ?
Hyaline arteriolosclerosis which is a complication of hypertension Involves: Lenticulostriate vessels ( most commonly ): results in small cystic areas of infarction The internal capsule : results in pure motor stroke The thalamus : results in pure sensory stroke
29
Histological changes in ischemic stroke ?
Liquefactive necrosis : 1- 12 h after infarction —>Red neurons ( eosinophilic changes in the cytoplasm of neurons ) 2- 24 h —> Necrosis 3- 1-3 days —> Neutrophils 4- 4-7 days —> Microglial cells 5- 2-3 weeks —> Gliosis 6- net result —> fluid filled cystic space surrounded by gliosis
30
Cause of intracerebral hemorrhage ?
Due to rupture of Charcot-Bouchard microaneurysms of the lenticulostriate vessels which is a complication of hypertension and occurs most commonly in the basal ganglia
31
In subarachnoid hemorrhage lumbar puncture shows ?
Xanthochromia ( yellow hue due to bilirubin break down )
32
Causes of subarachnoid hemorrhage ?
Rupture of Berry aneurysm 85% AV malformation Anticoagulant state
33
Berry aneurysm gross and micro ? Location ? Associated with ?
Thin walled saccular outpouching Lack a media layer Most frequently in the anterior circle of Willis at branch points of the anterior communicating artery Associated with Marfan syndrome and ADPCK
34
Cause of Epidural hematoma ?
Due to fracture of the temporal bone with rupture of the middle meningeal artery resulting in lens shaped hematoma on CT
35
Cause of subdural hematoma ?
Due to tear of the bridging veins between the dura and arachnoid usually arises with trauma resulting in crescent shaped hematoma on CT
36
Causes of increased rate of occurrence of subdural hematoma in the elderly ?
Because of cerebral atrophy which exerts stretch on the veins
37
Types of brain herniation ? Cause ? Consequences ?
1- tonsillar herniation : the cerebellar tonsils herniates through the foramen magnum Compression of the brain stem leads to cardiopulmonary arrest 2-subfalcine herniation : the cingulate gyrus herniates under the falx cerebri Compression of the anterior cerebral artery leads to infarction 3- uncal herniation : the temporal lobe uncus herniates under the tentorium cerebelli Compression of CN lll leads to eye movements down and out and a dilated pupil Compression of posterior cerebral artery leads to infraction of occipital lobe -> contralateral homonymous hemianopsia Rupture of the paramedian artery leads to Duret hemorrhage
38
Which cells myelinate the CNS ?
Oligodendrocytes
39
Which cells myelinate the PNS ?
Schwann cells
40
Most common cause of leukodystrophies ?
Metachromatic leukodystrophy
41
Metachromatic leukodystrophy mechanism ?
Autosomal recessive Due to deficiency of Arylsulfatase —> Sulfatides cannot be degraded and accumulate in the lysosomes of oligodendrocytes ( lysosomal storage disease )
42
Krabbe disease mechanism ?
Autosomal recessive | Due to deficiency of Galactocerebrosidase ( beta-galactosidase ) —> Glactocerebrosides accumulates in macrophages
43
Adrenoleukodystrophy mechanism ?
X linked defect Due to impaired addition of CoA to long chain fatty acids —> Fatty acids accumulates which damages the adrenal gland and white matter of the brain
44
Multiple sclerosis mechanism ? Presents in ? Associated with ?
Autoimmune destruction of CNS myeline and oligodendrocytes Most common chronic CNS disease of young adults (20-30) more common in women most commonly seen in regions away from the equator Associated with HLA-DR2
45
Multiple sclerosis diagnosis ? Gross ? Ttt ?
MRI : plaques ( areas of white matter demyelination ) Lumbar puncture : Increased lymphocytes Myelin basic protein Increased immunoglobulins with oligoclonal IgG bands on high resolution electrophoresis Gross : gray appearing plaques on the white matter Ttt : high dose steroids in acute attacks and long term ttt with Interferon beta
46
Subacute sclerosing panencephalitis cause ? Presentation ? Histology ?
Slowly progressing persistent infection of the brain with Measles virus Infection occurs in infancy but neurological signs arise years later during childhood Histo : viral inclusions within neurons ( grey matter ) and oligodendrocytes ( white matter )
47
Progressive multifocal leukoencephalopathy mechanism ? Presentation ?
JC virus infection of oligodendrocytes ( white matter ) , immunosuppression leads to reactivation of the latent virus Presents with rapidly progressive neurological signs leading to death
48
Central pontine myelinolysis mechanism ? Occurs in ? Presentation ?
Focal demyelination of the pons due to rapid intravenous correction of hyponatremia Occurs in severely malnourished patients Presents as acute bilateral paralysis except the eyes which can move ( Locked in syndrome )
49
Most common cause of death in Alzheimer disease ?
Infection ( as the patients eventually become bedridden and mute )
50
Increased risk for sporadic Alzheimer disease is seen with ? An decreased with ?
Increased with Epsilon4 allele of apolipoprotein E (APOE) Decreased with Epsilon2 allele of APOE
51
Early onset Alzheimer disease is seen in ?
Familial cases with Presenilin 1 and Presenilin 2 mutations Down syndrome because they have 3 copies of APP gene which is present on chromosome 21
52
Morphologic features of Alzheimer disease ?
1- Cerebral atrophy 2- Neuritic plaques : extracellular core comprised of A beta amyloid with entangled neuritic processes 3- Neurofibrillary tangles : intracellular aggregate of fibers composed of hyperphosphorylated Tau protein 4- loss of cholinergic neurons in the nucleus basalis of Meynert
53
Ventricular dilatation secondary to cerebral atrophy ?
Hydrocephalus ex vocuo
54
Diagnosis of Alzheimer disease is confirmed by ?
Histology at autopsy
55
The second most common cause of dementia ?
Vascular dementia due to multiple infarctions and injury caused by Hypertension Atherosclerosis Vasculitis
56
Pick disease mechanism ? Histology ? Presentation ?
Degenerative disease of frontal and temporal cortex Round aggregates of Tau proteins ( Pick bodies ) in the neurons of the cortex Presents early with behavioral and language symptoms Presents eventually with dementia
57
Historically rare cases of Parkinson’s disease were related to ?
MPTP exposure ( a contaminant in illicit drugs ?
58
Parkinson’s disease histology ?
Loss of pigmented neurons in substantia nigra | Round eosinophilic inclusions of alpha-synuclein ( Lewy bodies ) in affected neurons
59
Early onset dementia in Parkinson’s disease is suggestive of ? Characterized by ? Histology ?
Lewy body dementia Dementia Hallucinations Parkinson’s Histology : Cortical Lewy bodies
60
Huntington disease mechanism ?
Degeneration of GABAergic neurons in the caudate nucleus of the basal ganglia Autosomal dominant disorder Chromosome 4 Trinucleotide expansion CAG in the huntingtin gene Further expansion of CAG repeats during spermatogenesis leads to ANTICIPATION
61
Common cause of death in Huntington disease ?
Suicide
62
Normal pressure hydrocephalus presentation ? Ttt ?
Traid of : wet wobbly wacky Urinary incontinence Gait instability Dementia Ttt : Lumbar puncture improve symptoms Ventriculoperitoneal shunting
63
Spongiform encephalopathy mechanism ? Histology ?
Degenerative disease due to conversion of Prion protein to a Beta pleated conformation which can be : Sporadic Inherited Transmitted Pathologic protein PrPsc is not degradable and converts normal protein PrPc into pathologic form PrPsc resulting in a viscous circle This pathologic protein PrPsc causes damage to neurons and glial cells Histology : intracellular vacuoles ( spongy degeneration )
64
Most common spongiform encephalopathy ? Mechanism ? Presentation ?
Creutzfeldt-Jakob disease (CJD) Usually sporadic Can arise due to exposure to prion infected human tissue as : Human growth hormone Corneal transplant Presents as : Rapidly progressive dementia ( within weeks or months ) Ataxia Startle myoclonus Periodic sharp waves ( spike complexes ) on EEG
65
Cause of variant CJD ?
Exposure to bovine spongiform encephalopathy
66
Familia fatal insomnia mechanism ? Characterized by ?
Inherited form of prion disease Characterized by : Severe insomnia Exaggerated startle response
67
Characters of CNS metastatic tumors ?
Multiple well circumscribed lesions at the grey white junction
68
Most common CNS tumors in adults ?
Gluoblastoma multiforme Meningioma Schwannoma
69
Most common tumors in children ?
Pilocytic astrocytoma Ependymoma Medulloblastoma
70
Most common primary CNS tumor in adults ?
Glioblastoma multiforme
71
Glioblastoma multiforme arises from ? Site ? Histology ?
Astrocytes Inthe cerebral hemisphere crossing the corpus callosum ( butterfly lesion ) Histo : regions of necrosis surrounded by tumor cells ( pseudopallisading ) and endothelial cell proliferation Tumor cells are GFAP positive
72
Meningioma arises from ? Presentation ? Imaging ? Histology ?
Arachnoid cells Seizures ( tumor compresses but does not invade the cortex ) Imaging : a round mass attached to the dura Histology : a whorled pattern with psammoma bodies
73
Most common benign CNS tumor in adults ?
Meningioma
74
Schwannoma arises from ? Site ? Bilateral tumors are seen in ? Tumor cells characterized by ?
Schwann cells Cranial or spinal nerves , most commonly CN lll at the cerebellipontine angle ( loss of hearing and tinnitus ) Bilateral in neurofibromatosis type ll Tumor cells are S-100 positive
75
Oligodendroglioma arises from ? Imaging ? Presentation ? Histology ?
Oligodendrocytes MALIGNANT Calcified tumor in the white matter involving the frontal lobe Seizures Histo : fried egg appearance of cells
76
Most common CNS tumor in children ?
Pilocytic astrocytoma
77
Pilocytic astrocytoma arises from ? Site ? Imaging ? Histology ?
Astrocytes Cerebellum Imaging : cystic lesion with a mural nodule Histo : Rosenthal fibers ( thick eosinophilic processes of astrocytes ) and eosinophilic granular bodies Tumor cells are GFAP positive
78
Medulloblastoma arises from ? Histology ? Prognosis ?
The granular cells of cerebellum ( neuroectoderm ) Histo : small round blue cells Homer-Wright rosettes may be present Poor prognosis , tumor grows rapidly and spreads via CSF
79
Medulloblastoma spread to the cauda equina ?
Drop metastasis
80
Ependymoma arises from ? Site ? Presentation ? Histology ?
Ependymal cells The 4th ventricle Hydrocephalus Histo : Perivascular pseudorossets
81
Craniopharyngioma arises from ? Site ? Presentation ? Imaging ?
Epithelial remnants of Ranthke’s pouch A supratentorial mass Bitemporal hemianopia ( due to compression of optic chiasma ) Imaging : calcification Benign but tend to recur after resection

Pathology (18 decks)

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