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Pathology > Chapter 17 ( CNS ) > Flashcards

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
Q

Common sites of atherosclerosis in the brain ?

A

Bifurcation of internal carotid

Bifurcation of middle cerebral artery in circle of Willis

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26
Q

Thrombotic stroke results in ?

A

Pale infarcts at the periphery of the cortex

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27
Q

Embolic stroke usually involves ? Results in ?

A

The middle cerebral artery

Hemorrhagic infarct at the periphery of the cortex

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28
Q

Lacunar stroke cause ? Involves what ?

A

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

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29
Q

Histological changes in ischemic stroke ?

A

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

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30
Q

Cause of intracerebral hemorrhage ?

A

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

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31
Q

In subarachnoid hemorrhage lumbar puncture shows ?

A

Xanthochromia ( yellow hue due to bilirubin break down )

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32
Q

Causes of subarachnoid hemorrhage ?

A

Rupture of Berry aneurysm 85%
AV malformation
Anticoagulant state

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33
Q

Berry aneurysm gross and micro ? Location ? Associated with ?

A

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
Q

Cause of Epidural hematoma ?

A

Due to fracture of the temporal bone with rupture of the middle meningeal artery resulting in lens shaped hematoma on CT

35
Q

Cause of subdural hematoma ?

A

Due to tear of the bridging veins between the dura and arachnoid usually arises with trauma
resulting in crescent shaped hematoma on CT

36
Q

Causes of increased rate of occurrence of subdural hematoma in the elderly ?

A

Because of cerebral atrophy which exerts stretch on the veins

37
Q

Types of brain herniation ? Cause ? Consequences ?

A

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
Q

Which cells myelinate the CNS ?

A

Oligodendrocytes

39
Q

Which cells myelinate the PNS ?

A

Schwann cells

40
Q

Most common cause of leukodystrophies ?

A

Metachromatic leukodystrophy

41
Q

Metachromatic leukodystrophy mechanism ?

A

Autosomal recessive
Due to deficiency of Arylsulfatase —> Sulfatides cannot be degraded and accumulate in the lysosomes of oligodendrocytes ( lysosomal storage disease )

42
Q

Krabbe disease mechanism ?

A

Autosomal recessive

Due to deficiency of Galactocerebrosidase ( beta-galactosidase ) —> Glactocerebrosides accumulates in macrophages

43
Q

Adrenoleukodystrophy mechanism ?

A

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
Q

Multiple sclerosis mechanism ? Presents in ? Associated with ?

A

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
Q

Multiple sclerosis diagnosis ? Gross ? Ttt ?

A

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
Q

Subacute sclerosing panencephalitis cause ? Presentation ? Histology ?

A

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
Q

Progressive multifocal leukoencephalopathy mechanism ? Presentation ?

A

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
Q

Central pontine myelinolysis mechanism ? Occurs in ? Presentation ?

A

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
Q

Most common cause of death in Alzheimer disease ?

A

Infection ( as the patients eventually become bedridden and mute )

50
Q

Increased risk for sporadic Alzheimer disease is seen with ? An decreased with ?

A

Increased with Epsilon4 allele of apolipoprotein E (APOE)

Decreased with Epsilon2 allele of APOE

51
Q

Early onset Alzheimer disease is seen in ?

A

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
Q

Morphologic features of Alzheimer disease ?

A

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
Q

Ventricular dilatation secondary to cerebral atrophy ?

A

Hydrocephalus ex vocuo

54
Q

Diagnosis of Alzheimer disease is confirmed by ?

A

Histology at autopsy

55
Q

The second most common cause of dementia ?

A

Vascular dementia due to multiple infarctions and injury caused by
Hypertension
Atherosclerosis
Vasculitis

56
Q

Pick disease mechanism ? Histology ? Presentation ?

A

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
Q

Historically rare cases of Parkinson’s disease were related to ?

A

MPTP exposure ( a contaminant in illicit drugs ?

58
Q

Parkinson’s disease histology ?

A

Loss of pigmented neurons in substantia nigra

Round eosinophilic inclusions of alpha-synuclein ( Lewy bodies ) in affected neurons

59
Q

Early onset dementia in Parkinson’s disease is suggestive of ? Characterized by ? Histology ?

A

Lewy body dementia

Dementia
Hallucinations
Parkinson’s

Histology : Cortical Lewy bodies

60
Q

Huntington disease mechanism ?

A

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
Q

Common cause of death in Huntington disease ?

A

Suicide

62
Q

Normal pressure hydrocephalus presentation ? Ttt ?

A

Traid of : wet wobbly wacky
Urinary incontinence
Gait instability
Dementia

Ttt :
Lumbar puncture improve symptoms
Ventriculoperitoneal shunting

63
Q

Spongiform encephalopathy mechanism ? Histology ?

A

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
Q

Most common spongiform encephalopathy ? Mechanism ? Presentation ?

A

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
Q

Cause of variant CJD ?

A

Exposure to bovine spongiform encephalopathy

66
Q

Familia fatal insomnia mechanism ? Characterized by ?

A

Inherited form of prion disease

Characterized by :
Severe insomnia
Exaggerated startle response

67
Q

Characters of CNS metastatic tumors ?

A

Multiple well circumscribed lesions at the grey white junction

68
Q

Most common CNS tumors in adults ?

A

Gluoblastoma multiforme
Meningioma
Schwannoma

69
Q

Most common tumors in children ?

A

Pilocytic astrocytoma
Ependymoma
Medulloblastoma

70
Q

Most common primary CNS tumor in adults ?

A

Glioblastoma multiforme

71
Q

Glioblastoma multiforme arises from ? Site ? Histology ?

A

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
Q

Meningioma arises from ? Presentation ? Imaging ? Histology ?

A

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
Q

Most common benign CNS tumor in adults ?

A

Meningioma

74
Q

Schwannoma arises from ? Site ? Bilateral tumors are seen in ? Tumor cells characterized by ?

A

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
Q

Oligodendroglioma arises from ? Imaging ? Presentation ? Histology ?

A

Oligodendrocytes MALIGNANT

Calcified tumor in the white matter involving the frontal lobe

Seizures

Histo : fried egg appearance of cells

76
Q

Most common CNS tumor in children ?

A

Pilocytic astrocytoma

77
Q

Pilocytic astrocytoma arises from ? Site ? Imaging ? Histology ?

A

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
Q

Medulloblastoma arises from ? Histology ? Prognosis ?

A

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
Q

Medulloblastoma spread to the cauda equina ?

A

Drop metastasis

80
Q

Ependymoma arises from ? Site ? Presentation ? Histology ?

A

Ependymal cells

The 4th ventricle

Hydrocephalus

Histo : Perivascular pseudorossets

81
Q

Craniopharyngioma arises from ? Site ? Presentation ? Imaging ?

A

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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