USMLE: step 1 > CNS > Flashcards

CNS Flashcards

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1
Q

Cause of neural tube defects?

A

Low folate prior to conception

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2
Q

What is elevated AFP seen in ?

A

Neural tube defects

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3
Q

What does failure of posterior vertebral arch cause?

A

Spina bifida

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4
Q

Foramen of monro?

A

CSF from lateral to third ventricle

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5
Q

Cerebral aqueduct?

A

Drains 3rd - 4th ventricle

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6
Q

Presentation of aqueduct stenosis?

A

Enlarging head circumference in infant

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7
Q

Dandy walker?

A
  • Failed cerebellar vermis
  • Dilated 4th
  • Absent cerebellum
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8
Q

Arnold chiari?

A

Cerebellar tonsils through foramen magnum
Type 1: asymptomatic
Type 2: obstructed CSF flow

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9
Q

Cause of syringomyelia?

A

Cystic degeneration of spinal cord from:

  1. Trauma
  2. Arnold chiari
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10
Q

Where does syringomyelia usually occur?

A

C8 - T1

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11
Q

Presentation of syringomyelia?

A
  1. Loss of pain and temp
  2. Intact proprioception
  3. LMN signs in expands to lower motor horn
  4. Horner’s if lateral horn knocked out
    * **STT knocked out as this crosses in center where syrinx is DCP is preserved as syrinx is not hitting dorsal spinal cord
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12
Q

What occurs is syrinx knocks out lateral horn?

A

Horner’s

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13
Q

Polio?

A

Anterior motor horn damage = LMN signs

  1. Atrophy
  2. Weakness
  3. Flaccid paralysis
  4. Imparied reflexes
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14
Q

What is werdnig hoffman?

A

“Floppy baby syndrome”

Inherited degeneration of anterior motor horn: presents just like polio buy in baby

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15
Q

What is ALS?

A
  • ## Degenerative UMN and LMN (think ALS is hitting “all the motor horns”)
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16
Q

Destruction of what causes UMN and LMN signs?

A

LMN: anterior motor horn
UMN: lateral corticospinal tract

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17
Q

What is atrophy / weakness of hands early sign of?

A

ALS

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18
Q

How to tell ALS form syringomyelia?

A

In ALS, there is not loss of pain and temperature sensation

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19
Q

Cause of familial ALS?

A

Zinc-copper superoxide dismutase mutation

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20
Q

What is SOD?

A

“Superoxide dismutase”

  • Converts Oxide to hydrogen peroxide to prevent free radical damage
  • Loss of enzyme implicated in familial cases of ALS
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21
Q

What is friedreich ataxia?

A
  • Degeneration of spinal cord and cerebellum:
    1. Ataxia: cerebellar
    2. Vibratory / proprioceptive loss
    3. Lower extremity weakness
    4. Absent DTRs
    5. HOCM
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22
Q

Cause of freidrichs?

A

AR: GAA repeat in frataxin gene

- Responsible for iron regulation if out of order leads to ROS via fenton rxn

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23
Q

What are the leptomeninges?

A

“Light meninges”

- Pia and arachnoid that surround brain - what is inflamed in meningitis

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24
Q

Meningitis in non vaccinated infant?

A

H flu

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25
Viral meningitis?
Coxsackie
26
Meningitis presentation?
1. Headache 2. Neck stiffness 3. Fever 4. Vomit 5. Photophobia
27
Where is lumbar puncture?
L4-5: iliac crest - Cord ends at L2 and we dont want to hit this - Trying to hit subarachnoid that continues lower
28
What does LP go through?
``` Skin Ligaments Epidural Dura Arachnoid ***DO NOT pierce pia ```
29
LP fluid diagnosis?
Bact: Neuts, low glucose Viral: Lymph, normal glucose Fungal: Lymphocytes, low glucose
30
CV ischemia or hemorrhage more common?
Ischemia
31
Mild global ischemia?
Transient confusion with complete recovery: seen in insulinoma dropping brain sugar
32
Severe global ischemia?
- Brain necrosis from ischemia - death or coma
33
What does moderate global ischemia cause?
Watershed infarct
34
What are pyramidal neurons?
- Layers 3/5/6 of cortex | - Highly vulnerable to ischemia "cortical laminar necrosis"
35
Areas vulnerable to moderate global?
1. Pyramid 3/5/6 "cortical laminar necrosis" 2. Pyramid of hippocampus 3. Cerebellar purkinjes
36
Difference in transient ischemic attack and stroke?
TIA:
37
Cuase of pale and hemorrhagic infarct in stroke?
Pale: thrombosis Hemorrhagic: embolism
38
Most common source of embolic stroke?
Afib LA: to MCA
39
What is lacunar stroke?
- Hyaline arteriolosclerosis in small vessels of brain | - Most often in lenticulostriate vesicles feeding deep structures of brain
40
Microscopic progress of ischemic stroke?
Liquefactive necrosis in following steps: 1. Red neurons: 12 -24 hours 2. Neuts / microglia / granulation tissue (week) 3. Fluid cyst surrounded by gliosis (Month)
41
What is gliosis?
Reactive astrocytes lining cystic space
42
What are microglials?
Macs in brain
43
Common cause of intracerebral hemorrhage?
- Rupter of charcot bouchard microaneurysm from HTN - Usually impact basal ganglia - Also are occurring in lenticulate from atherosclerosis weakening walls
44
Most common area impacted by charcot bouchard microaneurysm?
Basal ganglia
45
Worst headache with xanthochromia on LP?
Subarachnoid | - Usually from berry in anterior willis at branch of anterior communicating artery
46
What does Berry lack?
Medial layer
47
2 berry aneurysm associations?
1. Marfan's | 2. ADPKD
48
What is epidural hematoma?
- Collection of blood on top of dura - From temporal bone fracture and rupture of MMA - High pressure surface so bleeds fast - Lense shaped lesion
49
What is talk and die syndrome?
Epidural hematoma | - Herniation of the hematoma causing this as the artery a is a high pressure circuit
50
Tonsillar herniation?
- Cerebellar tonsils through magnum compressing brain stem | * Cardiopulmonary arrest
51
Subfalcine herniation?
Cingulate gyrus herniates under falx cerebri (butt crack of brain) compressing ACA
52
Uncal herniation?
Uncus of temporal lobe between cerebellum and brainstem causing: 1. CN 3 compression: down and out with dilated pupil 2. PCA compression: occipital infarct 3. Pull on marmedian a.: brainstem hemorrhage
53
What happens if CN3 compressed?
Down and out dilated pupil
54
What myelinates axons?
CNS: oligodendrocytes PNS: Schwann
55
What happens in demyelinating disorders?
- Preserved axons with destruction of oligos or myelin | - Conduction velocity is greatly impaired
56
What is leukodystrophy?
- Impairment of enzymes necessary to make myelin
57
What is metachromatic leukodystrophy?
- Arylsulfatase deficiency: cannot degrade myelin so it accumulates in lysosomes
58
What is following: | Arylsulfatase deficiency: cannot degrade myelin so it accumulates in lysosomes
Metachromatic leukodystrophy
59
Krabbe disease?
Galactocerebrosidase B-galactosidase deficiency | - Galactocerebroside accumulates in macs
60
What is following: Galactocerebrosidase B-galactosidase deficiency - Galactocerebroside accumulates in macs
Krabbe
61
What is adrenoleukodystrophy?
- Impaired CoA addition to long fatty acids | - Accumulation in adrenals and white matter
62
What is following: - Impaired CoA addition to long fatty acids - Accumulation in adrenals and white matter
Adrenoleukodystrophy
63
What is MS?
AI destruction of myelin AND oligodendrocytes | - HLA DR2 association
64
MS presentation?
1. Blurry vision in 1 eye 2. Vertigo and scanning speech (brainstem) 3. INO (MLF) 4. Hemiparesis 5. Bowel bladder sexual dysfunction
65
What is MLF?
Connects CN III to VI - When want to look left, CNVI fires pulling left Lateral rectus then shoots message to MLF telling CNIII to pull medial rectus of right eye in same direction
66
How does MLF damage present?
"INO" | Left eye can look left, but bright eye cannot as VI can no longer communicate with III
67
How to diagnose MS?
``` MRI: multiple plaques CSF: 1. Oligoclonal bands 2. Increased Ig 3. Lymphocytes 4. Myelin basic protein ```
68
When are grey areas seen in white matter?
MS - this is AI destruction of myelin which is the white matter
69
MS Rx?
Corticosteroids or acute and interferon B slows progress
70
What causes subacute sclerosing panencephalitis?
Measles | - Viral inclusion bodies in grey matter (neurons) and white matter (oligodendrocytes)
71
What is PML?
"Progressive multifocal leukoencephalopathy" - JV infx of oligodendrocytes - Usually from immunosuppression reactivating latent infx - Rapid neuro signs = death
72
Central pontine myelinolysis presentation?
Locked in syndrom
73
What does degeneration of cortical grey cause?
Dementia
74
What does degeneration of basal ganglia (deep grey) cause?
Movement disorder
75
What is APP? Problem?
"Amyloid precursor protein" - Protein that receptor on neurons is derived from - Alpha break down is normal - Beta breakdown = deposition of A-beta-amyloid
76
What is dementia?
Memory loss + cognitive dysfunction - loss of consciousness
77
What type of neurologic deficits seen in alzheimer's?
- None
78
What increases risk of sporadic alzheimer's? Decreases?
Increases: Epsilon4 allele of APOE (Think, 4 is more so higher risk) - Increases conversion of APP to beta form Decreases: Epsilon2 allele of APOE
79
Genetics of early alzheimer's?
1. Presenilin 1 mutation | 1. Down syndrome: APP gene found on chromosome 21 so increased risk
80
What is presenilin 1 mutation put you at risk for?
Early onset alzheimer's
81
What is diffuse cerebral atrophy with wide sulci / narrow giri?
Alzheimers
82
What is hydrocephalus ex vacuo?
- Apparent dilation of ventricles due to decreased brain mass - Seen in alzheimer's
83
What are neuritic plaques and what are they composed of?
Seen in alzheimer's: 1. A-beta amyloid from APP 2. Entrapped neuritic processes
84
What is cerebral amyloid angiopathy?
- Deposition of AB amyloid in vessels of brain: weakens walls increasing risk of hemorrhage
85
What are neurofibrillary tangles?
Composed of hyperphosphorylated TAU "microtubule associated proteins"
86
Histo of alzheimers?
1. Neurofibrillary tangles: hyperphosphorylated tau | 2. Neuritic plaques: AP amyloid / Entrapped neuritic processes
87
What is vascular dementia?
- Decreased blood flow to brain = many micro infarcts and injury causing dementia * By product of moderate global ischemia: pyramidal neurons in 3/5/6
88
What is Picks?
- Frontal (behavioral issues) and temporal (language issues) degeneration sparing occipital and parietal
89
What is dementia with early behavior and language problems seen in?
Picks
90
2 presentations of tau and diseases?
Picks: round tau aggregates | Alzheimer's: Neurofibrillary tangles: hyperphosphorylated tau
91
What is parkinson's?
Dopaminergic neuron loss in substantia nigra pars compacta (SNPC) of basal ganglia
92
What is following: | Dopaminergic neuron loss in substantia nigra pars compacta of basal ganglia
Parkinson's
93
What is striatum?
- Portion of basal ganglia sending +/- signals to cortex | - Receives input from cortex and SNPC
94
What does dopamine from SNPC do to striatum?
D1 binding on striatum: increased cortical stimulation | D2: decreases cortical inhibition (increased stimulation)
95
What can cause parkinson's?
Usually idiopathic but can be caused by MPTP in illicit drugs
96
Parkinson's presentation?
1. Pill rolling tremor at rest 2. Cogwheel rigidity 3. Expressionless face: can't move muscles 4. Brady / akinesia 5. Shuffling gait / postural instability
97
What are lewy bodies?
Inclusions seen in parkinson's compose alpha synuclein
98
Histo marker of parkinson's?
Lewy bodies composed of alpha synuclein
99
Is dementia seen in parkinson's?
- Can be a late sign | - If seen in first year diagnosis is lewy body dementia
100
What is lewy body dementia?
1. Parkinsonisms 2. Hallucinations 3. Dementia * **Cortical Lewy bodies: normally in SNPC in parkinsons
101
When are cortical lewy bodies seen?
Lewy body dementia
102
What is huntington's?
Knocking out of GABAergic (inhibitory) neurons in caudate of basal ganglia - Loss of inhibitory gaba = random firing on cortex = random movements (chorea)
103
What is following: Knocking out of GABAergic (inhibitory) neurons in caudate of basal ganglia
Hungtingons
104
What is striatum composed of?
Caudate + Putamen
105
What abuts the lateral ventricles?
Cauded nucleus with putamen cust under it: together they make the striatum
106
Cuase of Huntington's?
AD trinucleotide repeats of CAG - Anticipation seen: earlier in subsequent generations - Expansion is occurring during spermatogenesis
107
Huntington's presentation?
1. Chorea 2. Depression: suicide most common cause of death 3. Demention 4. Athetosis: slow, snake like movement of fingers
108
What is normal pressure hydrocephalus?
``` Increased CSF dilates ventricles strechting corona radiata causing: 1. Urinary incontinence 2. Dementia 3. Gait instability "Wet, wacky, wobbly" ```
109
What is following: 1. Urinary incontinence 2. Dementia 3. Gait instability
"Wet, wacky, wobbly" | - Normal pressure hydrocephalus
110
Normal pressure hydrocephalus treatment?
1. Lumbar puncture | 2. Peritoneal ventricular shunt
111
What are arachnoid granulations?
Outpouchings of arachnoid through dura to venous sinus allowing draining of CSF - Decreased absorption here results in normal pressure hydrocephalus
112
What is spongiform encephalopathy?
- Degenerative disease from prions
113
What is PrPC?
- Alpha conformation of prions normally found in human brains * Conversion to beta pleated PRPSC = prions and spongiform encephalopathy
114
Pathology of spongiform?
1. Beta pleated PRPSC converts normal alpha PRPC into beta 2. Beta sheets accumulate in cytoplasm 3. Creates intracellular vacules
115
When are intracellular vacuoles seen?
Spongiform encephalopathy
116
What is CJD?
- Sporadic form of spongiform encephalopathy | - Can arise from exposure to infected human tissue
117
CJD presentation?
1. Rapid dementia 2. Ataxia 3. Startle myoclonus 4. Death in 1 year 5. Spike wave complex on EEG
118
What is startle myoclonus?
Involuntary contraction of muscle with minimal stimulus
119
What is following: 1. Rapid dementia 2. Ataxia 3. Startle myoclonus 4. Death in 1 year 5. Spike wave complex on EEG
CJD
120
Which are the glial cells?
1. Microglials 2. Ependymal 3. Oligodendrocytes
121
Astrocyte tumor in kids and adults?
Kids: Pilocytic astrocytoma Adults: Glioblastoma multiforme
122
What is tentorium and what is significance relative to tumors?
Line in brain just above cerebellum: - Adult tumors occur above - Kids below
123
What is GBM?
"Butterfly glioma" - GFAP - Astrocytic tumor in adults - Cerebral hemispheres crossing midline (corpus callosum) - Central necrosis with pseudopalisading and endothelial proliferation
124
What is following: | - Central necrosis with pseudopalisading and endothelial proliferation
GBM
125
When in GFAP seen?
GBM: glial marker
126
What is meningioma?
- Benign tumor of arachnoid cells - Seen in women: ER + - Round mass attached to dura: seizures - Whorled appearance and psammoma bodies
127
What is following: | - Round mass attached to dura: seizures
Meningioma
128
- Whorled appearance and psammoma bodies
Meningioma
129
Schwannoma?
- Bening schwann cell tumor - CN VIII at cerebellopontine angle - S100 positive - NF2 bilaterally
130
Tumor seen in NF2?
Schwannoma
131
S100 +?
Schwannoma
132
Oligodendroglioma?
- Calcified in white matter of frontal lobes - Seizures - Makes sense in white matter as oligodendrocytes myelinate white matter "Fried egg appearance" Ol "EGG" odendroglioma
133
Calcified in white matter of frontal lobes?
Oligodendroglioma
134
Fried egg on histo?
Oligodendroglioma
135
Cerebellar tumor in kids?
Pilocysticastrocytoma
136
Pilocytic Astrocytoma?
- Cerebellar in kids - Cystic lesion with nodule growing on it - Rosenthal fibers - GFAP +
137
Rosenthal fibers?
Pilocytic Astrocytoma
138
Medulloblastoma?
- From granular cells of cerebellum - Small round blue cells: "Bluestoma" - Homer wright rosettes - Neuroectoderm in nature - Drop metastasis to spinal cord
139
- Small round blue cells | - Homer wright rosettes
Medulloblastoma
140
- Drop metastasis to spinal cord?
Medulloblastoma
141
Ependymoma?
- 4th ventricle in kids - Presents with hydrocephalus - Perivascular pseudo rosettes
142
- 4th ventricle in kids | - Presents with hydrocephalus
Ependymoma
143
- Perivascular pseudo rosettes?
Ependymoma
144
Craniopharyngioma?
- From epithelial remnants of rathke's pouch - Optic chiasm compression = bitemporal hemianopsia - Often calcified
145
What does upward protrusion of mouth become?
- Protrusion is known as rathke's pouch | A. pituitary
146
What does downward protrusion of base of brain become?
Post pit
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