Neuro Incorrects

Question 1

19yr M has BP 110/70, pulse 114. Sustained bifrontal contusions & basilar skull fracture in MVA. Repeat head CT later that day shows diffuse cerebral edema. The vent rate is adjusted to PaCO2 of 26-30mmHg. What is the most likely effect of this intervention?

Answer 1

increased cerebral vascular resistance

cerebral circulation is regulated by systolic BP and ABG levels (predominantly PaCO2), with ABG being most important regulation. [BP is key when 150+ or 50-].

lowered PaCO2 via hyperventilation> cerebral vasocontriction> dec cerebral BV>dec ICP, which is key for mech vent pt with cerebral edema.
*CO2 is a potent vasodilator of cerebral vasculature.

Question 2

what is another way you can induce dec ICP in this patient on mech vent from MVA?
**pt has bifrontal contusions w/ basilar fracture & clear cerebral edema on CT

Answer 2

decreased metabolic demand

induced sedation, therapeutic hypothermia> decrease metabolic demand> reduce cerebral BV> reduce ICP

Question 3

62yr hospitalized F evaluated for muscle weakness. 2wks ago pt had pyelonephritis. She was tx with IV fluids, vasopressors, antibiotics, and was mech vent due to resp failure. Hemodynamics have improved, but she is unable to get off vent from resp muscle weakness. Significant extremeity weakness, diffuse mild atrophy of extremities muscles. B/l U/L DTR dec. What is the cause of patient’s condition?

Answer 3

Dx: critical illness myopathy or critical illness polyneuropathy

sepsis> crit ill> neuromuscular weakness via 1) myopathy: dec muscle membrane excitability= atrophy of myofibers 2) polyneuropathy: dec nerve excitability w/ Na channel inactivated, and axonal degeneration via injury to microcirculation of inflame mediators.

presents as symmetric weakness greater in proximal > distal muscles w/ dec DTR. Diagnosised commonly when pts unable to be liberated from vent w/ chest wall weakness.
tx: prevent further complications, rehab to improve muscle strength

Question 4

56yr M dies with aspiration related complications. 5 days ago admitted for R weakness, sensory loss, difficulty speech/swallowing. CT shows hypodensitiy of L frontoparietal region. Autopsy shows loose, spongy tissue from abnormal area that stains with lipids. What cell type is predominately stained in this patient?

Answer 4

lipid stain finds foamy macrophages» microglial cells, of pts subacute cerebral infarct.

microglia are predominate cell in necrotic area 3-7 s/p ischemia: phagocytize myelin (lipids) and other debris

w/in 24hrs: red dead neurons, irreversible damage sign.
1-2 days: neutrophils
3-7 days: microglial (derived from yolc-sac monocytes: MESODERM derivated)» stain lipids, and would be key for liquefactive necrosis

Question 5

what lineage is the microglia originate?

Answer 5

mesoderm

Question 6

5yr M PMH speech delay & recurrent ear/pulm infections, is having recent slurred speech. Pt’s eyes are “not moving smoothly”. Exam shows numerous superficial nests of distended capillaries on face and ears that blanch w/ pressure. Pt’s condition is most likely due to genetic defect affecting what process?

Answer 6

DNA break repair»

facial telangiectasias + recurrent infections + cerebellar dysfxn (slurred speech)= ataxia-telangiectasia (AT)» AR inheritance of defective ATM gene that usually detects DNA damage. dx usually around 3-5 when T’s start to appear on face/eyeballs

“superficial nests of dilated blood vessels”= telangiectasia, little red lines

**neurons are highly prone to oxidative stress, and usually 1st manifestation of AT are cerebellar degeneration: unsteady gait, speech patterns, impaired head/eye coordination (oculomotor apraxia)

Question 7

recurrent infections + speech delay/slurred speech + distended capillaries that blanch with pressure

Answer 7

Ataxia Teleangiectasia; defective ATM gene= defective DNA break repair

Question 8

what disorder is characterized by defective sphingolipid degeneration?

Answer 8

Niemann-Pick, AR
hypotonia/areflexia + hepatosplenomegaly + cherry-red macula spot

Question 9

54yr F w/ progressive fatigue and weakness for past 2 months, difficulty mainly with rising from chair w/ lower extremity weakness. B/l dec strength in proximal muscles of lower extremity w/ normal tone. Quad reflex dec. Xray shows pt has small cell lung cancer. What is the most likely cause of weakness?

Answer 9

Lambert-Eaton myasthenic syndrome» antibodies against presynaptic Ca2+ channels at NMJ.

LEMS: proximal muscle weakness w/ reduced DTR in lower extremities.
**not MG> typically involves extraocular muscles (ptosis, diplopia) and bulbar (dysphonia, dysphagia) before affecting limbs, reflexes remain intact.

Question 10

21yr F w/ long history of episodic headaches, dizzy, gait imbalance. Headaches in occiptal region and last for several hours. MRI shows low-lying cerebellar tonsils extending below FM into vertebral canal. What is the most likely cause?

Answer 10

congenital malformation> pt has Chiari 1 malformation. most common, most benign.

**headaches are from meningeal irritation, compression of tonsils gives cerebellar dysfxn (dizzy, ataxia)

Question 11

10yr boy w/ n/v, headaches, ataxia, vision changes. Headaches awaken from sleep, happening for 6wks. MRI shows tumor in cerebellum. Biposy shows well-differentiation neoplasm with hair-like glial cells w/ eosinophilic corkscrew shaped fibers and granular bodies. Most likely diagnosis?

Answer 11

pilocytic astrocytoma» most common pedi brain tumor, arising w/in infratentorial, esp in cerebellum» headaches, n/v, ataxia.

histology:
astrocytes–> bipolar, hair-like processes w/ ovoid nuclei, processes contain GFAP (making it glial lineage)
Rosenthal fibers-> proteinaceous, eosinophilic cytoplasmic inclusions w/ corkscrew appearance

Question 12

perivascular psedorosettes are found in what malignancy?

Answer 12

ependymomas» ependymal cells arranged around central BV.
poor prognosis. normally found in 4th V

Question 13

Homer-Wright rosettes are found in what neuro malignancy?

Answer 13

medulloblastoma» small, round, blue tumor cells arranged around a central core of neuropil (fibrillary material w/ neuronal processes).

**can also be found in neuroblastomas (embryonal neuroendocrine tumors), typically found in adrenal medulla/sympathetic ganglia.

Question 14

16yr M w/ progressive gait instability, dysmetria, dysathria for past several years. Symtoms worse can no longer play bball. His brother developed similar symptoms and died at 21. Exam shows b/l motor weakness, and no DTR, joint position, or vibration sense. MRI shows degeneration of posterior columns and spinocerebellar tracts. What other condition has neuro manifestations similar to pt’s disease?

Answer 14

pt dx Fredrick Ataxia, AR via GAA trinucleotide repeat of frataxin gene
-no spinocerebellar= ataxia
- no dorsal column= position/vibrate
-peripheral degeneration= weakness, loss of DTR

Vit E deficiency» caused by fat malabsorption (CF, pancreatitis, cholestasis) or genetically abetalipoproteinemia» presents w/ neuromuscular dysfxn (spinocerebellar, dorsal, peripheral nerves, myopathic muscle weakness) + hemolytic anemia (free radical damage of RBC membranes)
**VitB12 can also present similar to FA w/ subacute combined degeneration of dorsal & lateral spinal columns.

Question 15

what is the presentation of acute intermittent porphyria in regard to neuro?

Answer 15

peripheral neuropathy (numbness, paraesthesias) + acute attacks of abd pains

Question 16

what congenital malformation results in a characteristic enlarged head circumference, and a dilated 4th ventricle?

Answer 16

danny-walker malformation» hypoplasia/absent cerebellar vermis + cystic dilation of 4th V w/in posterior fossa (+- agenesis of corpus callosum, face/heart/limb malformations)

presents in infancy w/ developmental delay, progressive skull enlargement, non-communicating hydrocephalus w/ atresia of foramina Magendie/Luschka> elevated ICP (irritable, n/v).
**test taking strategy. Dandy-Walker most likely gonna show a posterior/inferior CT vs Arnold-Chiari most likely sagittal CT to show tonsillar movement.

Question 17

75yr M in office for memory loss, increased confusion for 6 months. Unable to manage finances, gets lost, poor coginition on exam. T2-weighted MRI reveals multiple hyperintensities in diffuse cerebral white matter + subcortical gray matter hyperintensities in b/l thalamus. Diagnosis?

Answer 17

vascular dementia» rather abrupt cognitive decline w/ prominent executive dysfunction dysfxn + scattered lesions in white matter + thalamus issues.

1) via large vessel atherosclerosis, narrows lumen> inc risk for thromboembolism> leads to stroke, MRI shows discrete cortical infarct
2) via small vessel, arteriolosclerosis (thickened arterioles)> microaneurysms, often affecting subcortical regions w/ less collateral BF (thalamus, basal ganglia, hippocampus)
3) via cerebral amyloid angiopathy> beta-amyloid deposits, inc fragility> **spontaneous, lobar intracranial hemorrhage, or multiple small infarcts presenting as VaD.

Question 18

what is the onset of Alzheimer dementia compared to vascular?

Answer 18

more insidious onset for AD vs vascular dementia.
MRI for Alz will show parietotemporal cortical atrophy w/ NO evidence of structural disease.

Question 19

what cerebral atrophic regions are associated with Alzhemier’s?

Answer 19

medial temporal (hippocampus, inability for new memory formation) and parietal cortices

*disproportionate atrophy of parietal + occipital cortices= atypical variant Alzhemier’s.

Question 20

62yr F w/ double vision, esp reading at night. At first intermittent, worsened over 2 wks, now constant. Also difficulty chewing. Feels better in AM. Exam shows b/l ptosis; weakness in add R, AB on L is present. Strength 4/5 in proximal muscles upper & lower. DTR 2+ thruout. What changes involving the postsynaptic muscle cell most likely explains pt symptoms?

Answer 20

reduced amplitude of motor end plate potential» pt has MG (fluctuating, fatigue weakness in bulbar fashion– eyes, jaw + proximal extremities.

autoantibodies for postsynaptic AchNr> reduced end plate potential for Ach release> threshold potential not reached> muscle cells do not depol frequently> reduced amplitude

**NOTE: AP amplitude, propagation velocity, refractory period of muscle cell are INTRINSITC properties of muscle cells> all would be normal in MG as the NMJ impaired. BUT compound muscle AP decreases w/ repeated excitation in patients with MG via fewer myofiber depol

Question 21

Pt is being treated for MG, reports improvement of symptoms. But has begun to have abd cramps, nausea, sweating, diarrhea. What agent can control these new symptoms?

Answer 21

glycopyrrolate (selective muscarinic antagonist: hyoscyamine or propantheline too)» pt began having cholinergic toxicity (DUMBELS) from her cholinesterase inhibitor (pyridostigmine).

**muscarinic overstimulation since cholinesterases are non-specific for increasing Ach only> acts on both AchNr, AchMr.

Question 22

what are the signs of muscarinic overstimulation/cholinergic toxicity

Answer 22

D: diarrhea
U: urination
M: miosis (pupil constrict)
B: bronchospam, bradycardia
E: emesis
L: lacrimation
S: salivation

look for this with organophosphates, and MG pt on meds to correct it.

Question 23

43yr F w/ pain, tingling in first 3 digits of both hands that worsens at night, often preventing her from sleeping. No problems w/ legs. PMH CKD 2/2 IgA nephropathy, on hemodialysis. Exam shows diminished sensation in both hands over palmar aspect of thumb, index, middle fingers, radial half of ring finger. Most likely underlying her current condition?

Answer 23

nerve compression w/in anatomic compartment> medial nerve compression> carpal tunnel syndrome.

given her dialysis, pt developed median nerve compression via deposition of B2 microglobulin amyloidosis in carpel tunnel.

Question 24

in what setting would you see endomysial inflammatory infiltration/

Answer 24

found on muscle biopsy in polymyositis> myopathy w/ proximal muscle weakness

Question 25

in what setting would you see endoneurial arteriole hyalinization?

Answer 25

DM> “diabeteic microangiopathy”> commonly starts distal, symmetric peripheral polyneuropathy starting in the feet.

Question 26

in what setting would you see endoneurial inflammatory infiltration (+-multifocal)?

Answer 26

Guillian-Barre syndrome> endoneurial inflammatory infiltration w/ multifocal demyelination. generally presents with ascending motor weakness.

Question 27

what are the age related sleep changes?

Answer 27

decr total sleep time
incr nighttime sleep latency (N3)
incr fragmented sleep
earlier wake-up times
unintentional daytime naps
subjective reports of insomnia

**even tho pt might have PMH of depression, in order to qualify as depression, pt has to have current symptoms of depression to have sleep related depression changes.

Question 28

21M w/ impaired balance, tremor, difficulty speaking. Symptoms developed slowly over several months. Elevated serum transaminases. Viral Hep is neg. He has a sibling diagnosed at young age w/ progressive neuro disease. Which of the following diagnostic studies would be most helpful in confirming diagnosis of pt?

Answer 28

slit lamp examination> pt has Wilson’s disease.

AR mutation of ATP7B> hepatic copper mutation> damaged hepatocytes leak> Cu deposits in tissues (basal ganglia, cornea)
*nearly all pts have green/brown cooper deposits in descemet membrane of cornea= Kayser-Fleischer rings, found on slit lamp exam
*confirm diagnosis w/ low serum ceruloplasmin, tx: trientine, penicillamine, Zinc

Question 29

what are the 3 areas of clinical findings for patient’s with ATP7B mutation?

Answer 29

pt has Wilson’s disease

1) hepatic: acute liver fail, hepatitis, cirrhosis
2) neurological: parkinsonism, gait changes, dysarthria
3) psychiatric: depression, personality changes, psychosis

Question 30

55yr M w/ overwhelming pneumonia dies in hospital. He had muscle weakness & gait changes prior to hospital. Autopsy shows atrophic precentral gyrus and thin anterior roots of spinal cords. Microscopy shows severe loss of neurons in ant horn of spinal cords & in hypoglossal/ambiguus cranial n nuclei. Corticospinal tracts stain faintly w/ myelin stain. Autopsy is most suggestive of what condition/

Answer 30

Amyotrophic Lateral Sclerosis (ALS: Lou Guerig’s disease)» presence of both losses:
UMN> atrophy of precentral motor gyrus, degeneration of corticospinal tracts= stiffness, hyperreflexia
LMN>thinning of anterior roots, neurogenic atrophy of skeletal muscles= bulbar symptoms (hypoglossal, ambiguus, motor trigeminal)

toxic intracellular protein inclusions accumulate in motor neurons> trigger apoptosis.
**will see BUNINA BODIES, eosinophilic cytoplasmic inclusions, PAS+ in remaining neurons. apoptotic neurons replaced by glial cells.

Question 31

what is the most common cause of death in pt with ALS

Answer 31

respiratory failure w/ diaphragmatic weakness, ineffective cough, chronic aspiration» can have an overwhelming pneumonia.

Question 32

82yr M found unresponsive. EMS arrives, pt is obtunded & responds to painful stim only. Pt dies in route to hospital. Autopsy reveals extensive atherosclerotic dx of coronary & internal carotids. Histopathology shows R MCA territory w/ shows neurons w/ intesensly eosinophilic cytoplasm & nuclear fragmentation. When did pt’s cerebral injury most likely occur?

Answer 32

12-24hrs» seeing red, dead neurons (eosinophilic cytoplasm, pyknotic nuclei, loss of Nissl substance); pt had ischemic stroke w/ lack of profusion to cerebral tissues

24-72: neutrophils
3-7 days: macrophages/microglial cells, phagocytosis begins
1-2wk: reactive gliosis, vascular proliferation around necrotic area= liquefactive necrosis
2+ wks: glial scar; cystic area surrounded w/ dense glial fibers after 1 month

Question 33

56yrF in ER w/ several days of progressive dyspnea, productive cough, fever. Son found her very SOB and obtunded. PMH HTN, DM2, chronic RA. Exam b/l pneumonia, severe RDS. Pt mech vent, started on antibiotics. Repeat exam 2hrs later shows she developed areflexic, flaccid paralysis of all extremities. What is the most likely cause of neuro deficits in patient?

Answer 33

vertebral subluxation» via extension in endotracheal intubation, developed sudden-onset quadriparesis.

long-standing RA frequently involved C-spine> joint destruction w/ vertebral malalignment, often the atlantoaxial joint (C1/C2)» look for acute spinal cord injury resulting in flaccid descending paralysis w/ decreased/absent reflexes below the compression due to spinal shock> paralysis eventually becomes spastic ensuing days to weeks.

**NOTE: pt kinda had Guillian-Burre type but remember it starts in the lower extremities, ascends upwards.

Question 34

54M w/ worsening memory impairment over several months, withdrawn, slow to answer questions. PMH HIV, opportunistic infections, inconsistent RT meds. Strenght, DTR, sensation normal. MRI shows diffuse cerebral atrophy w/ no focal mass lesions or areas of demyelination. Viral proliferation in which of the following CNS cells is most likely involved in pt’s disease process?

Answer 34

macrophages» pt has HIV associated dementia, looks for HIV-infected microglia fusion, forming multinucleated giant cells in CNS.

HIV dementia is commonly subcortical dementia w/ mood, attention, memorial, psychomotor dysfunction. HIV preferentially affects and replicates in CD4 T cells in peripheral blood, but CNS infection is associated with viral tropism (ability to infect different cell types) to microglia & macrophages» allowing to penetrate brain parenchyma. Macrophage tropic “M-tropic” version of the virus becomes “compartmentalized” in CNS and evolves independently from strain in blood.

**HIV does not infect neurons, nor oligodendrocytes.

Question 35

what virus replicates in the neuron, known as N-tropic, affecting the CNS?

Answer 35

lyssaviruses of rhabdovirdiae» rabies (enveloped, ssRNA, linear, helical capsid)

Question 36

what virus replicates in the endothelial cells of the CNS, known as E-tropic?

Answer 36

CMV (HSV5) **all herpes virus are enveloped, dsDNA, linear

Question 37

82yr F w/ memory loss. Lives w/ daughter now who’s in charge of financnes, healthy proxy. 2yrs ago pt forced to stop driving, getting lost, minor MVAs; forgetting recent events. Still enjoys reminiscing old times, playing bingo at church. What pathological finding is in this pt?

Answer 37

neuritic plaques» pt has Alzhiemer’s dementia, insidious memory loss, esp recent events.

typical findings of Alzheimer’s: AB amyloid plaques (extracellular), neurofibrillary tau tangles (intracellular)

**NOT LEWY BODIES= PARKINSONS. booooo

Question 38

55yr man with HIV in ER w/ 3wks of increasing headache, fever, vomitting. Exam shows low BP, neck stiffness. Pt deteriorates, dies. Autopsy shows diffuse gelatinous exudate covering base of brain. Cut lesions show marked ventriculomegaly & frontal lobe infarcts but no intraparenchymal mass lesions. What is the diagnos?

Answer 38

tuberculosis infection» TB-meningoencephalitis.

**THICK, GEL EXUDATE most prominent in BASE OF BRAIN= TB. often encases cranial nerves> nerve palsies; or invading Willis> stroke

common to also have:
1) vasculitis of cerebral arteries> mutiple b/l brain infarctions, generally periventricular cerebral areas.
2) hydrocephalus w/ obstruction CSF via tubercular proteins» inc ICP, ventriculomegaly (headache, n/v)

**NOTE: CNS syphilis presents temporal lobe infestations; CNS lymphoma has single large mass in cerebral parenchyma; toxoplasma encephalitis w/ slow progressive headache, multiple ring enhancing intraparenchymal lesions in brain

Question 39

59yr M ER w/ diplopia started several hours ago. PMH poorly controlled DM, R knee OA, PUD. Exam shows R ptosis, w/ R pupil in inferolateral position. Pupils equal and reactive to light. Patient’s condition is most likely due to?

Answer 39

nerve ischemia 2/2 poorly controlled DM» “diabetic ophthalmoplegia”

diabetic CN3 mononeuropathy presents as acute onset diplopia, assumes “down & out”, spares pupil constriction.

**somatic CN3 controlling motor movement located centrally in nerve; autonomic CN3 controlling pupil constriction is located peripherally. ischemic nerve damage predominately affects CN3 core» this is the biggest distinction btw diabetic mononeuropathy 2/2 nerve ischemia vs. nerve compression (dilated pupil, ptosis, down & out—> uncal herniation, neoplasms, PCA/PCom aneurysms)

Question 40

3wk boy in NICU for apnea. Born 27wks gestation, 2lb 2oz. Past 2wks pt been stable on minimal resp support via nasal cannula but has intermittent episodes of no respiratory effort for ~30sec at time» bradycardia, desaturation. Pt recovers spontaneously or w/ nurse stimulation. Pt well btw episodes. ABG is normal. Exam shows clear breath sounds, easy WOB. U/s head normal. Clinical findings are most likely caused by what abnormality?

Answer 40

central stimulatory neurons» pt has apnea of prematurity, central apnea at occurs in nearly all preterm <28wks w/ immature central resp centers. tx: methylxanthines can stimulate resp neural input

respiratory centers in medulla & pons> medulla resp centers are stimulatory neurons triggering inspiration (dorsal respiration group) and expiration (ventral respiration group)» send impulses to diaphragm to intercostal muscles.
**medulla receives input from pons of RR and depth of inspiration (via chemoreceptors, proprioceptors…ABG abnormal, think peripheral chemoreceptor changes).
» can be consciously overridden by cortex (intentional sigh, breath-holding)

Question 41

42yr F w/ spouse for eval of abnormal movements. Pt having involuntary facial grimaces, extremity fidgeting, frequent anger outburts. She smoked cigarrettes and used illicit drugs in college, but not since then. No PMH, no meds. Father died of neuro disorder at 55. Exam shows intermittent, fidgety, jerky movements of hands. MRI is order. What would be characteristic to find on neuroimaging?

Answer 41

enlargement of frontal horns of lateral ventricles» pt has Huntington’s
most commonly see atrophy of caudate/putamen» enlargement of lateral ventricles= ex vacuo hydrocephalus

**loss of inhibitory GABA neurons= dec regulation of movement/behavior

Question 42

what pathological condition presents w/ b/l hippocampal atrophy?

Answer 42

early-onset Alzheimer’s disease» look for someone w/ Trisomy 21

Question 43

26yr M in ER s/p high speed motorcycle accident. Thrown several feet when collided w/ car. On arrival, pt profoundly comatose. Head CT performed w/in hr of arrival shows no abnormalities. Pt dies several hours later. Autopsy shows widespread axonal swelling, predominately at gray/white junction. IHC staining reveals accumulation of a-synuclein & amyloid precursor proteins in these axons. What is the most likely cause of these findings?

Answer 43

interruption of white matter tracts» 2/2 diffuse axonal injury (traumatic brain injury) via blunt force trauma or abrupt accel-decel injury» transfer of force leads to immediate shearing of white matter tracts, and subsequent axon breakage> normal axonal transport is inhibited, leading to accumulation of proteins (amyloid precursors/synuclein) & axonal swelling at point of injury.

**DAI is visible as widespread axonal swelling most pronounced at gray-white matter junctions on MRI. CT has low sensitivity for diagnosis and often normal. Pts usually comatose, and prognosis is poor.

Question 44

what does the CNS histopathology look like for systemic hypotension/cardiac arrest?

Answer 44

diffuse cerebral hypoperfusion» watershed zone infarctions/diffuse edema w/ BLURRING of gray-white junction on imaging. Ischemic neurons release glutamate» overactivation of NMDAr w/ continuous membrane depolarization> results in neuronal damage, via excitotoxicity. Look for RED DEAD NEURONS w/ intense eosinophilic cytoplasm.

note: axonal transport proteins would not be likely as axonal transport is not entirely inhibited.

Question 45

28yr M found unresponsive by roommate. Pt returned late after a party, this morning is unable to wake. Pt w/o respirations and no pulse> declared dead. Autopsy shows hemorrhage in basal ganglia, and midbrain extends to 3rd V. No arteriosclerosis, no fibrinoid necrosis of artieroles. Scattered areas of infarcted suendocardial myocardium also seen. The substance taken has what snyaptic effect that predisposed pt to death?

Answer 45

imparied presynaptic NT reuptake» pt has cocaine overdose.

sudden, unexpected death w/ large hemorrhagic stroke + scattered myocardial infarctions= cocaine toxicity> impairs the reuptake of norepi/dopamine.

cocaine> stroke:
1) stimulation of cerebral a vasospasm 2/2 increased intrasynaptic dopamine
2) inc BP (vasoconstriction & symp tone)» encouraged dissection of large cerebral arteries, rupture small cerebral vessels> LACUNAR infarcts of young pts.
3) incr platelet activation> encourages thrombus formation
4) incre myocardial O2 demand (via all symp stimulation)> propensity for myocardial ischemia/MI.

Question 46

34yr F hx dec sensation in her legs x2days. Signficant fatgiue w/ exercise. 6 months ago had episode of blurring vision resolved spontaneously a few days later. PMH psoriasis, w/ topical steroids. Exam reveals dec pain/light touch in both legs below umbilicus. Mild b/l spasticity noted. What pathologic brain lesion is MOST specific for patient’s disease?

Answer 46

perivenular inflammatory cells» pt has MS.

MS plaques are characterized by perivenular inflammatory infiltrates of autoreactive T cells/macrophages directed against myelin of oligodendrocytes. patchy demyelination occurs followed by astrocyte hyperplasia (glial scarring).

**can also find microglial nodules in MS, but NOT specific. can also be found in HIV encephalopathy, viral infections…reaction lesions that occur in setting of inflammation.

Question 47

4yr boy ER for dehydration, dec oral intake. Pt has no vaccination. Vitals show tachy, dec skin turgor and sunken eyes. Jaw muscles are tight, increased tone thru body, patellar reflex 3+. Small healed wound on lower leg–boy fell on piece of chain-link fence in backyard. Release of what neurotransmitter is most likely directly impaired in this patient?

Answer 47

glycine» pt has C. tentani via tetanus toxin, tetanospasmin.

toxin binds presynaptic membranes of peripheral motor neurons> migrates via retrograde axonal transport to CNS inhibitory in spinal cord/brainstem> inhibit release of glycine & GABA> increased activation of motor neurons= muscle spams, hyperreflecia, trismus, risus sardonicus, opisthotonos.

**remember than Botulinum toxin prevents release of Ach, giving flaccid paralysis.

Question 48

What neurotransmitter on postsynaptic membrane is most likely involved in the increased intracellular calcium concentration, esp as it relates to hippocampal neurons in memory/learning potentiation?

Answer 48

glutamate NMDA receptors (sodium and calcium in, potassium out)> net depolarization» increased Ca + second messenger signaling (PKC)> regulate synaptic plasticity. “long term potentiation” for memory, learning, addiction

**acute blockade of NMDA= ketamine, amnestic property
chronic blockade of NMDA= memantine, neuroprotective effects of dapening glutamate-induced excitotoxicity (neuron apoptosis due to calcium overload)

Question 49

19yr obese F w/ bifrontal headaches and early morning n/v 4wks. Pt is alert and cooperative. BP 114/78, pulse 80. BMI 31. Fundoscopy shows b/l papilledema. Visual 20/20. Neuro exam & CT shows no abnormalities. What is the most likely explanation of pt symptoms?

Answer 49

cerebral venous HTN» headaches + papilledema= increased ICP, generally idiopathic intracranial HTN (w/ young age, obese, no comorbidities, clear CT)

congestion of venous system (cerebral venous HTN) either due to clot or primary intracranial P= decreased CSF resob= increased ICP

Question 50

58yr M in ER w/ sudden R sided weakness. No sensory loss, speaking/swallowing changes, nor ataxia. Pt previously told had HTN, but loss to f/u. Takes no meds. Exam shows intact CN, sensory fxn. Pt has 3/5 muscle strength on R side. CT w/o contrast reveals no abnormalities. 4wks later, repeat brain imaging shows 9mm, fluid-filled cavitary lesion in L internal capsule. Pt’s condition most likely caused by?

Answer 50

HTN arteriolar sclerosis» pt has pure motor hemiparesis and small cavity lesion in internal capsule= lacunar infarcts, primarily affecting small, penetrating arterioles supplying deep brain (basal ganglia, pons) & subcortical (internal capsule, corona radiata).

**LACUNAR INFARCTS primarily associated w/ chronic HTN> promoting lipohyalinosis, microatheroma formation, and hardening/thickened walls (HTN arteriolar sclerosis)> progressive narrowing arteriolar lumen, predisposes to vessel occlusion.

*note: due to small infarcted size (<15mm), acute CT imaging may not reveal the hypodensity of ischemic stroke…but several weeks later will see necrotic lesions turn into cavitary spaces filled with CSF surrounded by scar tissue (“lacuna”)

Question 51

Describe the length-dependend axonopathy associated with poorly controlled DM?

Answer 51

clinical features show 1st in longest nerves, predominantly affecting the feet.

1) small fiber injury: pain, paresthesia, allodynia “positive symptoms”» small, unmyelinated C fibers
2) large fiber injury: numbness, loss of sensory stimulation, ataxia, diminished ankle reflex “negative symptoms”» large sensory fibers

Question 52

65yr F found dead in house. Family notes pt had difficulty walking over past few months. Hx of AFib, takes anticoag. Autopsy reveals bruised scalp, large epidural hemorrhage w/ brain herniation. Spinal cord shows symmetric myelin later vacuolization and axonal degeneration involving posterior columns & lateral corticospinal tracts. What is the most likely cause of spinal cord findings?

Answer 52

Vit B12 deficiency» myelin degeneration in dorsal columns + lateral corticospinal tracts, likely cause of ataxia (subacute combined degeneration).

SACD: diminished position/vibration sense + ataxia + muscle weakness + spastic paresis + megaloblastic anemia (impaired DNA synthesis in hematologic cells)

**vs ALS: will see lateral corticospinal tract, but will also see anterior horn damage (UMN, LMN), SPARED sensory pathways.

Question 53

what are the characterisitcs of UMN lesion?

Answer 53

hyperreflexia, hypertonia, spastic paralysis, clasp-knife rigidity, Babinski present

Question 54

what are the characteristics of LMN lesion?

Answer 54

hyporeflexia, hypotonia, FLACCID paralysis, muscle weakness, muscle fasciculations, muscle atrophy, no Babinski

Question 55

Rapid correction of electrolyte abnormalities in someone w/ chronic hyponatremia> leads to osmotic demyelination syndrome “central pontine myelinolysis”. Demyelination namely occurs in the pons, but can also affect what other areas?

Answer 55

extrapontine sites: basal ganglia, cerebral white matter.

look for spastic quadriplegia, pseudobulbar palsy, locked in syndrome

Question 56

Narcolepsy is a chronic sleep disorder characterized by frequent, overwhelming urges to sleep. Commonly associated with w/ cataplexy, the sudden loss of muscle tone occuring w/ intense positive emotions/trigger. It results from the depletion of what neurons, and in what brain region?

Answer 56

results from depletion of hypocretin (orexin) secreting neurons in the lateral hypothalamus, key involvement in maintaining wakefulness.

experience intrusions of REM sleep phenomena during sleep-wake transitions: sleep paralysis, hallucinations.
DX: confirmed with low CSF levels of hypocretin1 or shortened REM sleep latency on polysomnography.

Question 57

9 month boy for well-check. Mother says pt cannot roll over, sit w/ support, nor crawl. Pt can reach for toys w/ L hand, but not R. Born 28wks, low Apgar scores, low birth weight; NICU for 3 months. Head/length 50th percentile, weight is 15th. Vitals WNL. Exam shows R hand fisted shut; muscle tone, DTR increased in R arm/leg. What is the most likely cause of patient’s condition?

Answer 57

periventricular focal necrosis» aka periventricular leukomalacia, or basal ganglia lesions» pt has cerebral palsy

premature infant w/ gross motor delay, hypertonia, hyperreflexia= cerebral palsy» watershed areas have sparse vascularization of periventricular white matter> ischemia disrupts normal myelination> neuronal cell death/cystic necrosis; preterm can also have increased risk of intraventricular hemorrhage= further development of CP

Question 58

what is the CNS pattern for premature infant w/ cerebral palsy presenting with global neuro deficits involving b/l extremities?

Answer 58

diffuse cerebral atrophy > periventricular focal necrosis (usual CP presentation)

Question 59

mesial temporal sclerosis is a characteristic MRI finding for?

Answer 59

focal temporal lobe epilepsy»
temporal lobe is responsible for sensory processing/memory formation

**unlike cerebral palsy, where predominantly motor dysfxn

Question 60

what are the warning signs of abusive head trauma (shaken baby)?

Answer 60

multiple subdural hemorrhages
retinal hemorrhages
posterior rib fractures (grasping baby too tight)
injuries inconsistent w/ history for developmental age.

**babies cannot roll until 4mons
**no fall from bed height will not cause sufficient large intracranial hemorrhages> altered mental status.

Question 61

Damage above red nucleus typically presents w/ decorticate posturing–what sites are most common culprits?

Answer 61

cerebral hemisphere, internal capsule

Question 62

Damage below red nucleus typically presents w/ decerebrate posturing– what sites are most common culprits?

Answer 62

pons, or nucleus itself w/in midbrain.

**yes the substantia nigra is directly below the red nucleus, but this will be more excessive inhibition of thalamus> Parkinson concerns. NOW a Parkinson patient can present w/ decerebrate posturing given proximity, but it won’t be an accurate answer for someone w/o Parkinsonian features.

Question 63

21yr M w/ weakness and gait disturbances. Few months been having trouble opening lids, trouble releasing grip. Tripped and fallen up stairs several times. Male pattern baldness is present on exam. No cardio abnormalities. Muscle biopsy shows muscle atrophy of type 1 fibers. This patient most likely has a form of what neuromuscular disease?

Answer 63

muscular dystrophy» AD CTG repeat expansion in DMPK gene» untranslatable mutant mRNA» disorganized tubules (type 1 fiber atrophy)= mytonic dystrophy

characteristic features: cataracts, insulin resistance, early-onset frontal balding, small gonads

Question 64

68yr M ER by daughter w/ AMS. Past 2 days been seeing strangers near house. Intermittently confused, difficult to arouse, distracted. No headaches, no focal weakness. No psych PMH, only seasonal allergies–which have been increased since daughter moved in. BP 140/85, pulse 88/min, respirations 12/min. Exam shows somnolent but arousable via voice. Not oriented to time or place. Pupils EROL. B/l upper & lower sensation, stregnth, DTR, pain WNL. Cell counts, chemistry studies WNL. What is the most likely cause of current state?

Answer 64

AMS (impaired consciousness, disorentiation, hallucinations) are consistent with delirium» acute onset + fluctuation distinguish delirium from dementia/psychosis.

medication effect of antihistiamines (or anticholinergics, benzo, opioids, sedative-hyponotics)» are psychoactive, carry high risk for delirium.

**not Lewy body dementia w/o bradykinesia, early executive fxn loss. does have hallucinations.

Question 65

what is the characteristic finding for liquefactive necrosis?

Answer 65

release of lysosomal enzymes

> > in brain tissue, release from ischemic neurons and responding inflammatory cells results in the tissue degradation in affected region–> creates cystic cavity
** in severe infections, like bacterial abscess, massive release of hydrolytic enzymes from reacting inflammatory cells= liquefactive necrosis.