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Neuro B5 - WLB > Kraft Block 5 > Flashcards

Kraft Block 5 Flashcards

1
Q

What are the gross brain features in HD?

A
  • Small brain
  • Atrophic striatum
    • Caudate nucleus is very small/flat
  • Atrophic frontal lobe
  • Dilated lateral/3rd ventricles
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2
Q

What is the gross brain grading in HD based on?

A
  • Level of atrophy can be used to determine grade
    • 0-1: no gross atrophy
    • 2: some atrophy but caudate still remains convex (bulges into ventricle)
    • 3: caudate is flat
    • 4: caudate becomes concave
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3
Q

What are the microscopic features of HD?

A
  • Severe loss of striatal neurons, esp. medium spiny neurons
    • Degree of degeneration directly related to severity of clinical Sx
  • Extensive fibrillary gliosis (Astrocyte proliferation)
  • Huntingtin protein aggregates in neurons
    • Gene for this protein is abnormal –> expansion of trinucleotide sequence CAG
    • form a basket-like structure of long proteins
                                                  à catches other proteins
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4
Q

What cell types are present/absent in microscopic examination of the HD brain?

A
  • Cell types
    • Neurons: none present in HD
    • Oligodendrocytes: lots
      • compact chromatin with halo around
    • Astrocytes: lots
      • dark circle with non-compact chromatin, no halo
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5
Q

What does the presence of ubiquitin mean?

A
  • Ubiquitin stain = surrogate marker
    • misfolded protein is not removed like it should be
    • stays attached to ubiquitin
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6
Q

What is the pathogenesis of HD according to Dr. Krafts?

A
  • Loss of neurons in BG
  • Spiny striatal neurons dampen motor activity
    • Taking off the brakes
    • Lose these –> get increased motor output –> Choreathetosis
  • Cognitive changes related to neuronal loss from cortex
    • Prefrontal loop in BG
    • Loop involved in personality and behavior
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7
Q

What are the common causes of global cerebral ischemia?

A
  • Hypotension
    • diminish blood flow to the entire brain
  • “Watershed” infarcts
    • areas at the border of two different blood supplies
  • laminar necrosis
    • “band like” area of hypoxic injury in one area
  • diffuse necrosis (liquifactive)
    • global damage to entire brain
    • “respirator brain” does not get enough blood supply to brain on respirator
    • really bad hypotensive episode
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8
Q

In terms of global cerebral ischemia, what are the potential consequences to the brain?

A
  • Thinned cortex
  • Loss of brain mass (shrinks)
  • Liquifactive necrosis
    • tissue becomes very soft and falls apart
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9
Q

What is the typical cause of of hemorrhagic (red) infarcts?

A
  • Usually due to emboli + reperfusion
    • emboli composed of blood clot (heart/carotid) or of marrow/fat/tumor
    • something was plugging vessel then dislodged and blood poured out of it
  • Usually in MCA at branch points
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10
Q

What is the morphologic appearance of hemorrhagic (red) infarcts?

A
  • Gross
    • Punctate hemorrhages or big hematomas
    • Eventual resolution and cavitation
  • Microscopic (extravasated blood)
    • red neurons
    • edema
    • swollen astrocytes
    • lots of neutrophils
    • less neutrophils, then more macrophages
    • gliosis begins
    • even more macrophages
    • dense gliosis & new capillaries
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11
Q

What is the typical cause of ischemic (pale) infarcts?

A
  • Usually due to thrombi
    • often arise from atherosclerotic plaques
  • Usually at carotid bifurcation, MCA origin, or ends of basilar artery
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12
Q

What is the morphologic appearance of ischemic (pale) infarcts?

A
  • Gross appearance
    • First two days: pale, edema, wet
    • 2-10 days: gelatinous, outlines of infarct visible
    • 10-21 days: liquefaction and cavitation
  • Microscopic
    • red neurons
    • edema
    • swollen astrocytes
    • lots of neutrophils
    • less neutrophils, then more macrophages
    • gliosis begins
    • even more macrophages
    • dense gliosis & new capillaries
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13
Q

What brain findings may be seen in patients with hypertension?

A
  • Lacunar infarcts
    • deep vessels supplying basal ganglia, deep white matter, and brain stem
    • develop arteriolar sclerosis –> can become occluded
    • vessels become thicker due to increased tension
    • tissue loss with macrophages, gliosis
  • Slit hemorrhages
    • hypertension causes rupture of little penetrating vessels
    • over time, hemorrhages resorb leaving a brownish, slit-like cavity
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14
Q

What are the clinical features of intraparenchymal hemorrhage?

A
  • peak age = 60, high mortality
  • usually due to rupture of a small intraparenchymal vessel
  • can be “ganglionic” or “lobar”
  • Most common cause = hypertension
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15
Q

What are the predisposing causes of intraparenchymal hemorrhage?

A
  • Hypertension causes:
    • accelerated atherosclerosis
    • hyaline arteriolosclerosis
    • even frank necrosis
    • vessel walls are weaker
    • sometime see tiny aneurysms
      • Charcot-Bouchard microaneurysms = outpouching of vessel wall
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16
Q

What are the clinical features of subarachnoid hemorrhage?

A
  • Severe headache (“worst ever”)
  • Loss of consciousness in minutes
  • Death in 25-50%
  • If survive, regain consciousness
  • At risk for vasospastic injury, communicating hydrocephalus
17
Q

What are the predisposing causes of subarachnoid hemorrhage?

A
  • Berry aneurysm
    • thin walled sac with fragmented media
    • unknown etiology, most sporadic
    • ​Smoking
    • hypertension present in half of patients
    • grow slowly (when >1cm 50% risk of bleeding per year)
    • most common at arterial branch points
    • high mortality when ruptured
18
Q

What are the clinical features of Alzheimer disease?

A
  • Main symptom = dementia
    • early on forgetfulness, mood/behavior changes
    • later disorientation, memory loss, aphasia, loss of motor skills
  • Prognosis = 3-20 years
    • in 5-10 years patient will be profoundly disabled, mute, immobile
  • Death usually from infection (pneumonia)
19
Q

What are the morphological findings in Alzheimer disease?

A
  • Major degenerative disease of the cortex
  • Gross: atrophy
  • Microscopic: plaques and tangles
    • neuritic plaques: Aß peptides forming amyloid plaques around neuron
    • neurofibrillary tangles: bundles of filaments IN neuron cytoplasm composed of tau, MAP2, & ubiquitin
    • neuronal loss and gliosis
    • cerebral amyloid angiopathy (amyloid in vessels)
20
Q

What is the pathogenesis of Alzheimer disease?

A
  • Main abnormality = deposition and accumulation of Aß peptides
    • Aß comes from abnormal processing of amyloid precursor protein
    • Aß accumulates, forms amyloid aggregates
    • Aggregates are neurotoxic and pro-inflammatory
    • Tau accumulation seems to be a secondary phenomenon
      • caused by abnormal Aß
21
Q

What are the clinical features of Pick disease?

A
  • “Frontotemporal lobar degeneration/dementia” = FTLD
    • fairly common cause of early-onset dementia (younger patients <60 yoa)
  • Personality and language changes preced memory loss
    • First: frontal lobe signs (personality changes) and temporal lobe signs (language disturbances)
    • Later: dementia
22
Q

What are the morphologic findings in Pick disease?

A
  • Severe atrophy of frontal and temporal lobes
    • can cause ex-vacuo hydrocephalus
  • Neuronal loss
  • Pick bodies containing tau protein
23
Q

What are the clinical features of Parkinson disease?

A
  • Main symptoms: tremor, rigidity, bradykinesia
  • Parkinsonism
    • diminished facial expression
    • stooped posture
    • slowness of voluntary movement
    • festinating gait (slow –> fast)
    • rigidity
    • “pill-rolling” tremor
  • Some patients have dementia
  • Autonomic and cognitive dysfunction common
  • Prognosis: slightly shortened life expectancy
24
Q

What are the morphologic findings in Parkinson disease?

A
  • Degeneration of neurons in substantia nigra
  • Gross: atrophy of substantia nigra
    • pallor of substantia nigra due to loss of pigmented neurons
  • Microscopic: Lewy bodies
25
Q

What is the pathogenesis of Parkinson disease?

A
  • 5 genes encoding totally different products known to be associated with PD
  • No unifying mechanism known
  • Maybe alpha-synuclein, maybe something else
  • Whatever the cause, the problem is degeneration of dopaminergic neurons
26
Q

What are the clinical features of amyotrophic lateral sclerosis (ALS)?

A
  • Rapidly progressive weakness, spasticity, dysphagia
    • Early: asymmetric hand weakness, arm/leg spasticity, twitching, slurred speech
    • Later: atrophy, fasciculations, creeping paralysis
    • Eventually respiratory muscles involved
  • Sensory and cognitive function are unaffected
  • Death within 2-3 years due to respiratory compromise (or infection)
27
Q

What are the morphologic findings in amyotrophic lateral sclerosis (ALS)?

A
  • Thin anterior roots of spinal cord
  • Degeneration of corticospinal tracts
  • Decrease in anterior horn neurons
  • Skeletal muscles atrophied
28
Q

What is the pathogenesis of ALS?

A
  • Cause of motor neuron degeneration not well understood
  • SOD is mutated in some inherited cases - but lack of detoxification doesn’t seem to be the cause
  • Bottom line: neuronal degeneration, often with toxic protein accumulation

Neuro B5 - WLB (19 decks)

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