24. Neuropathology of Degenerative Diseases Flashcards Preview

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Alzheimer's: location where it primarily presents in the brain? types of proteins involved?

neurofibrillary tangles (tau) and senile plaques (beta-amyloid)


Huntington's: location where it primarily affects the brain and types of proteins involved?

caudate/extrapyramidal motor system. Trinucleotide repeat disease. (proteins with abnormally expanded poly-glutamine repeats)


what is the extrapyramidal system?

part of the motor system, causes involuntary reflexes and movement, and modulation of movement (ie coordination). modulates/indirect control of anterior horn cells.
modulate motor activity without directly innervating motor neurons.


what is the pyramidal system? which pathways?

corticospinal and some corticobulbar tracts, directly innervate motor neurons of the spinal cord or brainstem.


Parkinson's: location where it primarily affects the brain? types of proteins involved?

Substantia nigra pars compacta


Huntingtons and Parkinson's can both progress from a motor disturbance to what?

both can eventually include dementia.


Amylotrophic Lateral Sclerosis (ALS) location in brain, proteins involved?

motor system (degeneration of both lower and upper)
selective degeneration of ventral roots
atrophy of grouped fiber types seen on biopsy (patchwork)


Alzheimer's is found with inc incidence around what age?

beginning at age 60


Alz: how do patients present?

memory loss (esp for memory of recent events), loss of initiave, difficulty in word finding and calculation, disorientation to time and place.


Alz: diagnosis?

no diag test: diagnostic efforts aimed ar ruling out other, treatable causes. Diag of exclusion


what are some reversible causes of dementia?

-metabolic disturbances
-infection (UTI, pneumonia)
-psychiatric (depression can present as Alz in the elderly)


Alz: appearance on gross pathology?

pan-lobar cortical atrophy (entire brain, with some sparing of the occipital lobes)


Alz: appearance of gross path on coronal section?

dilation of ventricles as a consequence of loss of brain parenchyma (hydrocephalus ex vacuo)


Alz: histology?

flame-shaped neurofibrillary tangle (tau)
spoltch-shaped plaque of beta-amyloid
These are both present in non-Alz brains, but are present in greater numbers with Alz. No cutoff number has been established.


Alz: loss of recent memory on presentation can progress to what?

personality problems that we associate with frontal lobe damage


Is biopsy used for dx of Alz?

would only be done to rule out something else. requires a big amount of tissue from the hippocampus, not generally done.


Alz: what is the deal with ApoE4?

part of the processing pathway of the Amyloid Precursor Protein: ApoE is involved in removing the gamma-secretase product from the brain: ApoE4 version of ApoE makes removal slower --> buildup and neurotoxicity


General: treatment for Alz?

acetylcholine esterase inhibitor (donepazil)
NMDA receptor antagonist (memantine)


what are the 2 versions of Tau to be concerned about?

Tau with 3-repeat and Tau with 4-repeat. some diseases have more of one type or the other, can be helpful in diagnosis?


Pick's disease: gross brain appearance?

profound frontotemporal corctical atrophy. less extensive than Alz (no parietal, less temporal lobe involvement)
(The disease PICKs the front of the brain)


Pick's disease histology: what do pick cells look like?

large swollen neurons in the affected cortex. balloon cytoplasm. full of Tau protein


Parkinson's disease should respond to what medication?

Sinemet: (combination of carbidopa and levodopa)


Park: clinical triad?

tremor, bradykinesia, rigidity
(better to remember TRAP: tremor, rigidity, ataxia/bradykinesia, postural instability)


Park: pt appearance at onset?

acryonym: TRAP (tremor, rigidity, akinesia, postural instability)
unilateral tremor, less movement, stiffness. pill rolling tremor at REST, shuffling posture, loss of affect in face.


what is meant by rigidity in Park?

difficulty initiating movement, cog-wheeling (initial resistance, then sudden give)


Park: degeneration where?

degen of substantial nigra (loss of pigment) and locus ceruleus


Park: classic histo finding?

Lewy bodies (nearly round very pink cytoplasmic inclusion). accumulation of synuclein.


how can we distinguish between parkinson's disease and another disease with parkinsonism as a feature?

response to Sinemet (carbidopa/levodopa)


ALS: classic presentation?

wasting due to lower motor neuron involvement, and hyper-reflexia in lower extremities due to upper motor neuron involvement


Huntington's: age of onset?