Path- 1: Neuro/cytology Flashcards
What happens to the Schwann cells in segmental demyelination?
They have either a disfxn (in hereditary motor or sensory neuropathy) or damage (like in Guillian Barre)
What happens to the axons in segmental demyelination?
NOTHING
What do you see on a microscope with chronic de- and remyelination?
Onion bulbs
“Pissed off shrek in plastic wrap.”
Which cells are absolutely ESSENTIAL for the regeneration of the injured PNS?
Schwann cells
What is the pattern of demyelinatiopn in multifocal motor neuropathy?
Segmental demyelination of a motor axon
In axonal degeneration and muscle atrophy, what happens first and second?
There is primary destruction of the axon and a secondary loss of the myelin sheath.
Define: This is a bundle of muscle fibers that lose innervation from a nerve, so they become small and angular.
Grouped atrophy
What is the process called when there is axonal injury due to transection?
Wallerian dgeneration
What happens in wallerian degeneration at the distal portion of the nerve?
axon breaks down within a day –> Schwann cells begin to destroy myelin and engulf axon fragements –> macrophages FEAST
What happens in wallerian degeneration at the proximal portion of the nerve?
there is degeneration for only 2 or 3 distal internodes, undergoes regenerative activity
What happens to the muscle in axonal transections?
Atrophy
What forms on the nerve “stump” as far as the reinervation process?
It forms clusters of small axons with thin myelin
Define: this is a benign, encapsulated neoplasm that has neoplastic proliferation in the endoneurium with the perineurium forming the capsule. Typically forms around VIII.
Schwannoma
What are the clinical Sx of Guillian Barre?
Can cause resp arrest, ascending paralysis, segmental demyelination of the spinal and peripheral nerves (primary lesion)
it’s like when Neo sticks his hand in that mirror and that mirror shit climbs up his body and then down his troat. Crazayyyy
What causes Guillian Barre?
immune mediated response due to infection of Capylobacter jejune, CMV, mycoplasma pneumo or vaccines.
Is nerve conduction velocity increased or decreased in Guillian Barre?
Decreased
Is CSF protein increased or decreased in Guillian Barre?
increased
What causes HMSN’s?
mutations in genes involved in peripheral nerve function
What is the most femousestestest type I HMSN?
Charcot Marie Tooth
Who does CMT affect?
KIDS or young adults
What is the inheritance of CMT?
AD
What is the clinical presentation of CMT?
Progressive paralysis below knee (peronial muscular atrophy), sensorimotor deficit with orthopedic deficit such as pes cavus, notmal life span
What type of HMSN of Dejerine Sottas?
HMSN tpye III
Where in the doby does Dejerine Sottas affect?
both the trunk and the limb muscles
What is the inheritance of Dejerine Sottas?
AR
What is the clinical presentation of Dejerine Sottas?
infintile onset (1-12mo), large peripheral nerves, demyelination w/onion (skrek) bulbing, more severe than CMT
What are the suspected causes of peripheral neuopathies in diabetes tpye 2?
Polyol pathway and non-enzymatic glycosylation
What is the clinical presentation of peripheral neuopathy in DM type 2?
most common symmetiric neuropathy involving both sensory and motor nerves, decreased sensation in the distal extremtiies, decreased paiin –> ulcers, ANS dysfxn (including NO BONERS OH NOOOOOOOOOOOOOOOOOO)
Tumors usually cause what types of dysfxns with nerves?
Compression
What process is Lambert-Eaton syndrome assocaited with?
paraneoplastic process, 60% of the time it’s small cell CA of the lung
What are the Sx of LES?
proximal muscle weakness w/autonomic dysfxn
Does LES pt’s repsond to anti-AchE’s? Why?
NO. this is an autoimmunity to Ca++ channels, not to the Ach channels (like in MG).
Is there an increase or decrease in nerve conduction with repetitive stimualtion?
Increase (you’re allowing more Ca++ to enter the presynaptic terminal)
What are traumatic neuromas?
They’re misaligned or tangles segments that occur in a random fashion after attemped nerve REGENERATION post-truama
Though neurons vary in size/shape/structure, what 4 things do all neurons have?
Microtubules, neurofilaments, golgi, and rER
Do mature neurons divide?
No
Since mature neurons dont divide, what does this mean clinically?
Lose neurons with age, neurons do not regenerate over long distances in the CNS, infarcts that transect the internal capsule –> permanent motor deficits
What are Nissl bodies?
rER basophilic granules in the cytopasm of the neuron
What is neuromelanin?
Some neurons of the substantia nigra, the locus ceruleus, dorsal motor nucleus of X, and median raphe nucleus contain dark pigment
What are the 2 changes in chomatolysis in response to neuronal injury?
- cytoplasm expands and Nissle substances disperse near the plasma membrane
- Nucleus becomes eccentric (like oh shit oh shit oh shit)
What happens in neuonophagia?
Injuries that kill neurons create debris and elicit phagocytosis by microglial cells
Microglia are like small sharks feeding off a dying whale. This makes me sad. DYING WHALES IS HORRIBLE
What are the signs of atrophied neurons (Creutzfeld-Jacob disease)?
Neurons shrivel and become hyperchomatic
What bug causes intranuclear inclusions with prominent clear halos?
CMV
Which bug causes cytoplasmic “negri bodies” which resemble RBC’s?
Rabies
Which pt’s have Lewy bodies?
Parkinsons pts
Which infections cause Cowdry bodies?
Herpes
Astrocytes contain which important staining marker?
GFAP
What is the response of astrocytes to trauma?
Proliferate locally (astrocytosis or reactive gliosis)
Astrocytosis is the most important histopathologic indicator of what?
CNS injury
What is the result of astrocytosis?
Glial scar
What are the characteristics to astrocytosis?
hypertrophy, hyperplasia, cytoplasm stains bright pink (gemistocytic astrocytes).
Long stanging gliosis associated with rosenthal fibers are associeted with what?
Cerebellar pilocytic astrocytoma
What is it called when astrocytes undergo neoplastic transformation resulting ina tumor?
Astrocytosis/glioma
What are corpora amylacea?
5-50 micrometer basophils and amorphous structes which accumulate with normal agins int eh subpial and subependymal regions, represent degenerative change in astrocytes
Alzheimer type II astrocytes occur in which pts?
pts with long standing hyperammonia, wilsons or hereditary metabolic diseases of the urea cycle
What are the fxns of glia/astrocytes?
act as BBB, metabolic buffers, repair and scar formation
What are the fxns of oligodendrocytes?
myelination of multiple axons
What is the fxn of ependymal cells?
Line CSF-filled spaces, regulate CSF transport
Some viral infections target ependymal cells during gestation which may result in what condition?
Hydrocephalus
Where are ependymomas?
tumors usually in the ventricles but can appear in spinal cord
What is the main fxn of microglia?
macrophages of the CNS which proliferate after injury
What types of injuries cause red neurons to ARISE?
Acute CNS hypoxia/ischemia
think red neurons –> red blood
What are the characteritics of red neurons?
cell body atrophy, pyknosis of the nucleus, loss of Nissl substance, and intense eosinophilia of the cytoplasm
When are the subacute and chronic degeneration of neurons seen?
In necrosis/progressive disease, seen early as reactive gliosis, lasts 2 weeks and longer
What are axonal reactions?
they’re just the axonal regeneration, increased protein sysnthesis
