Flashcards in 32. Diseases of Myelin Deck (58)
define Guillian Barre syndrome
myelin is attacked by the immune system
a few qualities of myelin?
INERT, cell membrane, functions as an insulator, can be antigenic (MS, Guillian-Barre)
what cells make myelin in the CNS?
what cells make myelin in the PNS?
general definition of leukodystrophies?
DYSmyelinating disease. the MYELIN itself is abnormal
myelin loss due to enzymatic deficiency, gene mutations, accum of toxins.
describe myelin as it is wrapped around an axon
very compact layering, cytoplasm has been squeezed out of inner rings. inner leaflets of membrane are touching each other
Olig cell in CNS: a few qualities?
metabolically active. each Oligo supports up to 20 segments of myelin.
with demyelination diseases, is the myelin itself normal or abnl?
pathological definition of MS?
IMMUNE ATTACK on oligos.
chronic inf disease of CNS, causing demyelination, death of Oligs, tissue damage.
a few variants of MS?
Charcot (classical), Marburg, Balo's, Devic's, Schilder's, Massive Demyelinating Lesions
typical epidemiology of relapsing-remitting MS?
women > men
onset in 20s
tissue affected in relapsing-remitting MS?
plaque of periventricular white matter
do plaques in MS follow a particular pattern?
no, random plaques. tend to be sharp-edged, can extend to grey matter. do not follow tracts, vessels, nT pathway. can be anywhere.
(later slides: maybe they do follow blood vessels: beads on a string?)
what happens to axons after demyelination?
what cells are in the MS plaque?
CD4+ T cells, macrophages
the 4 main clinical types of MS?
clinical course of relapsing-remitting MS?
neuro problems, then they resolve within a few weeks. but resolution is indication that inflammation is subsiding, not re-myelination.
clinical course of progressive types of MS?
people have neuro problems, and they don't improve functioning between attacks. more axonal damage is occuring.
relapsing-remitting is also called what?
Charcot (classic MS)
Schilder's type MS: characteistics?
large, bilateral demyelinating lesions. quick onset. white matter is melted away.
Balo's Concentric Sclerosis (MS): characteristics?
path: think HALOs. alternating layers of myelin loss and preserved/normal oligs. unusual pattern! like tree rings.
Acute Disseminated Encephalomyelitis (ADEM): a few points/characteristics?
NOT MS. etiology is post-infection.
fulminant (sudden/severe) perivenous demyelinating disease.
usually seen after a viral infection (vaccine, measles, rabies).
it will reverse after the acute attack
what bacterium is associated with ADEM?
campylobacter jejuni. disease has been known to develop after exposure to this. prevalent in China. CJ may cross-react with CNS myelin -> attack of myelin
why might the BBB fail after ADEM?
breakdown of vessels (ADEM is perivenous)
what does ADEM look like on pathology?
white-enhancement in white matter, wide dissemination. with myelin stain, may see PINK STREAKS on brainstem slices. remember follows vessels.
post-measles encephalitis: typical presentation?
post-infectious demyelinating, usually 2-7 days after initial rash. fever, depressed consciousness.
less common now due to measles vaccine
post-measles encephalitis: appearance of brain imaging?
ring-enhancing, (not sure what type of scan)
on T2-weighted, widespread edema or demyelination in entire subcortical white matter
begins as perivascular.
Acute Hemorrhagic Encephalomyelitis (Weston Hurst Dz): characteristics?
abrupt onset, progressing to seizures, motor signs and death in 1-5 days (due to brainstem herniation)
necrosis of vessels plus demyelination
Acute Hemorrhagic Encephalomyelitis (Weston Hurst Dz): inflammatory infiltrate contains what?
Tcells, macrophages, VASCULAR NECROSIS DUE TO NEUTROPHIL ATTACK OF VESSEL WALL