Diseases of White Matter Flashcards
what is secondary loss of myelin?
when an axon dies, the surrounding myelin will die off as well
what are the two types of demyelinating disorders?
leukodystrophies (dysmyelinating)
myelinoclastic group
what is the pathogenesis of a leukodystrophy?
metabolic derangement affecting proteins that keep myelin alive
what is the pathogenesis of a myelinoclastic process?
myelin is under attack
are axons spared in demyelinating disorders?
yes
what are the four most common leukodystrophies?
Krabbe, adrenoleukodystrophy, adrenomyeloneuropathy, metachromatic leukodystrophy
what is the age of onset, inheritance pattern and protein defect in Krabbe disease?
infants and children, AR, galactocerebroside-beta-galactosidase
what is the age of onset, inheritance pattern and protein defect in adrenoleukodystrophy and adrenomyeloneuropathy?
young/old, XLR (except infantile form of ALD, which is AR), ABCD1
what is the age of onset, inheritance pattern and protein affected for metachormatic leukodystrophy?
all ages, AR, arylsulftase A
describe the characteristic gross pathological changes in leukodystrophies
widespread and confluent demyelination with sparing of the U-fibers (low metabolic turnover)
how are most leukodystrophies diagnosed?
via biochemical analysis
what are the two types of myelinoclastic disorders that we need to know?
multiple sclerosis
parainfectious disorders
what is the epidemiology of MS?
attacks young to middle aged, 2:1 F:M
lesions of MS have what character?
distributed over time and space
attacks of demyelination follow what time course?
they are remitting and relapsing (i.e. they come and go)
what are the gross characteristics of MS plaques?
they are sharply demarcated, asymmetrical, widespread
histologically what cells are present in MS plaques acutely?
lymphocytes and histiocytes in the perivenular region
histologically what cells are present in MS plaques chronically?
astrocytes, hence they are gliotic
what is understood about the pathogenesis of MS?
CD4 cells react against myelin basic protein; macrophages are responsible for the actual demyelination
CD8 cells are present
what are the genetic factors in play with MS?
HLA-DR2
also, first degree relatives are at 15 fold greater risk
what lab tests are available for MS?
MBP in the CSF (not major basic protein, myelin basic protein)
IgG in CSF
oligoclonal bands of Ig in CSF
what are parainfectious disorders?
autoimmune response against an infectious agent pathologically targets myelin
what is the histological change present in parainfectious disorders?
perivenular demyelination with chronic inflammation
