Myelin Pathology Flashcards
Active vs. Inactive MS plaques
active: hypercellular w/ macrophages and lymphocytic inflammation. Mostly T cells. Macrophages may contain myelin inside.
Inactive: hypocellular w/ loss of oligos and fibrillary gliosis.
Marburg MS
Acute, rapidly progressive MS. Death within a few months to 1 yr. No fever or meningeal signs. Histology resembles that of an active plaque
Neuromyelitis optica/Devic disease
optic neuritis and acute transverse meylitis separated by wks. Many die in acute phase.
Transverse myelitis gives UMN signs and spinal cord level
spinal cord may be partly necrotic
pathophysiology distinct from MS: autoimmune attack of aquaporin 4 channels of astrocytes –> breakdown of the BBB.
Balo concenctric sclerosis
plaques in circumferential bands of myelin loss alternating with rings of myelin preservation. monophasic and rapidly progressive.
Acute disseminated encephalomyelitis
multifocal inflammatory disease of T-cell mediated hypersensitivity.
often preceded by viral infection or, rarely, vaccination
80% recovery
symptoms include fever (and headache, vomiting, sensory loss, ataxia etc)
inflammatory infiltrate around small veins extending into the parenchyma. may involve leptomeninges or sp cord
small numberous, periventricular lesions
Impaired consciousness seen in ADEM but NOT in MS
Acute hemorrhagic leukoencephalitis
hyperactue ADEM. usually fatal
small blood vessels show fibrinoid necrosis, demyelination, and perivascular hemorrhage.
association with ulcerative colitis and Chron’s disease
Progressive multifocal leukoencephalopathy
caused by JC virus in ppl with impaired T-cell mediated immunity (HIV/AIDS)
small grey discoloration of white matter
scanty lympohcytes in association w macrophages, demyelination, and bizarre astrocytes
with HAART you may get immune reconstitution: intense inflammation
oligos may show homogenous intranuclear viral inclusions
Subacute sclerosing panencephalitis
viral. seen years after measles infection. significantly reduced by vaccination
may lead to death
Characteristics of leukodystrophies
inherited metabolic disorders leading to defects in myelin production, maintenance, turnover, or metabolism. progressive course with death 6 mo to 3 yrs post onset. shows diffuse demyelination of white matter with sparing of arcuate fibers (U fibers). widened sulci and big ventricles
adenoleukodystrophy
X linked
accumulation of VLCFAs
metachromatic leukodystrophy
infancy with motor disability
aryl sulfatase A
Globoid cell leukodystrophy
Krabbe’s disease
galactocerebroside-Betat-galactosidase deficiency leads to too much galactosyl sphingosine, which kills oligos
see MULTINUCLEATED MACROPHAGES
Spongiform leukodystrophy
seen in infancy with macrocephaly, hypotonia, blindness, and spasticity
aspartocyclase deficiency
spongy white matter with Alzheimer type II astrocytes
Alexander disease/ dysmyelinogenic leukodystrophy
macrocephaly, GFAF mutation, and rosenthal fibers
Central pontine myelinolysis
complication of rapid overcorrection of electrolyte imbalance, esp. hyponatremia
seen in malnourished and alcoholics
symmetrical areas of meylin loss in the midline of the basis pontis. lesions elsewhere also seen
Marchiafava-Bignami Disease
due to vitamin deficiency?
thinning and discoloration of the corpus callosum
Subacute combined degeneration
due to vitamin B12 deficiency
can be seen in spinal cord and peripheral nerves too
symmetric degeneration of the thoracic cord initially in posterior columns; later in corticospinal and spinocerebellar tracts of lateral columns.
