SDL: Diseases of White Matter Flashcards
myelin damage with relative preservation of axons; what causes this?
myelin loss; autoimmune attack, infection, hypoxic-ischemic injury, trauma
loss of previously-formed and intact myelin due to a specific problem destroying it, such as MS and related conditions
demyelination
demyelination includes preservation of…
axons, although eventually without their myelin sheaths they degenerate (secondary damage to axons)
diseases where myelin is defective from the start and either cannot be produced or maintained appropriately
dysmyelinating diseases (leukodystrophies)
diseases with indirect damage to myelin
HIV leukoencephalopathy, progressive multifocal leukoencephalopathy, carbon monoxide poisoning
most common demyelinating disorder; gender ratio of affected
multiple sclerosis; M:F=1:2
Clinical findings of MS
random “attacks” of blurred vision, paresthesia, weakness; findings do not fit into a definitive anatomical distribution
MS is usually common in what areas of the world?
N. Europe and the US (rare in orientals)
autoimmune aspect of MS
mainly CD4 and CD8 T-cells and macrophages
the pathology behind the acute phase of MS
inflammatory cells emigrate from the blood vessels, attack myelin sheaths, resulting in demyelination. axons are initially intact.
pathology of chronic MS lesion
inflammation subsides, reactive astrocytosis, some axons degenerated, new myelin is forming on others
most common locations for MS manifestation and their clinical signs
optic nerve (unilateral vision impairment), spinal cord (motor/sensory impairment, bladder control problems), brain stem (cranial nerve defects, ataxia)
diagnostic tool for MS lesions
MRI, CSF electrophoresis to look for increased Ig’s and oligoclonal bands
MS plaques on cross section of the rain are characterized as..
irregular tan-grey lesions randomly distributed in the white matter, typically deep and in some connection to the ventricular surface.
pathology of acute MS vs chronic MS
acute has many inflammatory cells and myelin breakdown, but not much astrocytosis, so it appears soft and shiny. chronic has a dull appearance, is firm, because the inflammation has subsided and astrocytosis took place
vairants of MS
Marburg type (death in 1-6 mons), balo type (death in 2 yrs), shilder type (predom in children)
another name for devic disease
neuromyelitis optica (involved the optic nerve and spinal cord)
symptoms/signs of devic disease
synchronous blindness and paraplegia; autoantibodies to aquaporin-4 receptors
acute disseminated encephalomyelitis seen post..//this suggests what?
post infection, perivenous, post vaccine (suggesting a cross reaction with and autoimmunity against myelin)
gross pathology of ANHE
numerous petechiae in white matter
other primary demyelinating diseases
central pontine and extrapontine myelinosis (osmotic demyelination syndrome); marchiafava-bignami; demyelinating pseudotumor
typical lesion of osmotic demylination/central pontine myelinosis
demyelinating lesion in the center of base of pons
main culprit of osmotic demyelination/central pontine myelinosis
rapid CORRECTION of hyponatremia (electrolyte imbalance)
neuroimaging aspect of demyelinating pseudotumor
an incomplete, C-shaped ring enhancement pattern which may look like a neoplasm. the opening of the incomplete ring opens toward the ventricle side.
a viral infection of oligodendrocytes, interfering with their myelin-forming function
progressive multifocal leukoencephalopathy (usually in HIV pos patients
