Myelin Diseases

Multiple Sclerosis
-chronic, autoimmune demyelinating disease
-immune response activates macrophages and their proteins
-neuro deficits separated in time
-white matter lesions
-MRI
-Uhthoff's sign
-Lhermitte's sign
-acute: mononuclear inflammatory cells, myelin breakdown, little astrogliosis, decrease in oligodendroglia, larger paler astrocytic nuclei
-chronic: decrease in inflammatory cells, complete demyelination and axonal loss, severe astrogliosis
-CSF: increased IgG, increased mononuclear cells, oligoclonal bands

Guillain-Barre Syndrome
-autoimmune demyelinating neuropathy
-ascending paralysis
-preceded by acute infection
-inflammation and demyelination
-loss of DTR
-decreased conduction velocity
-increased CSF protein

Leukodystrophies
-abnormal formation of stability of myelin
-progressive loss of cerebral function
-lysosomal or peroxisomal enzyme defects
1. Metachromatic Leukodystrophy
-defect in arylsulfatase-A --> accumulation of sulfatides
-lossof myelin and gliosis
-metachromasia
2. Krabbe's Disease (Globoid Cell Leukodystrophy)
-deficiency of galactocerebroside b-galactosidase --> galactosphingosine
-loss of myelin and oligodendrocytes
-globoid cells around blood vessels
3. Adrenoleukodystrophy
-mutation in ALD gene
-lack of catabolism of very long chain fatty acids
-elevated VLCFA in serum
-loss of myelin
-gliosis
-lymphocytic inflammation
4. Progressive Multifocal Leukoencephalopathy
-JC polyomavirus infects oligodendrocytes --> demyelination
-viral inclusions in nuclei
-foamy macrophages
-astrogliosis