17.6 Demyelinating Disorders Flashcards
What are the cells that make myelin in the CNS?
Oligodendrocytes
What are the cells that make myelin in the PNS?
Schwann Cells
Demyelinating Disorders
Destruction of the myelin or oligodendrocytes that preserves the axons but will have impaired conduction of the impulse.
Leukodystrophies
Inherited mutation in enzymes involved in the production and maintenance of myelin
Metachromatic Leukodystrophy
Deficiency of arylsulfatase - myelin cannot be degraded and accumulates in lysosomes
What is the most common type of leukodystrophy?
Metachromatic Leukodystrophy
Krabbe Disease
Deficiency of galactocerebroside ß-galactosidase leading to the accumulation of galactocerebroside in macrophages
Adrenoleukodystrophy
Impaired addition of coenzyme A to long chain fatty acids that lead to the accumulation of FAs and damage of adrenal gland and white matter.
Multiple Sclerosis
Autoimmune destruction of CNS myelin AND oligodendrocytes
What mutation is MS associated with?
HLA-DR2
What regions is MS more commonly seen in?
Regions away from the equator
What gender is more commonly affected by MS?
Females
What are the clinical features of MS?
- Blurring of vision in one eye
- Vertigo and scanning speech
- Internuclear ophthalmoplegia (MLF)
How does internuclear ophthalmoplegia occur with the involvement of the MLF?
MLF damage prevents input from CN VI to CN III to contract the medial rectus in horizontal gazing.
What does lumbar puncture of MS show?
- Lymphocytes
- Oligoclonal IgG bands
- Myelin basic protein
What is the treatment of MS?
Steroids and interferon-ß which slows the progression of the disease.
Subacute Sclerosis Panencephalitis
Progressive and debilitating encephalitis that leads to death from the slow infection of the brain by the measles virus.
What matter of the brain does Subacute Sclerosis Panencephalitis involve?
BOTH the gray and the white matter
Progressive Multifocal Leukoencephalopathy
JC virus infection of the oligodendrocytes that is reactivated with immunosuppression that leads to neurological signs and death.
Central Pontine Myelinolysis
Focal demyelination of the pons
What is the cause of central pontine myelinolysis?
Due to rapid IV correction of hyponatremia and is found in malnourished patients
What is the classic presentation of central pontine myelinolysis?
Acute Paralysis (Locked In Syndrome)
