Path: Demyelinating Diseases Flashcards
Enzyme deficient in Metachromatic Leukodystrophy
Arylsulfatase-A
-causes myelin breakdown
Enzyme defective in Krabbe Disease
Beta-galactocerebrosidase
-galactocerebroside accumulates and is toxic to oligodendrocytes
Describe Adrenoleukodystrophy.
ALD is an X-linked disorder of the adrenal cortex where enzymes used to break down Very Long Chain Fatty Acids (VLCFA) are mutated. The accumulation of VLCFAs leads to demyelination of the nervous system.
Describe Alexander Disease.
Mutations in Glial Fibrillary Acidic Protein (GFAP) leads to formation of Rosenthal fibers in CNS. Psychomotor retardation, dementia, paralysis and eventual death occur.
What is the cause for Multiple Sclerosis?
Actual cause is unknown. Damage results from autoimmune attack on myelin that can be initiated by viral infection or vaccination.
What is unique about MS in relation to other demyelinating diseases?
It has a RELAPSING AND REMITTING COURSE!!!
How can MS lead to hydrocephalus?
Old MS plaques from previous attacks lead to scarring. If these scars form in the arachnoid granulations, they can be blocked preventing the reabsorption of CSF.
What is Devic Disease? In what population is this most common?
More destructive form of MS. Presents as a bilateral optic neuritis and can involve gray matter.
High prevalence in Asian populations.
What is the physiologic mechanism that causes Central Pontine Myelinolysis and what is the common clinical presentation?
Very common in alcoholics. Deficiency in sodium leads to hyponatremia and patients present with nausea, vomitting, headaches etc. When this is rapidly corrected with a hypertonic solution the disease results.
The main hypothesis is that the rapid water loss from the neurons and oligodendrocytes after the solution is administered causes a “shock” in the cells and causes them to die.
Patients present with dysphagia, quadriplegia
What is Marchiafava - Bigmani Disease?
Similar to Central Pontine Myelinolysis, however the corpus callosum and anterior commissure are affected.
Alcoholics are a risk factor.
What 3 conditions can results from a thiamine deficiency?
Vitamin B1 deficiency:
- Beriberi disease: cardiac failure
- Wernicke Encephalopathy: reversible psychoses and ophthalmoplegia
- Korsakoff syndrome: irreversible form of Wernicke (if it Wernicke is not treated) with memory disturbance
What are the major symptoms of Wernicke-Korsakoff syndrome?
- Can’t form new memories
- loss of muscle coordination
- abnormal eye movements
- diplopia and eye lid drooping
What causes Subacute Combined Degeneration of the Spinal Cord?
Deficiency in Vit. B12 leading to pernicious anemia and demyelination of the posterior columns and cortical spinal tracts.
