Demylenating Disorders Flashcards
What are leukodystrophies?
Inherited mutations in enzymes necessary for production or maintenance of myelin.
Which cells myelinates the CNS? The PNS?whwt happens to axons during demyelination disorders?
Oligodendrocytes myelinate the CNS and Schwann cells myelinate the PNS. Axons are generally preserved.
What are metachromatic leukodystrophies and what is the inheritance type?
Autosomal recessive disorder due to a deficiency of arylsulfatase. Sulfatides cannot be degraded and accumulated the lysosomes of oligodendrocytes (lysosomal storage disease).
What is Krabbe disease and how is it inherited?
Autosomal recessive deficiency of galactocerebrosidase which leads to the accumulation of galactocerebroside.
What is adrenoleukodystrophy and how is it inherited? Symptoms?
X linked defect due to impaired addition of coenzyme A to long chain fatty acids which damage adrenal glands and white matter of the brain. Symptoms include dementia, poor coordination, seizures, hyperactivity.
What is multiple sclerosis? What is associated with? Which regions of the world is it common in?
Autoimmune destruction of CNS myelin and oligodendrocytes. Most common in women and also most common chronic CNS disease of young adults. Associated with HLA-DR2, in regions away from the equator.
How is multiple sclerosis diagnosed and treated?
MRI reveals plaques which are areas of white matter demyelination. Lumbar puncture shows increased lymphocytes, increased immunoglobulins with oligoclonal IgG bands on high resolution electrophoresis and myelin basic protein.
Gross exam shows gray appearing plaques in the white matter.
Tx of acute attacks is with high dose steroids. Long term treatment is with interferon beta to slow disease progression.
A 37 year old teacher presents to your office with a complaint of blurry vision in her left eye. During the interview, she appears to be intoxicated when she is speaking. She pauses between words. Neuro exam shows she has lost sensation on her left side and she has weakness on her lower extremities. What does she have? What other problems would you expect her to have in terms of Genitourinary and visual defects?
She has multiple sclerosis. Other issues with bowel, bladder and equal dysfunction. She also might have inter nuclear opthalmoplegia due to medial longitudinal fasiculus damage.
What brain disorder does measles virus cause? When does it occur and when do symptoms show up? What is visible when you look at neurons?
Measles virus causes subacute sclerosing panencephalitis which is a progressive, debilitating encephalitis leading to death. Infection occurs in infancy. Neurologic signs arise years later during childhood. Characterized by viral inclusions within neurons (gray matter) and oligodendrocytes (white matter).
What is progressive multifocal leukoencephalopathy? How does it present?
It is caused by JC virus infection of oligodendrocytes due to immunosupression. Presents with rapidly progressing neurologic signs (visual loss, weakness, dementia) leading to death.
A patient presents with acute bilateral paralysis. He looks like he is locked in his body. What is on your ddx? What causes it?
He has central pontine myelinolysis which is a focal demyelination of the pins. This is due to rapid intravenous correction of hyponatremia which occurs in severely malnourished patients (e.g. Alcoholics and patients with liver disease).
