17.6 Demyelinating Disorders

Question 1

What are the cells that make myelin in the CNS?

Answer 1

Oligodendrocytes

Question 2

What are the cells that make myelin in the PNS?

Answer 2

Schwann Cells

Question 3

Demyelinating Disorders

Answer 3

Destruction of the myelin or oligodendrocytes that preserves the axons but will have impaired conduction of the impulse.

Question 4

Leukodystrophies

Answer 4

Inherited mutation in enzymes involved in the production and maintenance of myelin

Question 5

Metachromatic Leukodystrophy

Answer 5

Deficiency of arylsulfatase - myelin cannot be degraded and accumulates in lysosomes

Question 6

What is the most common type of leukodystrophy?

Answer 6

Metachromatic Leukodystrophy

Question 7

Krabbe Disease

Answer 7

Deficiency of galactocerebroside ß-galactosidase leading to the accumulation of galactocerebroside in macrophages

Question 8

Adrenoleukodystrophy

Answer 8

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.

Question 9

Multiple Sclerosis

Answer 9

Autoimmune destruction of CNS myelin AND oligodendrocytes

Question 10

What mutation is MS associated with?

Answer 10

HLA-DR2

Question 11

What regions is MS more commonly seen in?

Answer 11

Regions away from the equator

Question 12

What gender is more commonly affected by MS?

Answer 12

Females

Question 13

What are the clinical features of MS?

Answer 13

• Blurring of vision in one eye
• Vertigo and scanning speech
• Internuclear ophthalmoplegia (MLF)

Question 14

How does internuclear ophthalmoplegia occur with the involvement of the MLF?

Answer 14

MLF damage prevents input from CN VI to CN III to contract the medial rectus in horizontal gazing.

Question 15

What does lumbar puncture of MS show?

Answer 15

• Lymphocytes
• Oligoclonal IgG bands
• Myelin basic protein

Question 16

What is the treatment of MS?

Answer 16

Steroids and interferon-ß which slows the progression of the disease.

Question 17

Subacute Sclerosis Panencephalitis

Answer 17

Progressive and debilitating encephalitis that leads to death from the slow infection of the brain by the measles virus.

Question 18

What matter of the brain does Subacute Sclerosis Panencephalitis involve?

Answer 18

BOTH the gray and the white matter

Question 19

Progressive Multifocal Leukoencephalopathy

Answer 19

JC virus infection of the oligodendrocytes that is reactivated with immunosuppression that leads to neurological signs and death.

Question 20

Central Pontine Myelinolysis

Answer 20

Focal demyelination of the pons

Question 21

What is the cause of central pontine myelinolysis?

Answer 21

Due to rapid IV correction of hyponatremia and is found in malnourished patients

Question 22

What is the classic presentation of central pontine myelinolysis?

Answer 22

Acute Paralysis (Locked In Syndrome)