Central Nervous System 5. Demyelinating Diseases MC

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Central Nervous System5. Demyelinating Diseases
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Multiple Sclerosis

• MC demyelinating disease
• Prevalence 11000 in USA Europe
• More prevalent in the Northern Southern
  temperate zones than in the tropics or subtropics
  (areas away from the equator)
• Individuals take on the relative risk of the
  environment in which they spent their first 15
  years possible exposure to Virus
• Affects white young adults (15-50, mean 30
  yrs.), F/M 2/1
• A chronic relapsing remitting disease
• Episodes of neurologic deficits over days or
  weeks
• Followed by partial remission.
• After each attack some permanent sequelae remain
• MC symptoms are
• ? vision (usually unilateral), Diplopia
  vertigo, ataxia,
• ? sensation muscular weakness with Spasticity
• ? sphincter control (possible incontinence)
  emotional lability

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Multiple Sclerosis

• Gross
• Hallmark of MS is Plaque
• A relatively firm well-circumscribed reactive
  gliosis
• Area of dark discoloration in the white matter
• Dark b/c of complete loss of myelin
• Frequently involve the periventricular white
  matter (corona radiata), optic nerves chiasm
  (hot spots areas of demyelization )
• Randomly scattered throughout the cerebrum,
  cerebellum, brainstem spinal cord.
• Microscopic
• Active plaques
• Edema, infiltration by lymphocytes monocytes,
  myelin breakdown with lipid-laden macrophages
  phagocytize myelin
• Some ? in oligodendroglia with preservation of
  neuronal axons.
• Inactive plaques (chronic)
• Myelin loss, dense gliosis
• ? oligodendroglia secondary loss of axons due
  to ? gliosis which tend to compress the axons

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Multiple Sclerosis
Arrows MS plaques in white matter Colored like
gray matter ? darker b/c have total loss of
myelin
Myelinated axons
MS plaques very well circumscribed
Myelin stain (stains myelin blue) Pink MS
plaques in, demyelization periventricular white
matter complete loss of myelin
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Multiple Sclerosis

• Etiology Multifactorial
• Environmental factors
• Infectious agent (virus) ? , JC virus ?
• Where lived in 1st 15 years of life
• Genetic factors
• Familial predisposition, association with HLA-DR2
• 1st degree relatives of MS patients have 15X ?
  risk of developing MS
• Immune factors
• Experimental allergic encephalitis
• ? levels of oligoclonal immunoglobulins in CSF
• Fair response to steroid therapy
• Prognosis
• Most MS patients survive 20 - 30 yrs after the
  onset of Symptoms bed ridden, usually die with
  infection UTI sepsis or pneumonia