multiple%20sclerosis
MULTIPLE SCLEROSIS
Multiple sclerosis is an acquired, chronic, immune-mediated, inflammatory disease of the brain and the spinal cord characterized by the presence of multiple discrete areas of myelin loss within the CNS and subsequent axonal degeneration.
It affects more women than men; however, men are more likely to have a malignant clinical course.
A multiple sclerosis attack is usually characterized by any neurological disturbance with minimum 24 hours duration in the absence of fever or infection.

Multiple%20sclerosis Signs and Symptoms

Introduction

  • Multiple sclerosis is an acquired, chronic, immune-mediated, inflammatory disease of the brain and the spinal cord characterized by presence of multiple discrete areas of myelin loss within the central nervous system and subsequent axonal degeneration
  • A multiple sclerosis attack is usually characterized by any neurological disturbance listed below with minimum of 24 hours duration in the absence of fever or infection
    • Attack can be either current or historical
    • May occur 30 days between each attack

 

Epidemiology

  • An estimated 2-2.5 million people worldwide have multiple sclerosis
  • In temperate areas (eg United States of America, Canada, New Zealand and parts of Australia), prevalence of multiple sclerosis is >100-200/100,000
  • In tropical areas like in Asia, the prevalence of multiple sclerosis is <5/100,000
    • In China the reported prevalence is 1-2/100,000 while in Japan it is 7.7/100,000
    • In Malaysia, the prevalence is estimated at a range of 2-3/100,000
    • In India, the prevalence is 7.8/100,000
  • Worldwide, multiple sclerosis is more common in women ages 20-40 years old
    • Common among whites than blacks, although blacks appear to become disabled earlier, suggesting more destructive tissue injury in blacks
    • Female to male ratio varies from 2:1 to 3:8

Pathophysiology

  • As multiple sclerosis is an autoimmune disease, autoreactive T and B cells are activated in the periphery and trans-migrate to the blood-brain barrier triggering an autoimmune cascade which leads to damage of the myelin sheath and axons directly within the central nervous system 
  • Pathological hallmark of multiple sclerosis is the presence of plaques or lesions which are multiple discrete areas of demyelination in the central nervous system with affinity for the optic nerves, spinal cord, brainstem, cerebellum, juxtacortical, subcortical and periventricular white matter regions as well as the cortical grey matter
  • Multiple sclerosis is characterized by two phases which are the early predominantly inflammatory phase wherein relapses are common and a later more progressive neurodegenerative phase characterized by axonal loss
  • In early phase of  multiple sclerosis, there is demyelination with inflammation and relative axonal preservation though axon loss also occurs
  • Lesions evolve differently in the early stages than at the later stage of the disease
  • Histologically, there are evidence of inflammation, myelin breakdown, astrogliosis, oligodendrocyte injury, axonal loss and remyelination
  • In progressive multiple sclerosis, there are increasing axonal loss, neurodegeneration and failure of remyelination

Risk Factors

  • Risk factors include:
    • Genetics
    • Ethnicity
    • Sex
      • Affects more women than men; however, men are more likely to have a malignant clinical course
    • Migration and latitude
    • Environmental factors:
      • Not enough exposure to sunlight and ultraviolet radiation
      • Low serum level of 25-hydroxycholecalciferol
      • Infection of Epstein-Barr virus
      • Smoking

Signs and Symptoms

  • Fatigue
  • Nystagmus
  • Optic neuritis
  • Transverse myelitis
  • Internuclear ophthalmoplegia
  • Vertigo
  • Sensory loss
    • Usually in the lower extremities and trunk
  • Trigeminal neuralgia
  • Lhermitte’s sign
  • Weakness
  • Loss of balance
  • Increased deep tendon reflex
  • Spasticity
  • Bladder dysfunction
  • Sexual dysfunction
  • Constipation
  • Uhthoff phenomenon
  • Depression
  • Other clinical presentations include age of onset at <10 or >55 years, prominent fever/headache, impairment of consciousness, encephalopathy, cortical features (aphasia, cortical blindness, seizures), non-scotomatous field defect, sudden hearing loss, no dissemination in space or time
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