Multiple sclerosis (MS) is a disease of the central nervous system. It is a chronic condition that can be disabling.

There are several types of MS:

  • Relapsing-remitting MS —Symptoms suddenly reappear periodically. They last for a few weeks or months, then go back into remission (a period with no symptoms). Symptoms may get worse with each occurrence.
  • Primary progressive MS —Symptoms gradually worsen after symptoms first appear. Relapses and remissions usually do not occur.
  • Secondary progressive MS —After years of relapses and remissions, symptoms suddenly begin to progressively worsen.
  • Progressive relapsing MS —Symptoms gradually worsen after symptoms first appear. One or more relapses may also occur.

Nerve Fiber (Neuron)
Myelin Sheath Damage
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The immune system normally attacks viruses or bacteria that should not be in the body. With MS, a problem with the immune system causes it to attack healthy nerves. In particular, MS attacks the nerve fibers in the brain, spinal cord, and the nerves of the eye. The exact cause of these immune problems is unknown.

The following may contribute to the development of MS:

  • Viral or other infection
  • Genetic factors (heredity)
  • Environmental factors
  • Breaking down of parts of the nervous system