Multiple sclerosis (MS) is a chronic autoimmune disease in which the body attacks proteins in the myelin sheath, a fatty substance that insulates nerve fibers in the brain and spinal cord. Damage to the sheaths—and then to the fibers that they surround—causes scarring and blocks nerve signals that control muscle coordination, sensation, and vision.

An estimated 300,000 people in the United States have MS, and two-thirds of those are women. Most people experience their first symptoms—which include numbness, tingling, or weakness in limbs; pain during eye movement; or electric shock sensations that occur during head movements—in early adulthood. Genetic factors play a small role in the development of MS, but researchers believe that most cases are brought on by viruses or prolonged periods of sickness.

The disease occurs in four main patterns: people with relapsing remitting MS may experience long periods without symptoms punctuated by abrupt relapses. Many people with this variety will eventually develop secondary progressive MS, in which those symptoms become permanent. Less common is primary progressive MS, which usually appears in people older than 40. People with this version of the disease do not experience intermittent symptoms, but instead a gradual deterioration. When these symptoms are coupled with periods when symptoms intensify, it is known as progressive relapsing MS.

There are no specific tests for MS, although MRI scans may reveal lesions in the brain or spinal cord caused by myelin loss. An injected dye can highlight lesions that have formed within the past 2 months, which may help a doctor decide whether the MS is in an active phase.

Medications for early stage MS include beta interferons—genetically engineered proteins that help regulate the immune system—and corticosteroids to fight inflammation. Regular exercise and physical therapy can help patients strengthen their muscles and continue to live independently, often with the use of a cane, wheelchair, or mobility scooter. The worst cases of MS can progress so far that a person can no longer write, speak, or walk, but the majority of cases can be controlled with medications and lifestyle modifications.

ADDITIONAL FACTS

  1. One complementary treatment for MS is plasma exchange, in which blood is removed from the patient, blood cells are separated and mixed with a replacement solution, and the mixture is returned to the body. Plasma exchange may dilute the concentration of destructive antibodies, although it has no proven benefit if performed more than 3 months after symptoms first appear.
  2. Many people with MS experience muscle weakening on extremely hot days or in hot showers or baths. Cooling down for a few hours in an air-conditioned room or a tepid bath may provide relief.
  3. Many viruses and bacteria—including the Epstein-Barr virus, which also causes mononucleosis—have been suspected of causing MS, but none has been shown to be causative so far.