An autoimmune disease of the central nervous system (CNS). The effects of MS are often progressive; each relapse can cause plaque formations in the white matter covering the nervous tracts. This damage to the myelin sheath, which insulates the nerves, gives MS its debilitating symptoms by reducing the efficiency of nervous transduction. Over many years, the cumulative damage of MS can cause the loss of balance, muscle weaknesses and reduced cognitive abilities.

Above: MRI scan of the human head. MRI is often a key tool in the diagnosis of MS
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