The central nervous system comprises nerve cells, or neurons, in the brain and spinal cord. A fatty product called myelin surrounds most nerves in the body. Myelin allows the nerves to send clear electrical impulses faster and more effectively along the neurons.

Multiple sclerosis (MS) is an autoimmune disorder, which means that the body’s immune system turns against itself. This autoimmune response causes the protective myelin coating, or myelin sheath, to become inflamed and eventually destroyed in various places along the central nervous system. This destruction of myelin is called demyelination. This destructive process keeps the neurons from sending effective nerve signals. The signals become slowed, garbled, or blocked, causing the symptoms of multiple sclerosis to develop.

Symptoms of MS are varied and depend on the location of the myelin damage. Common symptoms are loss of muscle coordination, impaired vision, numbness or tingling sensations in the arms or legs, fatigue, and incontinence.

This disease can be difficult to diagnose because the symptoms, which can last from days to months, may come and go without any pattern.