A person with multiple sclerosis has inflammation of the brain and spinal cord that weakens the nervous system.

The exact cause for multiple sclerosis is not known. The immune system mistakenly destroys the lining that covers nerves, called myelin. This causes the nerves in the brain and spinal cord to malfunction.

The severity of multiple sclerosis varies from person to person. About 70 percent of people with multiple sclerosis lead active, productive lives.