Multiple sclerosis

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	Central nervous system	MRI of the brain	Myelin and nerve structure
Nerve supply to the pelvis

Multiple sclerosis is an autoimmune disease that affects the brain and spinal cord (central nervous system).

MS; Demyelinating disease

Multiple sclerosis (MS) affects women more than men. The disorder is most commonly diagnosed between ages 20 and 40, but can be seen at any age.

MS is caused by damage to the myelin sheath, the protective covering that surrounds nerve cells. When this nerve covering is damaged, nerve impulses are slowed down or stopped.

The nerve damage is caused by inflammation. Inflammation occurs when the body's own immune cells attack the nervous system. Repeated episodes of inflammation can occur along any area of the brain, optic nerve, and spinal cord.

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Researchers are not sure what triggers the inflammation. The most common theories point to a virus or genetic defect, or a combination of both. Geographic studies indicate there may be an environmental factor involved.

People with a family history of MS and those who live in a geographical area where MS is more common have a slightly higher risk of the disease.

Review Date: 08/05/2010
Reviewed By: David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. Previously reviewed by Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).