“In multiple sclerosis (MS), damage to the myelin coating around the nerve fibers in the central nervous system (CNS) and to the nerve fibers themselves interferes with the transmission of nerve signals between the brain, spinal cord and the rest of the body. Disrupted nerve signals cause the symptoms of MS, which vary from one person to another and over time for any given individual, depending on where and when the damage occurs.

The diagnosis of MS requires evidence of at least two areas of damage in the CNS, which have occurred at different times.”

National Multiple Sclerosis Society