Multiple sclerosis (MS) is a disease in which your immune system attacks the protective sheath (myelin) that covers your nerves. Myelin damage disrupts communication between your brain and the rest of your body. Ultimately, the nerves themselves may deteriorate, a process that’s currently irreversible.
Signs and symptoms vary widely, depending on the amount of damage and which nerves are affected. Some people with severe MS may lose the ability to walk independently or at all, while others experience long periods of remission during which they develop no new symptoms.
There’s no cure for multiple sclerosis. However, treatments can help speed recovery from attacks, modify the course of the disease and manage symptoms.
The cause of multiple sclerosis is unknown. It’s believed to be an autoimmune disease, in which the body’s immune system attacks its own tissues. In MS, this process destroys myelin — the fatty substance that coats and protects nerve fibers in the brain and spinal cord.
Myelin can be compared to the insulation on electrical wires. When myelin is damaged, the messages that travel along that nerve may be slowed or blocked.
It isn’t clear why MS develops in some people and not others. A combination of factors, ranging from genetics to childhood infections, may play a role.
Signs and symptoms of multiple sclerosis vary, depending on the location of affected nerve fibers. MS signs and symptoms may include:
- Numbness or weakness in one or more limbs that typically occurs on one side of your body at a time, or the legs and trunk
- Partial or complete loss of vision, usually in one eye at a time, often with pain during eye movement
- Double vision or blurring of vision
- Tingling or pain in parts of your body
- Electric-shock sensations that occur with certain neck movements, especially bending the neck forward
- Tremor, lack of coordination or unsteady gait
- Slurred speech
- Problems with bowel and bladder function
Most people with MS have a relapsing-remitting course, with new symptoms (relapse) that develop over days or weeks and usually improve partially or completely, followed by a quiet period (remission) that can last months or even years. Small increases in body temperature can temporarily worsen signs and symptoms of MS, but that type of event isn’t a relapse.
About 60 to 70 percent of people with relapsing-remitting MS eventually develop a steady progression of symptoms, with or without periods of remission (secondary-progressive MS). The worsening symptoms usually include problems with gait. The rate of progression varies greatly among people with secondary-progressive MS.
Some people with MS experience a gradual onset and steady progression of signs and symptoms with no relapses (primary-progressive MS).