Articles from prior issues of The Advocate

May/June, 1996

Multiple Sclerosis
from MAYO CLINIC HEALTH LETTER, November 1995

NEW LEADS INTO ITS CAUSE AND TREATMENT IMAGINE A LINE OF TRAFFIC MOVING along the freeway that suddenly encounters a large gap in the pavement. Some cars continue in another lane. Others are stopped in their paths. Similarly, in multiple sclerosis (MS), nerve impulses traveling through your central nervous system suddenly meet a disruption in their pathway. Some impulses make it to their destinations; others don’t. About 300,000 Americans have MS, a progressive disease of the central nervous system. Nearly 200 cases of MS are diagnosed each week. Although its cause is unknown, scientists now suspect genetic factors may be at the root of MS. Researchers are also making progress in developing new treatments that not only relieve symptoms but may change the course of the disease.

SIGNALS ARE SHORT-CIRCUITED

Your central nervous system, made up of your brain and spinal cord, contains millions of nerve cells joined by nerve fibers. Electrical impulses originate in nerve cells and travel along the nerve fibers to and from your brain. A fatty substance (myelin) coats and protects the fibers, similar to the way insulation shields electrical wires. In MS, myelin becomes inflamed, swollen and detached from the fibers. Eventually, the detached myelin is destroyed (see illustration). Sclerosed, meaning hardened, patches of scar tissue (lesions) form over the fibers. When nerve impulses reach the damaged area,some impulses are blocked or delayed from reaching your brain. Symptoms vary depending on the location of the lesions in your central nervous system. Blurred or double vision is often the first symptom. Other early symptoms include localized tingling or numbness, hand or leg weakness, fatigue, dizziness and loss of coordination and balance. As the disease gradually worsens, muscle spasms, slurred speech, vision

loss, problems with bladder, bowel or sexual function and paralysis may develop. Occasionally, mental changes such as forgetfulness or confusion occur. A diagnosis of MS is generally based on a complete medical history and neurological examination. The disease may follow three courses:

*Relapsing-remitting - More than half of people with MS have one or two flare-ups every one to three years, followed by periods of remission and recovery. Flare-ups include any of the symptoms of MS alone or in combination.

*Relapsing progressive - Slow deterioration occurs between flare-ups, eventually resulting in some degree of permanent disability.

*Chronic progressive - Neurological function steadily deteriorates without periods of remission. In rare cases, rapid debilitation ends in early death.

GAINING INSIGHT INTO ITS CAUSE

MS is twice as common in women and generally strikes people in their 20s or 30s. Because it most often affects people in northern Europe and the northern half of the United States, scientists suspected environment was a factor. But strong evidence now suggests it results from an autoimmune process in which immune cells attack myelin. People of northern European descent, especially those of Scandinavian heritage, may be genetically predisposed to MS. Many of them settled in the northern United States. Exposure to common viruses or bacteria may trigger the disease in people with a genetic tendency. This may explain why in 70 percent of identical twins in which one twin develops MS, the other doesn’t.

WORKING TO STOP PROGRESSION

MS doesn’t always result in severe disability. Many people actually have little neurological disability and live a normal life span. Early in the course of MS, flare-ups are often self-limited and the main treatment is counseling. As MS progresses, treatment is aimed at relieving symptoms. Corticosteriods are most often prescribed to reduce inflammation and help shorten the duration of flare-ups. In 1993, the Food and Drug Administration (FDA) approved interferon beta-1b (Betaseron), a drug which may reduce MS attacks by up to 30 percent. Yet, Betaseron is approved only for people with relapsing-remitting MS who can still walk. It doesn’t reverse neurologic disability and hasn’t been proven to prevent permanent disability. Plus, injections cost about $10,000 a year. Mayo neurologists generally recommend Betaseron for people who have more than one severe attack a year and those not recovering well from flare-ups. However, researchers are testing whether Betaseron can also help people with moderate to severe disability and progressive disease. Two other drugs with similar benefits are awaiting FDA hearings. Researchers are also evaluating these experimental approaches: *Intravenous immunoglobulin (IVIg) - Antibodies taken from healthy human donors are injected into people with MS to try to stimulate growth of myelin-producing cells. One Mayo study is testing IVIg for rebuilding strength in people with severe muscle weakness. Another focuses on restoring vision in people with optic neuritis caused by destruction of myelin surrounding nerve fibers in your eyes. *Plasma exchange - Factors believed to be involved in immune attacks are removed from blood and exchanged for new plasma. This method may enhance recovery in the small number of people with life-threatening MS who don’t respond to corticosteroids.

SEARCH CONTINUES

Even though scores of treatments have appeared promising over the years, most results have been disappointing. Yet, doctors remain optimistic new therapies will prove to change the course of MS.