Muscle Diseases - Multiple sclerosis
Multiple sclerosis is a disease in which the myelin sheath that insulates nerves is progressively destroyed through attacks by white blood cells of the immune system. The disease affects mainly the brain and spinal cord. It is termed multiple because there are distinct and separate areas of the nervous system involved, seemingly distributed in a random pattern.
Multiple sclerosis rarely appears before the age of 15 or after 55. A person aged 30 years is statistically at peak risk of developing the disease. The typical patient, statistically speaking, is a woman of 45 who was born and raised in a temperate climate. Women are more susceptible to the disease than men by a ratio of 1.7 to 1, and women are more likely than men to experience the onset of symptoms before the age of 30.
Symptoms and Diagnosis
There are no laboratory tests that are specific for multiple sclerosis, although there are certain tests that may suggest the presence of the disease. Diagnosing the disorder depends to a large extent upon tests that rule out other diseases with similar signs and symptoms. The first symptom may be a transitory blurring of vision or a disturbance in one or more of the limbs, such as numbness, a tingling sensation, clumsiness, or weakness. There may be a partial or total loss of vision in one eye for a period of several days, or the patient may experience double vision, dizziness or pain when moving the eye. In some cases, the patient may develop either a lack of sensation over an area of the face or, paradoxically, a severe twitching pain of the face muscles. In more advanced cases, because of involvement of the spinal cord, the patient may have symptoms of bladder or bowel dysfunction and male patients may experience impotence.
When brain tissues become invaded by multiple sclerosis, the patient may suffer loss of memory and show signs of personality changes, displaying euphoria, cheerfulness, irritability, or depression for no apparent reason.
Multiple sclerosis is marked by periods of remission and recurrence of symptoms. Complete recovery can occur. About 20 percent of the patients may have to spend time confined to bed or wheelchair. In severe cases, there can be complications such as infections of the urinary tract and respiratory system.
There is no known cure for multiple sclerosis and, until recently, treatment techniques generally were aimed at relieving symptoms, shortening the periods of exacerbation, and preventing complications that could be crippling or life-threatening. Most patients experience recurrences of symptoms that last for limited periods of days or weeks, followed in cycles by periods of remission that may last for months or years, making it difficult to determine whether the therapy applied is actually effective or if the disease is merely following its natural fluctuating course.
Among the medications now used are anti-inflammatory drugs such as adrenocorticotrophin (ACTH), a hormone that seems to reduce the severity and duration of recurrences. Cortisone and prednisone, two steroid hormones, also can be used and have an advantage over ACTH in that they can be taken by mouth rather than by intramuscular injection. Not all patients react favorably to steroid drugs and serious side effects may be experienced.
Beta interferon, the first drug to be approved by the FDA for any form of multiple sclerosis, significantly reduces the number of acute episodes of the disease and lessens the severity of the episodes that occur. Recent studies show that it can also significantly delay progression of the disease and reduce the frequency of attacks in people with secondary progressive MS. Brain scans reveal that nerve damage is reduced in patients taking beta interferon.
Physical therapy and antispasmodic medications may be employed for patients suffering weakness or paralysis of the limbs. Bed rest during periods of exacerbation is important; continued activity seems to worsen the severity and duration of symptoms during those periods. Muscle relaxants and tranquilizers may be prescribed in some serious cases and braces could be required for patients who lose some limb functions.
The cause of multiple sclerosis has not been established.
A theory that researchers consider promising suggests that a virus similar but not identical to HTLV-I (human T-cell leukemia virus-I) may cause multiple sclerosis. HTLV-I causes an unusual form of leukemia. Some T-cells, a type of white blood cell, have been found to contain genetic material from this virus. These T-cells were taken from the cerebrospinal fluid of MS victims, establishing a possible link between the cells and the virus.