Myasthenia Gravis

Myasthenia gravis is a relatively rare neuromuscular disease characterized by increasing weakness of voluntary muscles, especially those controlling the eyelids and the parts of the mouth and throat used in speaking and swallowing. Typically, the first symptoms are droopy eyelids and double vision. As the disease progresses, facial expressions become difficult to control; for example, a person trying to smile may appear to be snarling. Chewing, swallowing, and speaking are also impaired.

Problems eventually develop in the arms and legs, which can lead to difficulty in walking and lilting objects. In about 10 percent of sufferers, breathing muscles are affected, in which case an artificial respirator may be needed. The rate of progression varies greatly, about 25 percent of patients go into spontaneous, often permanent remission, while others decline rapidly and experience widespread muscle weakness.

Women are stricken more often and at a younger age than men. Babies born to women with the disease frequently develop symptoms at an early age. What triggers myasthenia gravis is unknown, but it is classified as an autoimmune disease, in which the immune system destroys cells located at the junction of muscles and nerves. People with other autoimmune diseases appear more susceptible to myasthenia gravis, as are those with a history of a thymus tumor or lung cancer.

Diagnostic Studies and Procedures

If symptoms raise a suspicion of the disease, blood tests may be done to look for antibodies to acetylcholine, a body chemical that transmits nerve messages. Diagnosis can be confirmed by the persons response to an intravenous anticholinesterase drug, such as edrophonium, which produces an immediate, albeit temporary, improvement in muscle strength in people with myasthenia gravis. Additional tests may include electromyography to measure electrical activity in muscle cells, and a CT scan to look for a thymus tumor.

Medical Treatments

Anticholinesterase medications such as pyridostigmine (Mestinon) or neostigmine (Prostigmin) are the first line of treatment. Dosages and timing vary according to needs. For example, a person with swallowing problems may benefit by taking the medication before a meal. Most patients improve with these drugs, but few recover completely.

A blood cleansing technique called plasmapheresis is often used during a crisis or to strengthen a patient for surgery. The person is hooked up to a machine that separates plasma from other blood components. Once separated, the cleansed plasma is returned to the patient's bloodstream. Plasmapheresis usually produces marked short-term improvement.

In some cases, the thymus is taken out, even if the gland is free of a tumor, because the operation prompts a remission in some patients. Those who benefit most are under age of 50 and have only recently developed symptoms.

Steroids and other drugs that suppress the immune system can slow progression of the disease, but their many side effects -- lowered immunity, easy bleeding, mood swings, weight gain, and thinning of bones, skin, and other tissues -- preclude their long-term use. A myasthenic crisis, during which difficulty in breathing or swallowing becomes life threatening, requires hospitalization for artificial respiration and intravenous feeding, if necessary.

Alternative Therapies

Alternative therapies should be adjuncts to conventional treatments and used only with the approval of a specialist in neuromuscular disorders. Therapies most likely to help are those that reduce stress and strengthen the immune system, such as meditation and visualization. The gentle exercises of yoga and t'ai chi are particularly suitable, because they build strength and endurance without undue exertion.

Self-Treatment

Adequate rest is essential, as weakness is less pronounced after resting or sleeping. Set aside several rest periods each day, but strive for balance; too much rest accelerates muscle weakness. Because a myasthenic crisis can come on suddenly, you should carry an anticholinesterase drug with you at all times Also, wear a medical bracelet to alert emergency personnel to your condition.

Other Causes of Muscle Weakness

Symptoms suggesting myasthenia gravis may be caused by drugs such as penicillamine and some types of antibiotics. Thyroid disease should also be ruled out.