Myasthenia gravis

A rare disorder in which the muscles become weak and tire easily. The muscles of the eyes, face, throat, and limbs are most commonly affected. Myasthenia gravis is an autoimmune disorder. In many cases, abnormalities in the thymus gland are present, and in some cases a thymoma is found. Women are affected more often than men. The disease is extremely variable in its effects. In most cases, it causes drooping eyelids, double vision, a blank facial expression, and a weak, hoarse, nasal voice that is hesitant and becomes slurred during extended conversation. The arm and leg muscles may also be affected. In severe cases, the respiratory muscles may become weakened, causing breathing difficulty. Diagnosis of the condition is often made by injecting the drug edrophonium into a vein. This temporarily restores power to the weak muscles. Blood tests and EMG are also sometimes used. CT scanning or MRI may also be performed to look for a thymoma. Treatment with drugs that facilitate transmission of nerve impulses often restores the patient’s condition to near normal. In some cases, the condition often improves, and is sometimes cured by thymectomy (removal of the thymus gland). Regular exchanges of the patient’s plasma for fresh plasma may be carried out in severe cases. Corticosteroid drugs may be given. In a minority of patients, paralysis of the throat and respiratory muscles may lead to death.