Myasthenia Gravis

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*Myasthenia gravis facts medical author: Charles Patrick Davis, MD, PhD

• Myasthenia gravis is a chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal (voluntary) muscles of the body.
• Myasthenia gravis is caused by a defect in the transmission of nerve impulses to muscles.
• The thymus may give incorrect instructions to developing immune cells, ultimately resulting in autoimmunity and the production of the acetylcholine receptor antibodies.
• The symptoms of myasthenia gravis may include eye muscle weakness, eyelid drooping (ptosis), blurry or double vision (diplopia),unstable gait, a change in facial expression, difficulty in swallowing, shortness of breath, impaired speech, and weakness in the arms, hands, fingers, legs, and neck.
• The disease is not directly inherited nor is it contagious; it commonly affects adult women (under 40) and older men (over 60), but it can occur at any age.
• Diagnosis is often delayed because muscle weakness is a common symptom in other diseases and may slowly develop; diagnostic tests that help confirm the diagnosis include detecting the presence of immune molecules or acetylcholine receptor antibodies, edrophonium test, and electromyography.
• Medical treatment includes anticholinesterase agents, plasmapheresis, and various immunosuppressive drugs; surgical treatment may include removal of the thymus.
• A myasthenic crisis occurs when the muscles that control breathing weaken so much that the patient requires emergency ventilation assistance.
• The disease prognosis is highly variable; some patients have complete remission (about 50% with thymus surgery), others have relatively normal lives with continued treatment, and others have a poor prognosis as the disease advances.
• Research is ongoing; new treatment protocols and immunosuppressive drugs are being investigated and therapeutic methods are likely to improve in the future.