Myasthenia Gravis

Myasthenia gravis is an autoimmune disease that affects the transmission of signals from nerves to muscles. The name myasthenia gravis comes from Greek and Latin words meaning "grave muscle weakness." Today, however, most cases of MG are not as "grave" as the name implies. In fact, most people with MG can expect to live normal or nearly normal lives.

The hallmark of MG is muscle weakness that increases during activity and improves after rest. MG often involves muscles that control eye and eyelid movement, facial expression, chewing, talking, and swallowing. The muscles that control breathing and neck and limb movements may also be affected.

The thymus gland, part of the immune system, is abnormal in most MG cases. Some people with MG have benign (noncancerous) tumors of the thymus gland called thymomas.

Some drugs can trigger or worsen MG symptoms.