Myasthenia gravis is a disease that affects the communication between nerves and muscles. The hallmark of this condition is muscle weakness that increases during activity and improves after rest. This disease occurs in men and women of all ethnic groups. Although it most commonly affects women under 40 and men over 60, it can occur at any age.
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." However, most cases of this condition are not as "grave" as the name implies, and most people who have it can expect to live normal or nearly normal lives. The hallmark of myasthenia gravis is muscle weakness that increases during activity and improves after rest. In most cases, the condition affects the muscles that control eye and eyelid movement. This is called ocular myasthenia gravis.
(Click Ocular Myasthenia Gravis for more information.)
Myasthenia gravis may also affect the muscles that control:
- Facial expressions
- Neck and limb movements.
When it affects more than just the eye muscles, it is called generalized myasthenia gravis.
Normally when impulses travel down the nerves, the nerve endings release a neurotransmitter substance called acetylcholine. Acetylcholine travels through the neuromuscular junction and binds to acetylcholine receptors, which are activated and generate a muscle contraction.