What is Myasthenia Gravis?

Myasthenia gravis is a relatively rare, chronic autoimmune neuromuscular disease that results in progressive skeletal (voluntary) muscle weakness. MG causes rapid fatigue that increases during periods of activity and improves after periods of rest. The name comes from Greek and Latin words meaning “grave muscle weakness”.

How does MG Work?

MG impacts muscles controlled by sending signals from the brain to contract. These are muscles that are used to open or close your eyelids, smile, chew, swallow, hold your head erect, breathe, and move your arms and legs.

Normally, a nerve impulse goes from the brain to the muscle. The nerve releases a chemical messenger called Acetycholine that swims over the small gap between the nerve and muscles that is called the neuromuscular junction. It then hooks onto receptors on the other side that causes the muscle to contract. In someone with MG, antibodies hook onto the receptor sites which cause the Aceytycholine to be unable to hook onto the receptor site and cause muscle contraction. Individuals with MG produce these antibodies that destroy receptor sites so fast that the body can’t replace them.