Myasthenia Gravis (MG) is an autoimmune disease affecting the neuromuscular junction and producing weakness of voluntary muscles. It is a chronic disease deriving its name from Latin and Greek words meaning ¨grave muscle weakness¨. The usual cause ia an aquired immunological abnormality but in some cases it results of genetics abnormalities at the neuromuscular junction.
MG is a muscle weakness that increases during periods of activities and improves after periods of rest. Certain muscles suck as those that control eye and eyelid movement, facial expression, chewing , talking, and swallowing are often,but not always, involved in the disorder.
MG is caused by the transmission of nerve impulses to the muscle. It occurs when normal communication between the nerve and muscle is interrupted at the neuromuscular junction (place where never cells connect with the muscle they control).
Normally, when impulses travel down the nerve, the nerve endings release a neurotransmitter substance called acetycholine. Acetycholine travels through the neuromuscular junction and binds to the acetycholine receptors which are activated and generate a muscle contraction.
Mg causes antibodies block, alter, or destory the receptors for acetylcholine at the neuromuscular junction which prevents the muscle contraction from occurring. These antibodies are produced by the body's own immune system.
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