What is myasthenia gravis?
Myasthenia gravis is a neuromuscular, autoimmune disorder. It is characterized by a fluctuating weakness in a person's muscles, and fatiguability (lack of energy). This weakness is caused by antibodies that block post-synaptic acetylcholine receptors in the neuromuscular junction. Acetylcholine is a neurotransmitter, which as one of its many functions, is responsible for movement. When these receptors are blocked in the brain stimulation of a person's muscles are blocked. It is a rare disorder to have.
To treat it a person takes medication usually either cholinesterase inhibitors or immunosuppresants. Cholinesterase inhibitors inhibit the breakdown of acetylcholine in the brain, which means there is more available. Immunosuppresants suppress the immune system decreasing the chance that a person's antibodies will block the acetylcholine receptors.
Myasthenia means muscle weakness, myasthenic gravis is an autoimmune motor disorder caused by a decreased number of receptor sites for the skeletal muscle neurotransmitter acetylcholine. The body produces antibodies to acetylcholine at the neuromuscular junction (nm) . The exact reason this occurs is unknown. The disease produces symptoms of muscle fatigue that are disproportionate to normal every day activity. It is a fairly rare disorder.
Any skeletal muscle can be affected but commonly the muscles of the eyes, pharynx, and mastication become easily fatigued. This affects normal functioning of these muscle groups and can lead to disability. Sometimes people suffer from double vision (diplopia) and drooping of the upper eyelids (ptosis). The act of chewing and swallowing food may become progressively more difficult.
People with myasthenia gravis often experience very rapid muscle fatigue and weakness, and this is related only to muscles that are voluntary. When this occurs, there is something going on with the communication between the nerves and the muscles.
There is no cure for myasthenia gravis but there are treatments available, such as certain medications, therapy, or surgery. Some of the common muscles that are affected by myasthenia gravis are the eye muscles, face and throat muscles, and arm and leg muscles. Symptoms include drooping eyelids, blurred vision, difficulty speaking or swallowing, and weak arms or legs.
Tests used to confirm myasthenia gravis are edrophonium tests, blood tests, repetitive nerve stimulation, EMG, and imaging scans.