got myasthenia gravis?

Myasthenia gravis is an autoimmune disease that is characterized by weakness of the skeletal muscles.

Symptoms

The symptoms include muscle weakness that increases during activity and decreases after resting. It also tends to vary in type and severity among affected individuals.

The symptoms of myasthenia gravis depend on the muscle involved. Since it can affect any skeletal muscle in the body its symptoms include drooping eyelids, difficulty swallowing, slurred speech, shortness of breath, a waddling gait and weakness in the neck, arms and legs.

Cause

Myasthenia gravis is caused by a breakdown in the normal transmission of nerve impulses to muscles at the neuromuscular junction. Normally impulses travel down a nerve to the nerve endings where a neurotransmitter or signaling chemical like acetylcholine is released. This neurotransmitter then binds to its receptors on the muscle and causes it to contract.

In myasthenia gravis, the body’s immune system produces antibodies that jam the acetylcholine receptors on the muscle and this prevents the muscle from contracting.

Evaluation

Diagnostic tests for myasthenia gravis include a blood test which detects the presence of acetylcholine receptor antibodies. However, this antibody is not present in all patients with myasthenia gravis.

Repetitive nerve stimulation is another test which can be done for patients suspected to have myasthenia gravis. In this procedure the doctor attaches electrodes to the skin over the muscles. Tiny currents of electricity are then sent through the electrodes to measure the nerve’s ability to send signals to the muscle. In myasthenia gravis this ability usually worsens as the muscle becomes fatigued.

Single fiber electromyography is another diagnostic investigation in which a fine wire is inserted into the muscle to measure the electrical activity between a single muscle fiber and the brain.

The edrophonium test is sometimes completed assist in confirmation of the diagnosis of myasthenia gravis. In this test, edrophonium chloride (Tensilon) is given in the vein to temporarily relieve muscle weakness since it prevents the breakdown of acetylcholine.