Myasthenia gravis (mi-uhs-THEE-ne-uh GRA-vis) is characterized by weakness and rapid fatigue of any of the muscles under your voluntary control. The cause of myasthenia gravis is a breakdown in the normal communication between nerves and muscles.
There is no cure for myasthenia gravis, but treatment can help relieve signs and symptoms — such as weakness of arm or leg muscles, double vision, drooping eyelids, and difficulties with speech, chewing, swallowing and breathing.
While myasthenia gravis can affect people of any age, it's more common in women younger than 40 and in men older than 60.
Muscle weakness caused by myasthenia gravis worsens as the affected muscle is used repeatedly. Since symptoms typically improve with rest, your muscle weakness may come and go. However, the symptoms of myasthenia gravis tend to progress over time, usually reaching their worst within a few years after the onset of the disease.
Although myasthenia gravis can affect any of the muscles that you control voluntarily, certain muscle groups are more commonly affected than others.
Face and throat muscles
Neck and limb muscles
When to see a doctor
Your nerves communicate with your muscles by releasing chemicals, called neurotransmitters, which fit precisely into receptor sites on the muscle cells. In myasthenia gravis, your immune system produces antibodies that block or destroy many of your muscles' receptor sites for a neurotransmitter called acetylcholine. With fewer receptor sites available, your muscles receive fewer nerve signals, resulting in weakness.
It's believed that the thymus gland — a part of your immune system situated in the upper chest beneath the breastbone — may trigger or maintain the production of these antibodies. Large in infancy, the thymus is small in healthy adults. But, in some adults with myasthenia gravis, the thymus is abnormally large. Some people also have tumors of the thymus. Usually, thymus gland tumors are noncancerous.
Factors that can worsen myasthenia gravis
Chemicals messengers, called neurotransmitters, fit precisely into receptor sites on your muscle cells. In myasthenia gravis, certain receptor sites are blocked or destroyed, causing muscle ...
The thymus gland, a part of your immune system situated in the upper chest beneath the breastbone, may trigger or maintain the production of antibodies that result in the muscle weakness. ...
Complications of myasthenia gravis are treatable, but some can be life-threatening.
Preparing for your appointment
After you discuss your symptoms with your family doctor, he or she will probably refer you to a neurologist for further evaluation.
What you can do
What to expect from your doctor
Tests and diagnosis
The key sign that points to the possibility of myasthenia gravis is muscle weakness that improves with rest. Tests to help confirm the diagnosis may include:
Repetitive nerve stimulation
Single-fiber electromyography (EMG)
Treatments and drugs
Doctors use a variety of treatments, alone or in combination, to relieve symptoms of myasthenia gravis.
For people with myasthenia gravis who don't have a tumor in the thymus, it's unclear whether the potential benefit of removing the thymus outweighs the risks of surgery.
Surgery is not recommended by most doctors if:
Lifestyle and home remedies
Supplementing your medical care with these approaches may help you make the most of your energy and cope with the symptoms of myasthenia gravis:
Last Updated: 2010-09-21
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