Myasthenia gravis is an autoimmune disease characterized by weakness and rapid fatigue of voluntary muscles. It is caused by a defect in the communication between the nerves and muscles. The body’s own immune system mistakenly creates antibodies that block or alter nerve impulses to muscles.
Myasthenia gravis often affects muscles that control eye and eyelid movement, facial expressions, chewing, talking, and swallowing. However, any muscle that a person voluntarily controls can be affected. Muscle weakness tends to worsen with activity and improve with rest.
Some people with myasthenia gravis may also have a thymoma, a tumor of the thymus gland. Thymomas are usually benign, but can become malignant.
How common is myasthenia gravis?
The prevalence of myasthenia gravis in the United States is estimated at 14 to 20 cases per 100,000 people.
Who gets myasthenia gravis?
Myasthenia gravis can affect anyone, regardless of age, gender, or ethnicity. However, it is more common in women younger than 40 years old and in men older than 60.
How is myasthenia gravis diagnosed?
In addition to reviewing your medical history and conducting a physical examination, your doctor may use several tests to diagnose myasthenia gravis.
The following tests are used to evaluate nerve and muscle function:
- neurological exam
- edrophonium test
- single fiber electromyography (EMG)
- repetitive nerve stimulation
- pulmonary function testing
Blood tests may be able to detect the antibodies that disrupt communications between the nerves and muscles.
Usually, the first symptoms of myasthenia gravis involve eye problems. In some cases, the first symptoms involve face and throat muscles. Muscle weakness can occur in your neck, arms, and legs, but it usually happens along with weakness in other parts of your body, such as your eyes, face, or throat.
Specific symptoms of myasthenia gravis may include:
- drooping of one or both eyelids (ptosis)
- blurred or double vision (diplopia)
- impaired speech (dysarthria)
- difficulty swallowing
- difficulty chewing
- limited facial expressions
- shortness of breath
- unstable or waddling gait
- weakness in arms, hands, fingers, neck, and legs
Contact a medical professional if you are having the symptoms described above or if you are generally worried about your health.
Although there is no known cure for myasthenia gravis, a variety of treatment options can help relieve symptoms:
- Medications – Cholinesterase inhibitors may be used to enhance communication between nerves and muscles, and corticosteroids or immunosuppressants may be used to limit the activity of your immune system.
- Infusion Therapies – Plasmapheresis (plasma exchange) may be used to filter the antibodies out of your blood that are interrupting signals between nerves and muscles. Intravenous immunoglobulin therapy can alter your immune system response by providing your body with normal antibodies.
- Surgery – A thymectomy, or surgical removal of your thymus gland, may be necessary if you have a thymoma. This may be done through open surgery or a minimally invasive procedure. Thymectomy may reduce symptoms of myasthenia gravis even if you do not have a thymoma. Your doctor will help you determine if you are a good candidate for a thymectomy.
- Date of last review: September 23, 2015