Myasthenia gravis is an autoimmune disorder that causes a breakdown in the normal communication between nerves and muscles. When an individual is afflicted with myasthenia gravis, abnormalities of the thymus gland cause the immune system to attack against healthy neurotransmitter substances and prevent them from helping muscles contract. This disorder leads to muscle weakness, difficulty swallowing, impaired speech and visual difficulties. It is more common in women under the age of 40 and men over the age of 60. Myasthenia gravis is a degenerative disorder and as it progresses the symptoms get worse.
Causes of Myasthenia Gravis
While the exact cause of myasthenia gravis is unknown, it is considered an immune disorder. In patients with myasthenia gravis, the immune system is not working effectively, causing antibodies to destroy the acetylcholine receptors needed for muscle contraction. Research has indicated that a dysfunction in the thymus gland, which is a part of the immune system, may be the cause of the autoimmune response. In some cases, a tumor may cause the thymus gland to malfunction. Genetics may also be a factor in the development of myasthenia gravis.
Symptoms of Myasthenia Gravis
Myasthenia gravis may lead to debilitating muscle weakness, fatigue, blurred or double vision and impaired speech. As the muscles that control these actions continually weaken, symptoms worsen. It affects the voluntary muscles of the body, particularly in the throat, mouth, eyes and limbs. Additional symptoms may include:
- Drooping of the eyelids
- Difficulty swallowing
- Problems chewing
- Weakness in the neck, arms or legs
The muscle weakness caused by myasthenia gravis is typically more pronounced during periods of activity and less evident during periods of rest.
Diagnosis of Myasthenia Gravis
To diagnose myasthenia gravis, the patient's symptoms and medical history are reviewed. A thorough physical examination is also performed. Blood tests are commonly performed in conjunction with some of the following tests to confirm the diagnosis of myasthenia gravis:
- Edrophonium test
- CT scan
- MRI scan
- Pulmonary function tests
- Nerve stimulation test
A neurological examination to test reflexes, muscle strength, muscle tone, coordination and balance may also be performed to confirm a diagnosis.
Treatment of Myasthenia Gravis
Medication is usually effective in treating the symptoms of this condition and increasing muscle strength, and is often the preferred treatment. Medication to treat myasthenia gravis may include:
- Cholinesterase inhibitors
A blood filtering procedure known as plasmapheresis, may also be helpful to remove the antibodies from the blood, however the benefits of this process are often temporary. In some cases, especially if there is a tumor within the thymus gland, surgery may be necessary. A surgical procedure called a thymectomy, involves removing the entire thymus gland. If the thymus gland is removed, symptoms of myasthenia gravis may be eliminated and medication for the condition can often then be stopped. In some patients, however, the benefits of a thymectomy may not be completely noticeable for several years.