Myasthenia Gravis
Next Steps
The Neuromuscular Division specializes in the diagnosis and treatment of disorders of the nerves and muscles.
Definition
Myasthenia gravis (MG) is a disease that damages the communication between nerves and muscles. This can lead to muscle weakness that gets worse over time.
Causes
MG happens when there is a problem with the immune system that causes it to attack a receptor that is needed for nerves to communicate with muscles. The reason why this happens is not known.
In some people, the thymus gland behind the breastbone may play a role. It makes antibodies that tell the body what to attack. The reason why this happens is not known.
The Thymus Gland |
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Risk Factors
MG is most common in:
- Women who are less than 40 years of age
- Men over 60 years of age
- People with a family history of systemic lupus erythematosus
Symptoms
Symptoms may grow worse over time. MG may cause:
- Muscle weakness that increases with activity, and improves with rest
- Drooping eyelids
- Double and blurred vision
- Problems swallowing or speaking
- Trouble walking
- Hand weakness
- Trouble breathing
Diagnosis
The doctor will ask about symptoms and past health. A physical exam will be done. A doctor may be needed who specializes in the nervous system. Tests may include:
- Blood tests—to look for antibodies
- Electromyography —to check the electrical activity of muscles
- Tensilon test—a medicine which will improve muscle strength in people with MG for a short time
Pictures of the thymus may be taken. This can be done with:
Treatment
There is no cure. The goal of treatment is to decrease muscle weakness. It is mainly done by slowing the immune system. A second goal is to avoid a myasthenic crisis. This is when muscles become too weak to let you breathe properly. This is a medical emergency that will need breathing support.
Some people may have a period of time where muscle weakness improves enough to stop treatment. It may be short term or long lasting. Treatment options are:
Medications
Medicine can help to calm the immune system. Options include:
- Acetylcholinesterase inhibitors
- Corticosteroids
- Immunosuppressive drugs
- IV immunoglobulin therapy
Plasmapheresis
This procedure takes the abnormal antibodies out of the blood. It may need to be repeated in cycles.
Surgery
The thymus may be removed. It may improve symptoms. In some people, this may be long lasting.
Supportive Care
Some people may need:
- Mechanical ventilation—if breathing has become difficult
- Physical and occupational Therapy—to improve some muscle weakness and to learn new ways to do daily tasks
Avoiding Medicine That May Worsen Symptoms
Some medicine can worsen MG such as:
- Beta blockers
- Certain antibiotics
- Certain medicine used to treat mental health problems
Prevention
There are no current guidelines to prevent MG.
References
- Juel VC, Massey JM. Myasthenia gravis. Orphanet J Rare Dis. 2007 Nov 6;2:44.
- Myasthenia gravis. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T113873/Myasthenia-gravis .
- Myasthenia gravis fact sheet. National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/disorders/myasthenia%5Fgravis/detail%5Fmyasthenia%5Fgravis.htm.
- What is myasthenia gravis (MG)? Myasthenia Gravis Foundation of America website. Available at: http://www.myasthenia.org/WhatisMG.aspx.
- 11/9/2015 DynaMed Plus Systematic Literature Surveillance http://www.dynamed.com/topics/dmp~AN~T113873/Myasthenia-gravis : Kuo CF, Grainge MJ, Valdes AM, et al. Familial aggregation of systemic lupus erythematosus and coaggregation of autoimmune diseases in affected families. JAMA Intern Med. 2015;175(9):1518-1526.