The root cause of MG is unknown. It occurs when the body’s immune system attacks receptors in muscle. Normally, these receptors respond to the chemical acetylcholine (ACh). This chemical allows nerve signals to prompt the muscles to move. When the immune system prevents these receptors from working well, the muscles cannot respond to nerve signals.
The thymus is thought to play a role in some cases of MG. The thymus is an organ behind the breastbone. Immune proteins called antibodies are produced there. It is these antibodies that may target the ACh receptors. It is still not clear why the thymus begins to produce these.
Infants of mothers with MG are more likely to develop a temporary form. It is called neonatal MG. The mother’s abnormal antibodies enter the baby’s bloodstream. When the baby is born, there may be muscle weakness. The abnormal antibodies are often cleared from the baby in about 2 months. This will end the baby’s symptoms.
You will be asked about your symptoms and medical history. A physical exam will be done. You will likely need to see a neurologist. This type of doctor is an expert in diseases of the nervous system. Tests may include:
is a procedure that cleans the blood of the abnormal antibodies. This process may need to be repeated at certain intervals.
is a surgical procedure to remove the thymus gland. Surgery may improve symptoms or bring remission in some people.
This may only be needed if breathing is severely impaired. This can happen during an episode of myasthenic crisis.
Physical and Occupational Therapy
Therapy does not generally alter the course of the disease. It may be needed to help the person cope with changes in muscle strength. It may also help with learning alternative ways to approach daily activities.
Avoiding Medications That May Worsen Symptoms
Avoid medications that may worsen MG. Some examples include:
Certain medications used to treat psychiatric conditions
Gronseth GS, Barohn RJ. Practice parameter: Thymectomy for autoimmune myasthenia gravis (an evidence-based review): Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2000;55(1):7-15.
Myasthenia gravis fact sheet. National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/disorders/myasthenia_gravis/detail_myasthenia_gravis.htm. Accessed October 2, 2017.
What is myasthenia gravis (MG)? Myasthenia Gravis Foundation of America website. Available at: http://www.myasthenia.org/WhatisMG.aspx. Accessed October 2, 2017.
11/9/2015 DynaMed Plus Systematic Literature Surveillancehttp://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.
Last reviewed September 2017 by
EBSCO Medical Review Board Rimas Lukas, MD
Last Updated: 11/9/2015
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