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Myasthenia Gravis

The Neuromuscular Division specializes in the diagnosis and treatment of disorders of the nerves and muscles.


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.


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
si2141 97870 1 thymus gland
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Risk Factors

MG is most common in:


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


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:


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:


Medicine can help to calm the immune system. Options include:


This procedure takes the abnormal antibodies out of the blood. It may need to be repeated in cycles.


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


There are no current guidelines to prevent MG.


  • 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.