Myasthenia gravis

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Symptoms

By Mayo Clinic staff

Muscle weakness caused by myasthenia gravis worsens as the affected muscle is used repeatedly. Since symptoms typically improve with rest, your muscle weakness may come and go. However, the symptoms of myasthenia gravis tend to progress over time, usually reaching their worst within a few years after the onset of the disease.

Although myasthenia gravis can affect any of the muscles that you control voluntarily, certain muscle groups are more commonly affected than others.

Eye muscles
In more than half the people who develop myasthenia gravis, their first signs and symptoms involve eye problems, such as:

  • Drooping of one or both eyelids (ptosis)
  • Double vision (diplopia), which may be horizontal or vertical

Face and throat muscles
In about 15 percent of people with myasthenia gravis, the first symptoms involve face and throat muscles, which can cause difficulties with:

  • Altered speaking. Your speech may be very soft or may sound nasal, depending upon which muscles have been affected.
  • Difficulty swallowing. You may choke very easily, which makes it difficult to eat, drink or take pills. In some cases, liquids you're trying to swallow may come out your nose.
  • Problems chewing. The muscles used for chewing may wear out halfway through a meal, particularly if you've been eating something hard to chew, such as steak.
  • Limited facial expressions. Family members may note that you've "lost your smile" if the muscles that control your facial expressions are affected.

Neck and limb muscles
Myasthenia gravis can cause weakness in your neck, arms and legs, but this usually happens in conjunction with muscle weakness in other parts of your body — such as your eyes, face or throat. The disorder usually affects arms more often than legs. However, if it affects your legs, you may waddle when you walk. If your neck is weak, it may be hard to hold your head erect.

When to see a doctor
Talk to your doctor if you have trouble:

  • Breathing
  • Seeing
  • Swallowing
  • Chewing
  • Walking
  • Using your arms or hands
  • Holding up your head
References
  1. Myasthenia gravis fact sheet. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/myasthenia_gravis/detail_myasthenia_gravis.htm. Accessed July 6, 2010.
  2. Howard J.F. Myasthenia gravis — A summary. Myasthenia Gravis Foundation. http://www.myasthenia.org/hp_clinicaloverview.cfm. Accessed July 9, 2010.
  3. Bird SJ. Clinical manifestations of myasthenia gravis. http://www.uptodate.com/home/index.html. Accessed July 7, 2010.
  4. Bird SJ. Diagnosis of myasthenia gravis. http://www.uptodate.com/home/index.html. Accessed July 7, 2010.
  5. Bird SJ. Treatment of myasthenia gravis. http://www.uptodate.com/home/index.html. Accessed July 7, 2010.
  6. Facts about plasmapheresis. Muscular Dystrophy Association. http://www.mdausa.org/publications/fa-plasmaph.html. Accessed July 9, 2010.
DS00375 Sept. 21, 2010

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