An autoimmune disorder that affects the skeletal muscles, myasthenia gravis affects both women and men. While the disorder can occur at any age, it is more common in women who are under age 40 and men who are over age 60.
Juel and Massey noted that under age 40, the ratio of women to men with the disorder is seven to three. After age 50, the ratio of women to men is two to three. Patients with myasthenia gravis experience muscle weakness due to interference with the acetylcholine receptors in the neuromuscular junction. The immune system produces antibodies that either block or damage these receptors, which prevents muscle contraction.
The major symptom of myasthenia gravis is muscle weakness of the voluntary muscles. Patients can have a variety of issues because of the muscle weakness. For example, the muscle weakness may cause problems with chewing and swallowing. MedlinePlus noted that this difficulty can result in drooling, choking and frequent gagging.
Vision trouble can occur with myasthenia gravis, such as double vision and problems keeping a steady gaze. Patients can also have eyelid drooping, which may occur in one or both eyes. More than 50 percent of patients with myasthenia gravis have eye problems as their first symptoms, according to the MayoClinic.com.
Myasthenia gravis can also affect patients’ movements. For example, patients may have trouble climbing stairs or getting up from a chair. Muscle weakness in the arms can cause trouble lifting an object. The MayoClinic.com stated that arms are affected more often than legs.
Muscle weakness in the face can occur, causing facial paralysis. Patients may have a dropping head. If a patient has muscle weakness in the chest wall muscles, the patient can have trouble breathing. Other symptoms of myasthenia gravis include difficulty talking, fatigue, a changing voice or hoarseness.
While myasthenia gravis can affect any of the voluntary muscles, the MayoClinic.com noted that certain muscles are affected more commonly. The symptoms of the disorder become progressively worse, and the muscle weakness becomes worse as the muscle is used more often. Patients may have their muscle weakness come and go with rest.
References
Vern C. Juel and Janice M. Massey. “Myasthenia Gravis.” Orphanet Journal of Rare Diseases. 2007. Web. 17 October 2011
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2211463
National Institute of Neurological Disorders and Stroke. Myasthenia Gravis Fact Sheet. Web. 17 October 2011
http://www.ninds.nih.gov/disorders/myasthenia_gravis/detail_myasthenia_gravis.htm
MedlinePlus Medical Encyclopedia. Myasthenia Gravis. Web. 17 October 2011
http://www.nlm.nih.gov/medlineplus/ency/article/000712.htm
MayoClinic.com. Myasthenia Gravis. Web. 17 October 2011
http://www.mayoclinic.com/health/myasthenia-gravis/DS00375/METHOD=print
Reviewed October 17, 2011
by Michele Blacksberg RN
Edited by Jody Smith