Neuroscience Network - Myasthenia Gravis (MG)
This autoimmune, neuromuscular disease is characterized by the varying weakness of voluntary muscle groups. Those commonly affected include the eye muscles, facial and throat muscles, shoulder and hip muscles. Muscles that assist breathing also may be involved. The weakness in the muscles caused by Myasthenia Gravis fluctuates significantly; it can be made worse by use of the affected muscles, and improved at least partially by rest.
Symptoms
* drooping eyelids
* double vision
* slurred speech
* nasal quality to voice
* inability to speak
* drooling
* problems chewing and/or swallowing
* trouble sitting up or holding head erect
or walking
* weak cough
* shortness of breath
* easily tired
* fatigue of muscles after repetitive movement
Myasthenia Gravis can generate medical emergencies when respiratory muscles become so weak that respirations are shallow and ineffective, or the airway becomes obstructed due to weakened posterior pharyngeal muscles and accumulated secretions. Failure to treat symptoms promptly can result in severe hypoxia (decrease in oxygen) and respiratory arrest.
Testing
Diagnosing Myasthenia Gravis begins with a complete neurological history and clinical evaluation. Specifically, your physician will be looking for signs of weakness in your voluntary muscles that get worse with activity and improve with rest.
Tensilon is a fast-acting drug that, in the event of Myasthenia Gravis, will make the patient's muscle function improve dramatically for about three to five minutes.
There is also a blood test that checks for elevation of the AchR antibody in the blood. Your doctor may also suggest a repetitive nerve stimulation test, in which electrodes are placed over the muscle to record electrical shocks delivered to the nerve at the rate of three per second.
A single fiber electromyography or EMG is about 99 percent accurate in confirming Myasthenia Gravis. It detects the failure of neuromuscular transmission in pairs of muscle fibers that are supplied by branches of a single nerve fiber.
Chest x-ray, CT scan and MRI may also be administered to detect thymoma (tumor of the thymus gland).
* MRI (Magnetic Resonance Imaging): This procedure uses a tunnel-shaped piece of equipment that contains a magnetic field and radio energy; no x-rays are involved. Magnetic signals are fed into a computer which assembles a picture. Because the MRI ignores bone which can obstruct CT images, this device provides a clearer picture of tumors located near the bone, and can provide a wider variety of image angles. It can detect edema (swelling), but has difficulty distinguishing edema from a tumor. MRI imaging takes longer than a CT scan, and is very noisy. Patients with cardiac monitors, pacemakers or surgical clips cannot take an MRI because of conflict with the magnetic fields.
Treatment
There is no cure for Myasthenia Gravis, though the ability to treat its symptoms continues to improve, and patients are surviving with improved quality of life. Common-sense lifestyle modifications can also be very effective in dealing with Myasthenia Gravis. These include:
* Get plenty of rest, and specifically rest the affected muscles several times a day.
* Pace your activities so as not to become over-fatigued.
* Be as vigilant as you can at avoiding infection and exposure to illnesses.
* Eat a well-balanced diet, with preference given to foods high in potassium, such as oranges, tomatoes, apricots and their juices, bananas, broccoli and white meat. Avoid foods that require excess chewing.
There are also a number of medications that can aid in the short-term to counteract the bothersome symptoms of MG. These include:
Anticholinesterases: There are several different versions and brand-names for this type of drug. They do not offer any kind of a cure for MG, but they may provide temporary relief to help some patients function better. (Please note, however, that some patients may be unresponsive to these drugs, and others may get weaker as a result of using them.) They may also cause side effects, including stomach cramps, and so should be taken with bland food to minimize these problems.
Ephedrine sulphate: This drug, formerly used before anticholinesterases, may be used in addition to the newer drugs to provide extra strength. This drug is most effective for patients who are not bothered by the possible side effects of nervousness, palpitations and insomnia.
Plasmapheresis: A short-term treatment in which several liters of blood are removed from the patient's vein, spun in a centrifuge, and the red blood cells returned intravenously in artificial plasma. It is used every other day for two weeks. Some patients get stronger as a result of the procedure, but the benefit lasts only weeks. It appears to work by "cleaning" the blood of harmful antibodies.
Intravenous human immune globulin: Another short-term treatment, it swamps the body with pooled gamma globulin antibodies from many donors. It is thought to have a nonspecific suppressive effect on the immune system, but if benefits occur, they last only a few weeks. Plenty of fluids should accompany the treatments to minimize the severe headaches which can occur.
Long-term treatments include:
Thoracic surgery: This includes thymectomy, or removal of part or all of the thymus gland. This can be done in response to a tumor of the thymus gland (thymoma), and is often helpful even in the absence of thymoma.
There are several different surgical techniques for performing this, and which patients are best candidates for it must be decided on an individual basis. In some patients this can lessen symptoms or eliminate them altogether.
Immunosuppressive drug therapy: These drug alternatives consist of a group of general suppressants of the body's immune system (steroids) although no one knows exactly how they work in addressing this disorder. Your doctor can give you specific information about these drugs in treating your symptoms.
Research
The most promising new development in Myasthenia Gravis research in the U.S. is to harvest a patient's own mesenchymal stem cells (found in the bone marrow), grow and engineer them to be able to attack and destroy disease-causing cells in the body, then reinfuse them into the patient.
Support Groups/Resources
Many patients and families find great comfort and support in talking with other patients, families and caregivers who have had (or are having) similar experiences. Support group meetings are free of charge, and are facilitated by a trained peer or qualified professional. For more information, or a list of support groups nearest you, call:
The Myasthenia Gravis Foundation:
1-800-541-5454
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