Ask the Experts: Is plasmapheresis an effective treatment for myasthenia gravis?

Neurology Now
October/November 2011
Volume 7(5)
p 66
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MYASTHENIA GRAVIS

QIs plasmapheresis an effective treatment for myasthenia gravis?

DR. JULIE ROWIN RESPONDS:

Figure. No caption available.

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A Several treatment options are available for people with myasthenia gravis (MG). In my experience, plasmapheresis (plasma exchange) has been the most effective in treating the severe symptoms of an MG crisis, such as difficulty breathing or swallowing. But while plasmapheresis reverses severe symptoms of MG in an exacerbation quickly, the effect can be short-lived.

A rare autoimmune disease, MG causes weakness in the voluntary muscles. In people with MG, these muscles rapidly grow weaker with repeated use (and then recover after a period of rest). Myasthenia gravis is caused by an abnormal antibody in the blood that prevents a substance in nerve cells, called acetylcholine, from doing its job. This neurotransmitter communicates with muscles, telling them to contract. The muscles affected by MG often involve those that control eye and eyelid movement, vision, swallowing, chewing, and breathing. With treatment, many people with MG improve significantly.

During plasmapheresis, the fluid part of the blood (plasma) containing the abnormal antibodies is removed and replaced with other fluids before being returned to the patient. Since the effects are often short-term (generally two weeks), a series of treatments over a period of weeks is usually necessary, typically on an outpatient basis. The process can be costly, and potential risks exist, such as a dangerous drop in blood pressure, bleeding as a result of anticoagulants used with the procedure, and possible infection in cases where a peripheral vein (a vein not in the chest or abdomen) cannot be used and a catheter must be inserted into the chest.

Intravenous immunoglobulin (IVIG) is another treatment used to treat serious or worsening cases of MG. Rather than removing abnormal antibodies, IVIG involves the injection of serum containing antibodies in order to affect the immune system's own antibody production. Treatments last three to four weeks and are done by IV through a peripheral vein. For the most part, side effects are mild and may include chills and headache during and after infusion, although some patients may be at risk of serious adverse events such as anaphylactic shock or kidney failure.

Plasmapheresis and IVIG have been shown to be comparable in clinical trials. Whereas plasmapheresis has yet to be compared to placebo in clinical trials, IVIG has been compared to placebo and been shown to be effective in MG, particularly in moderate disease. Most experts believe that plasmapheresis is more potent and reliable in treating patients who are in crisis. When choosing between the two treatments, several factors are considered, including severity of the symptoms and potential side effects for the individual. Whichever treatment you choose, the decision should be made in the context of a long-term strategy to keep the MG under control.

Figure. Ptosis (drooping of the eyelid) is one of the common symptoms of of myasthenia gravis.

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