Ask an Expert: Response time from plasma exchange

Myasthenia Gravis

Response time from plasma exchange
02/17/2010

Question:

Hello,
My father has been hospitalized for 3 weeks, initially for trouble breathing. After extensive testing, which showed nothing, he has undergone 2 sets of 5 plasma exchanges, and is on prednisone for the treatment of myasthenia gravis. He does not seem to be responding at all to this, and I was wondering what the typical response time is (granted, I know that this is different based on the individual).
Thanks for any information that you can provide.

Answer:

Pheresis is a great rescue treatment in acute myasthenic crisis. Pheresis is the removal of some circulating blood component, like the circulating substance directly responsible for the disease process (acetylcholine receptor antibodies). I usually conduct pheresis treatments every other day for a total of 5 treatments in a series. The usual time I tell people is one to three weeks into starting the pheresis, we should see a response. Usually I see the major signs between treatments three and five, although I have had treatment success as early as after treatment one. In patients with severe myasthenia it can take longer to respond to pheresis, especially when there has been longer pre-pheresis disease. This may be related to more damage to the neuromuscular junction and delay in its repair, despite the antibodies being removed. Changes happen at the neuromuscular junction when it has had an immune system attack for a prolonged period. To use another medical comparison, we took away the knife that was doing the cutting, but the wound still needs to heal. He could also just be in a very active period of his myasthenia.

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Response by:

Robert W Neel, IV, MD
Assistant Professor of Neurology
College of Medicine
University of Cincinnati