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Isaacs Syndrome

(Isaacs' Syndrome; Neuromyotonia)

By Michael Rubin, MDCM, Professor of Clinical Neurology;Director, Neuromuscular Service and EMG Laboratory, Weill Cornell Medical College;New York Presbyterian Hospital-Cornell Medical Center

Isaacs syndrome involves overstimulation of the nerves that stimulate muscle fibers. It causes progressive muscle stiffness, continuous muscle quivering and twitching and cramping.

This syndrome is rare and appears to be caused by an antibody that attacks a specific part of the cell membrane. Isaacs syndrome often occurs in people with other disorders, such as cancer, including some thymomas, small cell lung cancer, and Hodgkin lymphoma. It can also be inherited.

Muscles, particularly those in the arms and legs, continually quiver and twitch, moving like a bag of worms. This symptom is called myokymia. Spasms and cramps may intermittently occur in the hands and feet. Muscles often become progressively stiffer and take a long time to relax after they have been contracted. Sweating may be increased.


  • Carbamazepine or phenytoin (anticonvulsants)

  • Immune globulin and plasma exchange

Symptoms can be relieved by the anticonvulsants carbamazepine or phenytoin.

People may also benefit from immune globulin (a solution containing many different antibodies collected from a group of donors), given intravenously, and plasma exchange (filtering of toxic substances, including abnormal antibodies, from the blood).

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* This is the Consumer Version. *