Treatment of paramyotonia congenita with acetazolamide.

Treatment of paramyotonia congenita with acetazolamide has been shown to reduce myotonic symptoms but severe weakness has developed in some patients leading to a recommendation not to use the drug in this disorder. We studied a patient with the characteristic clinical and electrophysiological profile of paramyotonia congenita. Myotonia was effectively treated with a very low dose of acetazolamide and no weakness developed. We conclude that acetazolamide can be a safe and effective medication in paramyotonia congenita.