Relief from episodic weakness with pyridostigmine in paramyotonia congenita: a family study.
Pyridostigmine relieved episodic weakness in a family with paramyotonia congenita resulting from the R1448C mutation in the sodium channel gene. The transmission was autosomal dominant and the patients had paradoxical myotonia and exercise-induced weakness. On electrophysiological studies there were myotonic potentials, and there was progressive reduction of compound muscle action potential (CMAP) amplitudes after short exercise associated with clinical weakness. Pyridostigmine in doses of 60 mg three times daily abolished the drop in the postexercise CMAP amplitude and reduced the amplitude decrement to slow rate repetitive stimulation, but there continued to be a drop in amplitude on exposure to cold. The decline of the CMAP amplitude on exposure to cold was controlled by treatment with phenytoin. The clinical and electrophysiological features are discussed in relation to therapy with pyridostigmine and phenytoin.
Khadilkar
Satish V
SV
Department of Neurology, Grant Medical College and Sir JJ Group of Hospitals, Mumbai, and Honorary Neurologist, 110, New Wing, First Floor, Bombay Hospital, 12, New Marine Lines, Mumbai, India. khadilkar@vsnl.com
Singh
R K
RK
Mansukhani
K A
KA
Urtizberea
J A
JA
Sternberg
D
D
D000328:Adult; D002800:Cholinesterase Inhibitors / Q000627:therapeutic use; D004576:Electromyography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D018908:Muscle Weakness / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D020967:Myotonic Disorders / Q000150:complications* / Q000188:drug therapy / Q000503:physiopathology; D010375:Pedigree; D011729:Pyridostigmine Bromide / Q000627:therapeutic use*
D002800:Cholinesterase Inhibitors; D011729:Pyridostigmine Bromide