Neuromyotonia in the spinal form of Charcot-Marie-Tooth disease.

The term neuromyotonia has been applied to spontaneous activity of peripheral motor nerves which gives rise to pseudomyotonia, muscular fasciculations and myokymia. A family is described in which 8 members of 3 generations suffer from the spinal form of Charcto-Marie-Tooth disease (distal type of chronic spinal atrophy). 5 of the 8 members were examined and found to have myokymia, accentuated by voluntary muscle contraction. Pseudomyotonia was present in 2 patients and, in the 1 patient treated, was abolished by carbamazepine. The association between neuromyotonia and charcto-Marie-Tooth disease has been reported in only 7 patients before but may be more common than previously thought because muscle cramps are reported to be a feature of this disorder.