[Congenital neuromyotonia. Retrospective study of 4 cases]

Fasciculation, double discharge, myokymia and neuromyotonia are different kinds of involuntary muscular activity that originate in ectopic discharges of the motor axons. Electrophysiological studies are needed in all cases for the diagnosis. Non rigorous electrophysiological studies in some cases is the cause of the historically unclear nosological delimitation of the neuromyotonic syndromes.

To report the clinical picture and electrophysiological findings in patients with congenital neuromyotonia.

Four patients with congenital neuromyotonia were studied. Electrophysiological exam included nerve conduction measurements, study of the after-discharges and conventional EMG. Spontaneous discharges were displayed after applying a low pass filter, signal trigger and delay line.

In one case positive motor features predominate (continuous muscle fiber activity). On the contrary, two cases, showed neuropathic deficitary signs with a Charcot-Marie-Tooth type II disease phenotype; neuromyotonia was, in both cases, an electrophysiological feature. In the last patient, motor signs were limited to the facial muscles but electrophysiological study discovered generalized neuromyotonia. Treatment with carbamazepine or oxcarbazepine was useful in the four cases.

Congenital neuromyotonia is a clinically heterogeneous syndrome with uniform electrophysiological features that permit its qualification.