To the Editor.—
The report by Medina et al (Arch Neurol 33:587, 1976) of myokymia resulting from peripheral nerve injury merits further comment. I have never been confident of a qualitative distinction between fasciculation and myokymia. If one acknowledges that they possess some essential characteristics in common, and thus might represent different parts of a spectrum of involuntary motor unit activity, then a better example to indicate a peripheral origin of such motor unit activity is the case reported by Harvey and Kuffler1 in which fasciculation activity occurred after completenerve transection was verified surgically.The case described by Medina and co-workers contains an unknown factor: the integrity of the spinal cord. Why should myokymia have occurred in that patient when in thousands of comparable nerve injuries there is no such motor unit activity? Perhaps their patient had unusual irritation of sensory fibers, which caused discharge of spinal motor neurons