Detection of somatic muscle fasciculation on electrocardiograms.

Small discrete spikes appearing on the electrocardiogram (ECG) of a man with a pacemaker turned out to be fasciculation potentials picked up from leg muscles. To find out how common these spikes were all routine ECGs made in one month were reviewed. Spike potentials were found in six patients, and in each case they originated from somatic musculature. Spikes could nearly always be detected on ECGs that were recorded subsequently in patients known to have lower motor neurone lesions that produced fasciculation. Thus the presence of these fasciculation spikes may suggest underlying neuromuscular disease; this possibility should be recognised by those who record ECGs so that the spikes are not suppressed by overuse of the filter.