Discharge patterns of spontaneous activity and motor units on concentric needle electromyography

We analyzed discharge patterns in electromyograms of 6 patients with complete nerve lesions and of 26 healthy subjects, in order to better differentiate between pathological and physiological spontaneous electromyographic (EMG) activity. Within 1639 trains of action potentials, the intervals between at least five successive discharges were measured. Discharge regularity was evaluated with three different algorithms. At 99% specificity, an abnormal discharge pattern was identified with 91 to 95% sensitivity, depending on the algorithm used. Analysis of as few as four successive interdischarge intervals allowed reliable differentiation between normal and pathological spontaneous EMG activity. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 123–126, 2001