This study was designed to evaluate firing rate variability in patients with upper/lower motor neuron disorders. Twenty healthy subjects and 19 patients with motor neuron disorders participated in the study. Consecutive motor unit action potential pairs from extensor digitorum communis (EDC) muscle were recorded from each subject with trigger-delay line mode. Patients with motor neuron disorders (17.7 ± 10.8 ms) showed significantly higher mean time variability of interpotential interval value than healthy volunteers (10.3 ± 0.1 ms) (p < 0.001).
Keywords: ALS; LMN; firing rate variability; interpotential intervals; motor neuron diseases; motor unit firing characteristics.