SINGLE-FIBER ELECTROMYOGRAPHY, NERVE-CONDUCTION STUDIES, AND CONVENTIONAL ELECTROMYOGRAPHY IN PATIENTS WITH CRITICAL-ILLNESS POLYNEUROPATHY- EVIDENCE FOR A LESION OF TERMINAL MOTOR AXONS

Nine patients at risk for critical illness polyneuropathy (CIP) were i ncluded in a prospective study. We performed nerve conduction studies, electromyography, and a stimulation single-fiber electromyography (SF EMG). Five of 9 patients were diagnosed as CIP because they developed abnormal spontaneous activity during the follow-up period. Their SFEMG revealed a significant increase in mean jitter (25%, P < 0.005). In 4 patients without abnormal spontaneous activity there was no significa nt increase in the mean jitter, although 1 of the latter 4 patients sh owed an increased jitter, indicating that abnormal SFEMG may precede a bnormal spontaneous activity. Nerve conduction studies did not show an y significant changes in both patient groups. Our findings suggest tha t CIP is a primarily axonal motor neuropathy. The increased jitter in patients with CIP indicates that CIP is a primarily axonal neuropathy with a lesion of terminal motor axons. (C) 1997 John Wiley & Sons, Inc .