NERVE, MUSCLE, AND NEUROMUSCULAR-JUNCTION ELECTROPHYSIOLOGY AT HIGH-TEMPERATURE

Although the effect of low temperature on the peripheral nervous syste m has been systematically studied, the effect of high temperature has not. We investigated the effect of elevating limb temperature from 32 degrees C to 42 degrees C by performing sequential motor studies, anti dromic sensory studies, and 3-Hz repetitive stimulation in normal subj ects. In addition, we recorded single motor units by using threshold s timulation. On average, motor amplitude and duration decreased by 27% and 19%, respectively, whereas sensory amplitude and duration decrease d by 50% and 26%, respectively. Neuromuscular transmission remained no rmal at 42 degrees C. Single motor unit recordings revealed a reductio n in amplitude of 26%, similar to the overall reduction in compound mo tor amplitude. These findings demonstrate that significant reductions in sensory and motor amplitudes can occur in normal nerves at high tem perature; we hypothesize that these changes are secondary to alteratio ns in nerve and muscle ion channel function. (C) 1997 John Wiley & Son s, Inc.