Effects of altering core body temperature on somatosensory and motor evoked potentials in rats.

The effects of core temperature on three potentials--somatosensory spinal evoked potential, somatosensory cortical evoked potential, and spinal motor evoked potential--were studied in rats. Hyperthermia reduced the latency and increased the conduction velocity of all three potentials. Somatosensory spinal evoked potential amplitude was unchanged, whereas somatosensory cortical and spinal motor evoked potentials deteriorated above 42 C. Hypothermia increased latency and decreased conduction velocity in all three potentials. The amplitude of the spinal motor evoked potential decreased, and the somatosensory cortical and spinal motor evoked potentials disappeared below 28 C. Hyperthermia and hypothermia caused significant changes in the latency of all three potentials. The latency change of all three potentials became significant at 2-2.5 C above or below baseline, suggesting a range within which evoked potential studies should be performed.