Somatosensory evoked potentials during whole body hyperthermia in humans

Somatosensory evoked potentials (SEPs) and body temperature were recorded in patients subjected to induced total hyperthermia for treatment of advanced neoplasms. Elevation of body temperature up to 42 degrees C for 2 h was achieved using a computer-controlled external heating system. SEPs were recorded continuously on-line during the treatment using finger shock stimulation. Evoked potential components later than 160 msec disappeared in the early part of the treatment, but reappeared quickly during cooling. P50 and P50-N70 amplitudes decreased regularly and significantly over the whole duration of the heating period. During the plateau period, no evoked potential peaks could be detected but short latency peaks reappeared as soon as cooling started. The disappearance of SEPs to finger stimulation during sustained hyperthermia at 42 degrees C confirms the findings obtained by EEG recording that a major neuronal dysfunction occurs under these circumstances which subsides quickly as temperature is dropped.