The evaluation of compartmental syndromes using somatosensory evoked potentials in monkeys

Somatosensory evoked potentials (SEPs) of the median, deep peroneal, and tibial nerves were recorded in experimentally induced compartmental syndromes in nine Macaca mulatta monkeys. A total of 17 trials were performed at the following mean pressure levels: 17, 30, 36, and 40 mm Hg. Evoked potentials were recorded using a four-channel evoked response system. Significant changes in SEP waveforms (greater than 3-millisecond increases in N1 or P1 latencies, or a 50% decrease in wave amplitudes in the presence of normal contralateral waveforms) were seen at pressures as low as 30 mm Hg as early as 45 minutes. Pressures of 35 and 40 mm Hg led to more pronounced abnormalities in SEP waveforms, with marked decreases in wave amplitudes and variability in the time to onset of these changes. Somatosensory evoked potentials are noninvasive, sensitive, and dynamic determinations of nerve function and may have clinical significance in the early detection of nerve dysfunction in compartment syndromes.