The Effects of Depth of Anesthesia on Muscle-Recorded Motor Evoked Potentials: A Prospective Observational Study

Our findings challenge some commonly held beliefs. First, our findings suggest that deeper anesthesia has differential effects on the different muscle groups, with little effect on the hand muscles. The current practice of using the hand signals as reference values during procedures below C8/T1 may therefore need re-evaluation. Second, the paucity of effect of depth of anesthesia on Tc-mMEP thresholds and latencies suggests that Tc-mMEP generation is not influenced by deep anesthesia in a clinically relevant way. Therefore, the threshold level monitoring method may provide a more reliable indicator of motor pathway integrity during surgery. This could reduce the likelihood of false-positive warnings and unnecessary interventions.