ABSTRACT
Objective To investigate the effects of tetanic stimulation of peripheral nerve on intracranial direct electrical stimulation motor-evoked potentials (MEP) in patients undergoing cerebral functional area operation. Methods Eight patients undergoing elective brain tumor resection under propofol-fentanyl anesthesia with partial neuromuscular blockade were enrolled in the study. Both conventional MEP (C-MEP) monitoring and posttetanic MEP (P-MEP) monitoring were performed throughout the operation for each patient, and the two groups of data were recorded. For one group, direct electrical stimulation with a train of five pulses was delivered to motor cortex and pyramidal tract, C-MEP was unilaterally recorded from the abductor pollicis brevis, and P-MEP was obtained 1 s after tetanic stimulation (frequency 50 Hz, intensity 50 mA, duration 5 s) to the ipsilateral tibial nerve.For the other group, direct electrical stimulation with a train of five pulses was delivered to motor cortex and pyramidal tract, C-MEP was unilaterally recorded from the tibialis anterior, and P-MEP was obtained 1 s after tetanic stimulation (frequency 50 Hz, intensity 50 mA and duration 5 s) to the contralateral tibial nerve. Randomized crossover method was used for C-MEP and P-MEP recording in each group, with an interval of 120 s. The adverse effects were observed. Results Amplitudes of P-MEP from the abductor pollicis brevis and tibialis anterior were significantly higher than those of C-MEP. Three patients had body movement during intraoperative cortex stimulation, while there was no awareness during operation and other electrical stimulation-related nervous system impairment and complications. Conclusion The application of tetanic stimulation of peripheral nerve before direct electrical stimulation can augnent the amplitudes of MEP from the abductor pollicis brevis and tibialis anterior in patients undergoing cerebral functional area operation.