BACKGROUND

We compared the effect of propofol and sevoflurane combined with remifentanil under comparable bispectral index (BIS) levels on transcranial electric motor-evoked potentials (TceMEPs) and somatosensory-evoked potentials (SSEPs) during brainstem surgery.

MATERIALS AND METHODS

A total of 40 consecutive patients (20 per group) undergoing brainstem surgery were randomly assigned to 2 groups receiving either 0.5 MAC sevoflurane or propofol at an effect-site concentration of 2.5 µg/mL for maintenance of anesthesia. Remifentanil was administered to both groups at a rate of 0.25 to 0.35 μg/kg/min along with cisatracurium (0.03 to 0.04 mg/kg/h). TceMEP recordings were carried out in the abductor pollicis brevis, abductor hallucis, and tibialis anterior muscles, whereas cortical SSEPs were measured with posterior tibial nerve stimulation. Amplitudes and latencies of TceMEPs and SSEPs were recorded at 1, 2, 3, and 4 hours after the induction of anesthesia.

RESULTS

BIS values remained in the 45 to 60 range. Amplitudes of TceMEPs were significantly higher in the propofol group than those in the sevoflurane group (P<0.05, at all study time points in abductor pollicis brevis and abductor hallucis muscles and only 4 h after anesthetic induction for tibialis anterior muscle), whereas latencies were shorter in the propofol group than those in the sevoflurane group (P<0.05). No differences were observed in latency and amplitude while recording SSEPs between the 2 anesthetic techniques. None of the patients had TceMEPs and SSEPs amplitude or latency changes, exceeding our set limit.

CONCLUSIONS

Both sevoflurane and propofol at low dosages combined with remifentanil under comparable BIS values and partial muscle relaxation can be used when monitoring of TceMEPs and SSEPs is required for brainstem surgery.