Purpose: We studied neuromuscular block at the orbicularis oris, corrugator supercilii, and adductor pollicis muscles in anesthetized patients.
Methods: Fifty-four adult patients undergoing air-oxygen-sevoflurane-fentanyl and epidural anesthesia were randomly divided into orbicularis oris, corrugator supercilii, and adductor pollicis groups of 18 patients each. In the three groups, the degree of neuromuscular block caused by rocuronium 0.6 mg/kg was monitored at the orbicularis oris, corrugator supercilii, and adductor pollicis muscles acceleromyographically.
Results: Onset of neuromuscular block did not significantly differ among the three groups [157 ± 60, 186 ± 73, and 148 ± 45 s; mean ± standard deviation (SD)]. Minimum value of 1st stimulation in train-of-four (T1)/control at the corrugator supercilii group was significantly higher than in the orbicularis oris and adductor pollicis groups (0.108 ± 0.066 vs. 0.021 ± 0.024 and 0.002 ± 0.007; P < 0.001). T1/control at the orbicularis oris group was significantly higher than at the adductor pollicis group 30 min after rocuronium (P < 0.05). T1/control at the corrugator supercilii group was significantly higher than at the orbicularis oris and adductor pollicis groups 10-30 and 10-40 min, respectively, after rocuronium (P < 0.05). Train-of-four ratios at the orbicularis oris and corrugator supercilii groups were significantly higher than at the adductor pollicis group 40-120 min after rocuronium (P < 0.05).
Conclusion: The corrugator supercilii muscle is more resistant to rocuronium than the orbicularis oris and adductor pollicis muscles. Recovery of neuromuscular block at the orbicularis oris muscle is slower than that at the corrugator supercilii muscle but was faster than that at the adductor pollicis muscle.