Abstract: PURPOSE: To explore the feasibility of facial nerve monitoring when using non-depolarizing muscle relaxant cis-atracurium in craniomaxillofacial surgery, and to determine the appropriate degree of muscular relaxation. METHODS: A total of 107 patients with normal preoperative facial nerve function who were planned to undergo elective craniomaxillofacial surgery and needed facial nerve monitoring during operation were selected. Propofol, midazolam, remifentanil and cis-atracurium were used to maintain general anesthesia by total intravenous anesthesia (TIVA). During operation, the surgeons stimulated the facial nerve when TOF%(T4/T1) and T1%(T1/T0) were in different muscular relaxation ranges, while the response and the value of electromyography(EMG) were recorded under different degrees of muscular relaxation. At the same time, the patient's body movement score and the presence of ventilator confrontation were recorded. SPSS 26.0 software package was used to draw the receiver operating characteristic curve (ROC), to determine the best cutoff points for neuromuscular blockade. The relationship between body movement score,ventilation confrontation and different degrees of neuromuscular blockade was analyzed by chi square test. RESULTS: The best cutoff points of TOF% and T1% were obtained: TOF% was 15%, T1% was 35%,and T1% was better than TOF%; when TOF%> 50% and T1%>60%, the patient might have body movement, and the ventilator confrontation increased during operation（P<0.05）. CONCLUSIONS: Facial nerve monitoring can be effectively performed under partial neuromuscular blockade of cis-atracurium in general anesthesia. The recommended range of muscle relaxation is 15%-50% for TOF% and 35%-60% for T1%.

Key words: Facial nerve monitoring, Cis-atracurium, Partial muscular relaxation, Muscle relaxation monitoring, Total intravenous anesthesia