Clinical study on intraoperative facial nerve motor evoked potentials monitoring under partial neuromuscular blockade

Abstract

Objective To find optimal partial neuromuscular blockade used for intraoperative facial nerve motor evoked potential (FNMEP) monitoring and its feasibility for application in patients undergoing acoustic neuroma resection.Methods Two parties were included: the amplitude and latency of FNMEP and electrical stimulation-induced body movement scores were recorded under various degree of neuromuscular blockade in thirty neurosurgical patients.After the optimal partial neuromuscular blockade was obtained,intraoperative FNMEP monitoring was performed in fifteen patients undergoing acoustic neuroma resection .The sensitivity and specificity of FNMEP were analyzed according to postoperative/preoperative amplitude of FNMEP and postoperative facial nerve function.Results The FNMEP waveforms were discernible and less electrical stimulation induced body movement was observed when T1 =30%～40% was used.Fifteen patients were monitored successfully with FNMEP.And the sensitivity and specificity of postoperative/preoperative FNMEP amplitude ratio to predict postoperative facial nerve function were 90% and 91% respectively.Conclusions T1=30%～40% is optimal partial neuromuscular blockade used for intraoperative FNMEP monitoring and FNMEP monitoring under such partial neuromuscular block is feasible and reliable. Key words: Facial nerve; Motor evoked potentials; Intraoperative monitoring; Craniotomy; Partial neuromuscular block