Objective:To explore the evaluation value of abnormal muscle response (AMR) monitoring in efficacy of microvascular decompression in primary hemifacial spasm.Methods:A retrospective study was performed. Sixty-four patients with primary hemifacial spasm, admitted to our hospital from April 2019 to December 2020, were chosen. All patients underwent intraoperative AMR monitoring and were divided into AMR complete-disappeared group, AMR significant-changed group and AMR not significant-changed group according to the monitoring results. The relief of spasticity symptoms among the three groups was observed one week and one year after surgery. The specificity and sensitivity of AMR monitoring in evaluating the efficacy, the relations between intraoperative AMR changes and postoperative efficacy after microvascular decompression were analyzed.Results:The specificity and sensitivity of AMR monitoring in predicting spasmodic relief after microvascular decompression were 89.7% and 66.7%, respectively, at one week, and 86.7% and 50.0%, respectively, at one year. There were statistical differences in clinical remission rate one week after microvascular decompression among AMR complete-disappeared group ( n=46), AMR significant-changed group ( n=8) and AMR not significant-changed group ( n=10, P<0.05); there were no significant differences in clinical remission rate one year after microvascular decompression among the three groups ( P>0.05). There was no significant difference in clinical remission rate one week and one year after microvascular decompression between patients having AMR complete disappearance before Teflon and patients having AMR complete disappearance after Teflon ( P>0.05). Conclusion:AMR monitoring has high specificity but modest sensitivity in predicting spasmodic relief after microvascular decompression; intraoperative AMR disappearance is associated with short-term efficacy, but it is not a reliable indicator for long-term efficacy; the time of disappearance of intraoperative AMR has no guiding significance in judging the efficacy of patients with primary hemifacial spasm.