Study On The Combined Application Of LSR And FrEMG In MVD For Hemifacial Spasm

Objective:To investigate the changes of lateral spread response and free-running electromyography in microvascular decompression in patients with hemifacial spasm and their relationship with decompression effect,clinical prognosis and complications,and possible factors affecting the effectiveness of surgical treatment.Methods:Collect the clinical data of patients with primary hemifacial spasm treated by microvascular decompression under neurophysiological monitoring from January 2021 to December 2021 in the Department of Neurosurgery,Second Hospital of Lanzhou University.LSR monitoring methods:Stimulate the patient’s spasmodic side zygomatic branch,record direct electromyoelectric responses in the orbicularis oculi muscle,and record indirect electromyoelectric responses in the mentalis muscle.The typical LSR waveform was positive when elicits,and the LSR waveform was negative when it did not elicit.According to the disappearance time of LSR,it is divided into disappearance before decompression,disappearance after decompression,and non-disappearance.fr EMG monitoring methods:normal saline was injected in the REZ of the facial nerve before and after decompression,the frequency,amplitude and duration of free-running electromyography was recorded,and it was classified with reference to the Romst（?）ck free-running electromyography model.Statistical analysis:The prognosis was evaluated by referring to the Expert Consensus of Chinese Microvascular decompression for hemifacial spasm in 2014,and the relationship between the disappearance of LSR,the time of disappearance,the duration and waveform type of free-running electromyography,and postoperative efficacy and complications was analyzed,as well as the relationship between fr EMG and LSR.At the same time,the possible factors affecting the effect of surgical treatment were analyzed.Results:LSR monitoring:A total 66 HFS patients were included in this study,51cases（77.27%）were LSR positive and 15 cases（22.73%）were negative.at the end of surgery,LSR disappeared in 49 cases（96.08%）,and 2 cases（3.92%）did not disappear,43 cases（84.3%）recovered immediately after operation,5 cases（9.8%）were significantly relieved,3 cases（5.9%）were partially relieved,and none of them had postoperative inefficiency.All patients were followed up for 3 months after operation,43 cases（84.3%）were cured,7 cases（13.7%）were significantly relieved,and 1 case（2.0%）was partially relieved.There was no significant correlation between LSR disappearance and short-term efficacy（χ~2=3.904,P=0.292）and long-term efficacy（χ~2=3.994,P=0.292）.According to the disappearance time of LSR,18 cases（35.29%）disappeared before decompression,31 cases（60.78%）disappeared after decompression,and 2 cases（3.92%）did not disappear.There was no significant correlation between the time of disappearance of LSR and the short-term efficacy（χ~2=4.435,P=0.363）and the long-term efficacy（χ~2=5.076,P=0.338）.Delayed facial paralysis occurred in 6 cases,which was related to the long course of disease（t=2.036,P=0.046）,but not related to the disappearance of LSR,the degree of spasm,the number of responsible vessels,etc.fr EMG monitoring:A total 31 HFS patients were included in this study,1 case had no free-running electromyography of the mental muscle or orbicularis oculi muscle before and after decompression,and 30 cases had different types of free-running electromyography of the mental muscle or orbicularis oculi muscle before and after decompression.There were 28 cases free-running electromyography of the mental muscle before decompression,5 cases of spike,1 case of burst,12 cases of B train,10cases of C train,and the duration was 144±97.70 seconds;There were 24 cases free-running electromyography of the orbicularis oculi muscle before decompression,6cases of spike,1 case of burst,12 cases of B train,5 cases of C train,and the duration was 89.74±86.60 seconds.There were 30 cases free-running electromyography of the mental muscle after decompression,5 cases of spike,2 cases of burst,14 cases of B train,9 cases of C train,the duration was 125.06±89.39 seconds;There were 25 cases of free-running electromyography of the orbicularis oculi muscle after decompression,3 cases of spike,13 cases of B train,9 cases of C train,the duration was 87.10±70.33seconds.There was no A train in mental muscle and orbicularis oculi muscle before and after decompression.The duration（P>0.05）and waveform type（P>0.05）of free-running electromyography before and after decompression had no significant correlation with the postoperative efficacy.Postoperative delayed facial paralysis occurred in 4 cases,which was related to the C train of orbicularis oculi muscle before decompression（Fisher,P=0.012）.There were 25 LSR positive patients（80.65%）and6 LSR negative patients（19.35%）,The duration of free-running electromyography of mental muscle before decompression was shorter in LSR negative patients（t=2.595,P=0.015）.Conclusion:In HFS patients with MVD,the disappearance of LSR,the time of disappearance,fr EMG duration and waveform type play a limited role in predicting efficacy.However,LSR monitoring is helpful to identify the responsible vessels and indicate whether decompression is sufficient,C train of free-running electromyography of orbicularis oculi muscle appears before decompression,and the longer the preoperative course,the greater the possibility of delayed facial paralysis after surgery.