The Combined Intraoperative Monitoring Of Abnormal Muscle Response(AMR) And Z-L Response(ZLR) During Microvascular Decompression Of Hemifacial Spasm

ObjectiveTo investigate the significance and efficacy of combined intraoperative abnormal muscle response(AMR)and Z-L response(ZLR)monitoring during microvascular decompression(MVD)surgery in patients with hemifacial spasm(HFS).MethodWe retrospectively analyzed 21 patients(8 males and 13 females)of HFS who underwent combined AMR and ZLR intraoperative monitoring assisted MVD surgery in the neurosurgery department in Anhui Provincial Hospital from Jan of 2018 to Jan of 2019.During operation,the temporal branch and the marginal mandibular branch were electrically stimulated to elicit AMR at the time point when muscle relaxant was metabolized,and at craniotomy,dura opening,cerebral spinal fluid release,vessel decompression,and at dura suturing.Stimulation intensity were recorded.And ZLR were elicited at any suspected culprit vessels before and after the decompression.Result19 of the total 21 patients showed immediate disappearance of HFS,1 patient showed partial release of spasm symptom,1 patient got symptom relapse and the spasm was complete release after 1-week post-surgery.The response rate was significantly higher than the overall response rate of MVD for facial spasm(85-93%,including 86%immediate response rate).The response rate was significantly higher than the overall response rate of MVD for facial spasm(85-93%,including 86%immediate response rate).All 21 patients with hemifacial spasm successfully induced AMR wave and ZLR before decompression,while only 1 patient did not induce AMR wave of the orbicularis oculi muscle of the same side when the facial nerve ramus of the mandibular margin was stimulated.Before decompression,craniotomy,dural incision and other operations did not have a clear impact on AMR,while opening the cisterna and releasing cerebrospinal fluid from the arachnoid space made AMR completely disappear in one patient,and AMR threshold intensity in some patients showed a certain increase trend.Microscope to confirm Teflon pads responsibility after blood vessels,10 cases with AMR,ZLR instantly disappeared,1 case of patients waiting for 23 minutes after AMR,ZLR completely disappear at the same time,1 case of patients under reduced pressure anterior artery,anterior inferior cerebellar artery,AICA)appear only after mandibular branch of AMR disappear,but the temporal AMR,ZLR persist,after further relief suspicious AICA wear branch artery,temporal AMR and ZLR waveform disappear.In addition,a total of 9 patients(42.9%)had persistent AMR,with only partial disappearance or increased threshold intensity and decreased amplitude,among which 2 patients(0.9%)had persistent ZLR.Another patient(0.5%)was confirmed to have sufficient decompression under the microscope and no other suspected responsible vessels were found,but ZLR persisted and AMR disappeared.There was no significant statistical difference between the persistence of AMR wave and ZLR after facial nerve microvessels were fully decompressed.ConclusionIntraoperative monitoring of AMR or ZLR alone has certain limitations.When AMR cannot be induced due to the influence of other surgical operations,or when AMR persists and adequate decompression of responsible vessels cannot be confirmed under the microscope,combined monitoring of AMR and ZLR can provide more reliable information for intraoperative determination of responsible vessels and improvement of decompression success rate?...