Application of abnormal muscle response and Z⁃L response combined monitoring during keyhole microvascular decompression of hemifacial spasm

Objective To compare the monitoring effect of abnormal muscle response (AMR) combined Z ⁃ L response (ZLR) and simple AMR in keyhole microvascular decompression (MVD) for hemifacial spasm (HFS). Methods Total 258 patients with primary HFS treated with keyhole MVD between January 2014 and April 2024 from The Second Affiliated Hospital of Soochow University were analyzed retrospectively, including 102 patients underwent simple AMR (ARM group) and 156 patients underwent intraoperative monitoring of AMR combined ZLR (AMR + ZLR group). Calculate the surgical efficiency, and record the occurrence of postoperative complications. Results In the AMR + ZLR group, 145 cases recovered 7 d after surgery, 11 cases were ineffective, and the surgery effective rate was 92.95% (145/156); 151 cases recovered 6 months after surgery, 5 cases was ineffective, and the surgery effective rate was 96.79% (151/156). In the AMR group, 86 cases recovered at 7 d after surgery, 16 cases were ineffective, and the surgery effective rate was 84.31% (86/102); 92 cases recovered 6 months after surgery, 10 cases were ineffective (2 cases relapsed), and the surgery effective rate was 90.20% (92/102). The MVD effective rates in AMR + ZLR group were better than that in AMR group at 7 d and 6 months after surgery (χ2 = 4.908，P = 0.027; χ2 = 4.904，P = 0.027). On the first day after surgery, 12 cases in the AMR + ZLR group experienced mild facial paralysis, which recovered within 7 d after surgery. In the AMR group, one case had tinnitus and one case had dizziness, both of which recovered within 3 d after surgery, 18 cases experienced mild facial paralysis, which recovered within 7 d after surgery. Conclusions Intraoperative monitoring of AMR combined ZLR provides more valuable neurosurgical guidance than simple AMR during MVD for HFS. MVD is an effective method for the treatment of HFS, and the MVD rate of keyhole in our center has maintained a high level.