Intraoperative Monitoring Of Abnormal Muscle Response Research Articles

Intraoperative findings of abnormal muscle response for hemifacial spasm following botulinum neurotoxin treatment.

This study aimed to investigate the effect of preoperative botulinum toxin (BTX) injection on intraoperative abnormal muscle response (AMR) in patients with hemifacial spasm (HFS). A total of 104 patients (32 men, 72 women) who underwent microvascular decompression (MVD) for HFS were included in this study. A total of 62 patients without and 42 patients with preoperative BTX treatments were assigned to group A and group B, respectively. AMR recordings were obtained from the orbicularis oculi and mentalis muscles by stimulation of the marginal mandibular branch and zygomatic branch of the facial nerve, respectively. The intraoperative AMR monitoring findings and therapeutic effects were compared between groups A and B. The rates of the patients with unavailable AMRs recorded from the orbicularis oculi muscles in group B (38.1%) were significantly higher than those in group A (14.5%, p = 0.006). Moreover, in cases with over 4 times BTX injection, the recordings of AMR from the orbicularis oculi muscles were poorer than the cases with less BTX injection (p = 0.001). There were no significant differences in the rates of the patients with unavailable AMRs recorded from the mentalis muscles between the two groups. There were no significant differences in the surgical results obtained between the two groups. Preoperative BTX injections should be less than 4 times to ensure effective AMR monitoring. MVD using AMR monitoring is useful for patients with HFS who were previously treated by BTX as well as those who were not treated.

The Effects of Combined Intraoperative Monitoring of Abnormal Muscle Response and Z-L Response for Hemifacial Spasm.

Microvascular decompression (MVD) is the most effective treatment for hemifacial spasm (HFS). During MVD surgery, abnormal muscle response (AMR) is widely used. Z-L response (ZLR) is a new monitoring method for HFS. We compared the effectiveness of AMR plus ZLR and simple AMR. In a retrospective study of 1868 cases of HFS treated using intraoperative monitoring between January 2013 and December 2015, 896 patients underwent simple AMR monitoring and 972 underwent combined intraoperative monitoring of AMR and ZLR. AMR waveforms were observed in 837 (93.42%) patients in the AMR group and in 898 (92.39%) patients in the AMR plus ZLR group (P > 0.05). During MVD, AMR waveforms disappeared in 772 patients in the AMR group and 854 patients in the AMR plus ZLR group (P < 0.05). The efficacy rate of MVD in the AMR plus ZLR group was higher compared with the AMR group when AMR was not detected or disappeared during the operation (P < 0.05). When AMR persisted during the operation, there was no significant difference between the 2 groups in efficacy of the operation (P > 0.05). Regardless of whether the compression vessels of the facial nerve are simple or complicated, combined intraoperative monitoring of AMR plus ZLR monitoring provides more valuable neurosurgical guidance than simple AMR during MVD for HFS.

The role of abnormal muscle response monitoring during microvascular decompression for treating hemifacial spasm

Objective To investigate the significance of abnormal muscle response (AMR) monitoring during microvascular decompression (MVD) for hemifacial spasm (HFS) in confirming the responsible blood vessel, improving the prognosis and reducing postoperative complications. Methods A total of 34 HFS patients underwent AMR monitoring during MVD. Results The AMR of mentalis was recorded in all 34 patients by electrically stimulating zygomatic branch of facial nerve before anesthesia. Compared with preoperation, the AMR latency after operation was significantly longer [(16.12 ± 3.17) ms vs (14.75 ± 3.32) ms, P = 0.015] and amplitude was significantly reduced [(0.11 ± 0.03）mV vs (0.13 ± 0.03) mV, P = 0.027]. AMR was disappeared in 32 cases (94.12% ) after the removal of responsible blood vessel. There was one patient (2.94%) whose AMR disappeared momentarily after the incision of endocranium and disappeared completely after the removal of responsible blood vessel, while AMR still existed in one case (2.94%) after the removal of responsible blood vessel. Responsible blood vessels included anterior inferior cerebellar artery (N = 30, 88.24%), posterior inferior cerebellar artery (N = 3, 8.82%) and basilar artery (N = 1, 2.94%), which oppressed the root of facial nerve (N = 22, 64.71%), the distal part (N = 8, 23.53%), and both the root and distal part (N = 4, 11.76%). After operation, facial spasm disappeared. Thirty-one cases were cured, 2 cases evidently remitted, and one case inefficacious. The total effective rate was 97.06%. Conclusions Continuously intraoperative monitoring of AMR contributes to confirming the responsible blood vessel, completing decompression for facial nerve more thoroughly, improving the prognosis, reducing delayed healing up, at the same time enhancing neurosurgeons' confidence and reducing operation time. DOI: 10.3969/j.issn.1672-6731.2016.05.010

Management of vessels passing through the facial nerve in the treatment of hemifacial spasm.

In hemifacial spasm, it is extremely rare to find a vessel passing through the facial nerve. In this study, we present our experience of the surgical treatment of four such patients. From January 2010 to Match 2015, we treated 2,576 hemifacial spasm patients with microvascular decompression in our department. Of these, four had an intraneural vessel. Intraoperative findings and treatment were recorded, and postoperative outcomes were analyzed. In three patients, the intraneural vessel was the anterior inferior cerebellar artery, which we wrapped with small pieces of wet gelatin and Teflon sponge. A small vein found in the fourth patient was treated with facial nerve combing. Complete decompression was achieved and abnormal muscle response disappeared. Three patients got an excellent result and one patient got a good result. One patient had postoperative facial paralysis, which improved over 10 months of follow-up. If an artery passes through the facial nerve, it can be decompressed by wrapping the vessel with wet gelatin and Teflon sponge. If a vein passes through the facial nerve, combing can be used. Intraoperative abnormal muscle response monitoring is very helpful in achieving complete decompression.

Prognostic value of intra-operative abnormal muscle response monitoring during microvascular decompression for long-term outcome of hemifacial spasm

The reliability of intra-operative abnormal muscle response (AMR) monitoring as an indicator of post-operative outcome in patients with hemifacial spasm (HFS) is under debate. The primary aim of this study was to evaluate the correlation between intra-operative AMR changes and long-term post-operative outcome. We monitored intra-operative AMR during microvascular decompression (MVD) in consecutive patients with HFS ( n = 104). Patients in this study were divided into two groups based on whether their AMR disappeared or persisted following MVD. Ninety patients were followed-up, and the mean duration from surgery to final follow-up examination was 3.7 years. Fourteen patients were lost to follow-up. AMR disappeared during surgery for 80 patients; of these, 74 achieved complete resolution of HFS, five had persistent HFS, and one patient developed a recurrence of HFS. Of the 10 patients with persistent AMR despite effective MVD, eight patients achieved complete resolution, one patient had persistent HFS, and one developed recurrent HFS. The long-term clinical outcome of HFS after MVD did not significantly correlate with intra-operative AMR changes ( p = 0.791). Therefore, we suggest that intra-operative AMR monitoring may not be a reliable indicator of long-term post-operative outcome for HFS.

The value of abnormal muscle response monitoring during microvascular decompression surgery for hemifacial spasm

Objective Abnormal muscle response(AMR) to the electrical stimulation of a branch of facial nerve is a specific electrophysiological feature of primary hemifacial spasm ( HFS ).Although the correlation between intraoperative AMR findings and postoperative results in patients with HFS has been investigated before,the AMR monitoring has not been employed widely during the microvascular decompression(MVD) surgery.The aim of this study was to evaluate the value of AMR monitoring during MVD,and the correlation between the AMR changes and the clinical outcome.Method This study included 241 cases of MVD.Intraoperative AMR monitoring was performed for each subject.The patients were divided into two groups based on whether the AMR wave disappeared or not following decompression of the facial nerve.Results The AMR disappeared after MVD in 175 patients.Among these 175 patients,165 (94.3％ ) patients were relieved from HFS 1 week after HFS.Out of the 66 patients in whom the AMR persisted after MVD,52 (78.8％ ) patients were relieved.The correlation between intraoperative AMR abolition and HFS relief was statistically significant ( P ＜ 0.05 ).Conclusions Intraoperative AMR monitoring is an effective assistant for a successful MVD for the patient with HFS.It may be helpful in predicting outcomes in short term and identifying offending vessels,so it should be monitored routinely during MVD. Key words: Abnormal muscle response ; Hemifacial spasm ; Microvascular decompression ;

The value of abnormal muscle response monitoring during microvascular decompression surgery for hemifacial spasm

Background and objectives Abnormal muscle response (AMR) to the electrical stimulation of a branch of facial nerve is a specific electrophysiological feature of primary hemifacial spasm (HFS). The aim of this study was to evaluate the value of AMR monitoring during microvascular decompression surgery (MVD), and the correlation between the AMR changes and the clinical outcomes. Methods This study included 241 cases of MVDs. Intraoperative AMR monitoring was performed for each subject. The patients were divided into two groups based on whether the AMR-disappeared or not following decompression of the facial nerve. Results Postoperatively, 229 (95.0%) patients were relieved from the spasm, 215 (93.9%) occurred in the AMR-disappeared group, 14 (6.1%) in the non-AMR-disappeared group. The correlation between intraoperative AMR abolition and HFS relief was statistically significant. Conclusions Intraoperative AMR monitoring was an effective assistant for a successful MVD for the patient with HFS. It is worth being routinely employed during the operation.

Re-operation for persistent hemifacial spasm after microvascular decompression with the aid of intraoperative monitoring of abnormal muscle response

Microvascular decompression (MVD) is the only solution that can effectively control hemifacial spasm (HFS). Regarding treatment of the patients who failed the first operation, it is still controversial. We tried to evaluate the safety and efficiency of the early re-exploration for such kinds of patients. Thirteen patients failed the first MVD and received a second MVD procedure. The spasm was not resolved at all or became even more severe after the first MVD. Abnormal muscle response (AMR) persisted during the first MVD operation or disappeared once but emerged again. The patient had a strong will to do the re-operation and was aware of the high risks of operative complications. All the 13 patients got good or excellent spasm resolution immediately after the re-operation, which involved whole-range exploration and intraoperative AMR monitoring; however, there were two cases (15.4%) of permanent facial weakness and three cases (23.0%) of transient facial weakness. Our experience on early repeat MVD is whole-range exploration and intraoperative AMR monitoring; in other words, re-operation cannot rely too much on experience.

Abnormal muscle response monitoring during microvascular decompression for hemifacial spasm

Several studies have investigated the relation between intraoperative abnormal muscle response (AMR) findings and postoperative results in patients undergoing microvascular decompression (MVD) for hemifacial spasm (HFS). However, there is some debate over the reliability of AMR as an indicator of postoperative outcome. We investigated whether AMR findings obtained during MVD reflect postoperative outcome in patients with HFS. Subjects were 60 HFS patients who underwent AMR monitoring during MVD. AMR recordings were obtained from the mentalis muscle by electrical stimulation of the temporal branch of the facial nerve and from the orbicularis oculi muscles by stimulation of the marginal mandibular branch. Surgical outcome was compared with AMR findings at the completion of MVD. Mean follow-up was 61 months. HFS resolved completely in 50 patients in whom AMR disappeared intraoperatively and in 5 patients in whom the AMR amplitude was decreased at the end of MVD. Four patients showed HFS at the final follow-up examination despite cessation or decrease of AMR during surgery. In 1 patient, preoperative AMR waveforms persisted throughout MVD, but the postoperative outcome was excellent. Our findings suggest that intraoperative cessation or decreased amplitude of AMR at the end of surgery indicates a high likelihood of postoperative relief of HFS. We believe that intraoperative AMR monitoring is useful in MVD surgery for HFS.