Abnormal Muscle Response Research Articles

Hypertension and Diabetes Are Associated With Clinical Characteristics in Patients Undergoing Microvascular Decompression for Hemifacial Spasm.

The aim of the present study is to investigate effect of hypertension and diabetes on neuroelectrophysiology, outcomes and complications in patients with hemifacial spasm (HFS) treated by microvascular decompression (MVD). From June 2014 to December 2016, 476 consecutive HFS patients who had undergone MVD were divided into 2 groups according to the presence or absence of comorbidities: diabetic group (n = 26) versus non-diabetic group (n = 450), and hypertensive group (n = 141) versus normotensive group (n = 335). Relevant patient data, including preoperative and postoperative neuroelectrophysiology, operative findings, outcome of MVD and complications, were collected and analyzed retrospectively over the 2-year follow-up period. The impact of hypertension and diabetes on the clinical features of HFS patients was investigated by using logistic regression models. Brainstem auditory evoked potential (BAEP), postoperative prognosis and abnormal muscle response (AMR) were not different between any of the 2 groups. Preoperative positive AMR occurred more frequently in the nondiabetic group than diabetic group [OR = 0.202, P = 0.004], whereas hypertension was not independently predictive for neuroelectrophysiology in patients with HFS. Adjusted multivariate analysis indicated that hypertension was the only clinical factor associated with MVD-related complications [OR = 0.482, P = 0.007] and hearing impairment [OR = 0.28, P = 0.004] after various potential confounders were taken into account, whereas diabetes was not predictive for postoperative complications. Diabetes is associated with low positive rate of preoperative AMR, thus weakening the predictive role of AMR for successful MVD. Hypertension may be an independent risk factor for hearing impairment after MVD.

An Intraoperative Multibranch Abnormal Muscle Response Monitoring Method During Microvascular Decompression for Hemifacial Spasm

Intraoperative abnormal muscle response (AMR) is widely used as an indicator during microvascular decompression surgery for hemifacial spasm. Usually only 1 muscle is recorded, and not all patients show a response, leaving the surgery somewhat blinded. We propose an improved method to record from multiple muscles innervated by multiple branches of thefacial nerve to increase the positive AMR detection rate. Retrospective analysis was performed of 1604 patients with hemifacial spasm undergoing microvascular decompression at a single center. All patients were monitored for AMR by stimulating the zygomatic branch of the facial nerve. Only mentalis was recorded in 158 cases (single-branch AMR). Orbicularis oris, frontalis, and mentalis were simultaneously monitored in 148 cases (3-branch AMR), and platysma was further added in the remaining 1298 cases (4-branch AMR). Positive AMR detection rates were compared across the groups. Total positive AMR detection rates significantly increased as more muscles were included in monitoring and were 74.1% for single-branch AMR, 86.5% for 3-branch AMR, and 98.4% for 4-branch AMR. Detection rates from single muscles were not significantly different across the groups. For all available cases, rates were 73.5% from mentalis, 47.2% from frontalis, 64.1% from orbicularis oris, and 40.8% from platysma. This new multibranch AMR monitoring method can effectively increase the positive detection rate to as high as 98.4%. It is expected to better assist surgery.

Clinical Research on Delayed Cure after Microvascular Decompression for Hemifacial Spasm.

The clinical data of patients with hemifacial spasm (HFS) were analyzed statistically to identify factors leading to delayed cure after microvascular decompression (MVD). A retrospective analysis of the clinical data of 600 patients with HFS subjected to MVD from March 2016 to May 2018 was performed. Student t test, chi-square test, logistic regression analysis, and multivariate analysis of variance were used to analyze the correlation between delayed cure and its related factors. Among the 600 patients enrolled, 117 had delayed cure after MVD. The shortest duration of delayed cure was 4 days, and the longest was 540 days, with an average of 108 days. The frequency of delayed improvement in these patients was not associated with sex, age, or offending vessel type (p > 0.05); however, delayed cure was positively correlated with the course of the disease, grade of HFS severity, and disappearance of abnormal muscle responses during the operation (p < 0.05). Moreover, a longer disease course was associated with more severe related symptoms and a longer duration of postoperative delayed cure. MVD is an effective treatment for HFS. Given that postoperative delayed cure was unavoidable, even with accurate identification of the offending vessel and sufficient decompression of the root exit zone, delayed cure should be considered in patients undergoing reoperation due to lack of remission or relapse after the operation. Additionally, the timing of efficacy assessments should be delayed.

Penetrating Offending Vessel, The Most Surgically Demanding Type during Microvascular Decompression Surgery in Hemifacial Spasm

Abstract INTRODUCTION Microvascular decompression (MVD) is the most effective and curative treatment option for neurovascular compression syndrome and it is increasingly performed around the world. This study aimed to identify and describe the most technically difficult cases, which were the patients with penetrating offending vessel through the facial nerve, from our experiences and to give surgical tips for the successful MVD. METHODS Surgical records and intraoperative video of hemifacial spasm patients with penetrating offending vessels were reviewed. Interposition of Teflon felt between nerve and vessel was pursued, and neurectomy was avoided as much as possible. RESULTS Five patients with hemifacial spasm were identified as having a penetrating offending vessel through the facial nerve during the last 5 yr of MVD surgery in our institution. Four AICAs and one PICA were the causative vessels. Partial neurectomy was required in 1 patient. During the median follow-up of 6 mo (range, 1-26), all patients were spasm-free. No patients including the one with partial neurectomy were involved in facial palsy or hearing loss. CONCLUSION MVD in HFS patients with penetrating offending vessel through the facial nerve is the most surgically challenging and demands a high surgical skill. Interposition with Teflon felt is effective and neurectomy should be avoided. Intraoperative monitoring of free-running EMG and abnormal muscle response are helpful to decide the extent of surgery.

Surgical effect and electrophysiological study of patients with hemifacial spasm treated with botulinum toxin or acupuncture before microvascular decompression

ObjectiveWe investigated patients with hemifacial spasm (HFS) who received a botulinum toxin (BT) injection or acupuncture before receiving microvascular decompression (MVD) to determine whether it affects the success rate of surgery. Abnormal Muscle Response (AMR) and Compound Motor Action Potential (CMAP) are commonly used as electrophysiological monitoring methods in surgery, and we will compare the differences between these patients in this regard. Patients and methodsA total of 539 patients with HFS underwent MVD treatment in our department between January 2014 and June 2017. Among them, 83 patients had received BT injection before surgery and were recorded as BT group. Eighty-three patients underwent acupuncture before surgery and were recorded as acupuncture group. Five patients received both BT injection and acupuncture before surgery and were recorded as mixed group. A total of 368 patients who had not received any treatment before surgery were recorded as simple MVD group. We calculated the immediate and long-term remission rates after surgery. AMR and CMAP monitoring were routinely performed during surgery. ResultsImmediate remission rate after surgery was 96.4% (80/83) in BT group, 100% (83/83) in acupuncture group, 100% (5/5) in mixed group, and 95.1% (350/368) in simple MVD group, and the immediate remission rate of BT group is significantly higher than that of simple MVD group (p = 0.04). Long-term remission rate: the remission rates of the four groups were 94.0% (78/83), 97.6% (81/83), 100.0% (5/5) and 92.7%(341/368), respectively, and there is no statistical difference between them (p > 0.05). The amplitude of one branch or several branches of CMAP on the affected side was lower than the healthy side in BT or acupuncture treatment patients. ConclusionsA preoperative BT injection or acupuncture treatment do not reduce the postoperative remission rate of HFS patients treated with MVD, and the amplitude of CMAP on the affected side was lower than the healthy side.

Hemifacial Spasm Caused by Veins Confirmed by Intraoperative Monitoring of Abnormal Muscle Response

BackgroundHemifacial spasm (HFS) is a benign disease caused by the hyper excitement of facial nerves owing to vessel compression. The offending vessels are usually arteries, such as anterior and posterior inferior cerebellar or vertebral arteries, but there are few reports of vein involvement cases.ObjectiveThe aim of this study was to investigate veins as offending vessels in patients with HFS confirmed by abnormal muscle response (AMR).MethodsWe analyzed 5 patients with HFS caused by veins among 78 patients with HFS over the past 10 years. All patients underwent microvascular decompression (MVD) with AMR monitoring, whereas 3 of them underwent a second MVD. The mean follow-up time was 97 months.ResultsArteries were thoroughly decompressed in 3 patients with a failed first MVD surgery who received a second surgery, during which veins at the root exit point (RExP) were decompressed with the disappearance or a significant decrease in the amplitude of AMR. Two patients showed spasm resolution after the first surgery when veins were decompressed together with the disappearance of AMR. The location of veins was RExP and the cisternal portion. All patients had excellent outcomes within 3 months, and no complications were observed.ConclusionsVeins can be offending vessels in HFS patients. AMR is useful to determine the endpoint in these cases. Once arteries are decompressed thoroughly with residual AMR, surrounding veins at unusual sites, such as the RExP or the cisternal portion, must be checked to prevent persistent HFS. Complete decompression of veins leads to a good clinical outcome.

Retrospective clinical analysis of 320 cases of microvascular decompression for hemifacial spasm.

To investigate effects of microvascular decompression (MVD) surgical treatment on hemifacial spasm.A retrospective analysis of 320 adult patients (95 male cases, 29.7% and 225 female cases, 70.3%) with hemifacial spasm treated by surgery was conducted between February 2007 to June 2016, with an average age of 49.3 years and average disease course of 4.9 years. All the 320 cases of patients received MVD. After surgery, all patients were followed up for an average of 2.3 years. Surgical effects were evaluated based on the patients’ symptoms and signs. As this is just a retrospective study that does not involve any interventions, ethical approval was not necessary according to the rules of the hospital.All patients were followed up, no death occurred. Symptom was completely disappeared in 241 cases (75.3%), 50 cases (15.6%) improved; the total effective rate of surgery was 90.9%. No obvious changes of hemifacial spasm were happened in 29 cases (9.1%). There was no deteriorated case.MVD is one of the preferred treatments of hemifacial spasm, the intraoperative electrophysiological monitoring of abnormal muscle response signals contributes to the determination of responsible vessels and fully understanding of delayed resolution is helpful to the accuracy of surgical evaluation.

Repetitive nerve stimulation: Relative muscles sensitivity in generalized myasthenia gravis

Objectives The diagnosis of myasthenia gravis (MG) is established through the medical history and examination and confirmed by the clinical response to anti-cholinesterase medication, the detection of anti-acetylcholine receptor antibodies (AchR) and especially electrodiagnostic testing using repetitive nerve stimulation (RNS) [3] . However, the sensitivity of RNS depends on the distribution of clinically affected muscles and its severity [2] . We aimed to investigate the decrement of RNS of various muscles in patients with generalized MG in order to test the nerve-muscle sensitivity. Methods We performed a retrospective study of patients with clinical diagnosis of MG, who attended our neurology department [2011–2018] (n:33) and we included those with generalized MG to investigate their neurophysiological outcomes. All patients had a neurological examination. Patients who have not a detailed neurophysiological study including RNS within these 3 spots (facial-nerve, accessory-nerve, upper limbs nerves) were excluded. Results Among the 33 patients with MG, we selected 27 patients (M/F:8/19) who had generalized MG with fluctuating motor weakness and oculo-bulbar involvement. Their age ranged from 14 to 77 years (mean, 47.77 years) and the average age at onset was 44.18 years. Forty-four percent had thymus abnormality and 83.33% had positive antibody testing to AchR. RNS studies showed at least one abnormal muscle response (significant decrement > 10% in low frequencies) in 96.29%. Decrement was most detected in the facial nerve (77.77%). An abnormal trapezius response was observed in 55.55%. However, hand muscles abnormalities tested using the ulnar, medial and radial nerves stimulation were detected respectively in 48.14%, 37.03% and 14.81%. The facial nerve was significantly more sensitive than any other nerve (P Conclusion RNS is a commonly used technique to evaluate patients with MG, through multiple nerve-muscle testing [1] . Therefore, the facial nerve seems to be the most sensitive one.

Involved Small Arteries in Patients Who Underwent Microvascular Decompression for Hemifacial Spasm

Microvascular decompression (MVD) has become widely accepted as first-line therapy for hemifacial spasm. However, not all patients are candidates for the procedure, and some surgeons ignore arterioles that represent the actual underlying cause of the condition. The aim of this study was to address the role of involved arterioles in management of MVD in patients with hemifacial spasm. Data were collected from 765 consecutive patients who underwent MVD from January 2009 to August 2010 in our hospital. Electromyographic abnormal muscle response and Z-L response were used to identify the involved arterioles. All patients were followed for 25-35 months. Compression by the involved arterioles was identified in 20 patients. The most commonly involved arteriole was a branch of the anterior inferior cerebellar artery, followed by the posterior inferior cerebellar artery. During follow-up, effective outcomes were achieved in 93.6% of patients with involved arterioles. There was no MVD-related mortality. The main reason for failed MVD is that the involved offending vessel is not correctly identified. Intraoperative abnormal muscle response and Z-L response are good supplementary measures to identify involved arterioles. In addition, not isolating or coagulating the involved arterioles increases the risk associated with the operation.

F114. Utility of intraoperative electromyography in microvascular decompression for hemifacial spasm: Systematic review and meta-analysis

Microvascular decompression (MVD) is the surgical treatment of choice for hemifacial spasm (HFS). During MVD, monitoring of the pathognomonic abnormal lateral spread muscle response (LSR), an evoked electromyographic response to CN VII stimulation, has been traditionally used to monitor adequacy and success of facial nerve decompression and postoperative relief of HFS. In this study, we aim to assess the utility of LSR monitoring in predicting the surgical outcomes after MVDs at discharge, three-months, and one-year. We searched PubMed, Web of Science, and Embase for relevant publications. We included studies reporting on intraoperative LSR monitoring during MVD for HFS and the spasm-free status after the procedure. We calculated the sensitivity, specificity, diagnostic odd ratio, and conditional probability of HFS persistence after post-operative LSR persistence. Forest plot and a summary ROC curve were used for presentation of sensitivity and specificity. Newcastle-Ottawa Scale (NOS) tool was used to assess the quality of included articles. Publication bias was assessed using funnel plots. From 146 studies, 24 studies with 7821 patients were ultimately included in the meta-analysis. The mean age of patients was 53 years. At discharge, postoperative LSR status predicted the clinical outcome of MVD with a specificity (95% CI) of 0.93 (0.87–0.96) and a sensitivity of 0.45 (0.31–0.59). The specificity at three-months and one-year was 0.90 (0.83–0.94) and 0.90 (0.85–0.93) respectively. The sensitivity was found to be 0.43 (0.32–0.55) at three-months and 0.41 (0.29–0.53) at one-year. In addition, the diagnostic odds ratio was found to be 4.71 (3.88–5.71) at discharge, 3.85 (2.96–5.01) at three-months, and 3.18 (2.49–4.08) at one-year. When LSR persisted after MVD, the probability for HFS symptoms persistence was 40% (95% CI, 0.20–0.61) at discharge, 37% (0.14–0.59) at three-months, and 27% (0.11–0.42) at one-year. Intraoperative EMG monitoring for LSR resolution has high specificity but modest sensitivity in predicting the spasm-free status following MVDs for HFS. Post-operative LSR persistence carries a high risk for HFS persistence, therefore, adequacy of decompression should be investigated before closing in cases where intraoperative LSR fails to disappear.

A new method for monitoring abnormal muscle response in hemifacial spasm: A prospective study

ObjectiveTo examine a new abnormal muscle response (AMR) monitoring method during microvascular decompression (MVD) for hemifacial spasm. Methods486 patients with hemifacial spasm were monitored for an AMR during MVD with a new method involving preoperative mapping and intraoperative centrifugal stimulation of the facial nerve. For the last 62 patients, we performed the AMR monitoring using both, the new and conventional methods simultaneously. ResultsPreoperative facial nerve mapping showed that the maximal AMR was detected most frequently (66.9%) at the “F” location (the direction towards the frontalis muscle). An intraoperative AMR was observed in 86.2% of the patients, which disappeared after MVD in 96.4% of the patients. A comparison of the new and conventional methods respectively showed that AMR disappearance after MVD was observed in 98.2% and 61.8% of the patients, no AMR in 0% and 9.1%, and persistent AMR after MVD in 1.8% and 29.1%. ConclusionsThe new AMR monitoring method demonstrated greater AMR monitoring efficacy and supports the finding that disappearance of an AMR is a good indicator of effective decompression during MVD surgery. SignificancePreoperative mapping and intraoperative centrifugal stimulation of the facial nerve during MVD surgery in HFS patients showed greater efficacy of AMR monitoring.

Intraoperative monitoring of Z-L response (ZLR) and abnormal muscle response (AMR) during microvascular decompression for hemifacial spasm. Interpreting the role of ZLR.

Z-L response (ZLR) has been suggested to a new electromyographic (EMG) potential recorded from the facial muscle of patient with hemifacial spasm (HFS) during microvascular decompression (MVD). Although ZLR has been suggested to be useful, experience of ZLR monitoring is limited and its significance during MVD is still unclear. To investigate the significance of ZLR, both ZLR and abnormal muscle response (AMR) were simultaneously recorded before and after decompression of root exit zone (REZ) in 20 consecutive patients with HFS. All 19 AMRs elicited before REZ decompression disappeared immediately after decompression of REZ. ZLRs were also observed before decompression of REZ in 19 (95%) of 20 patients. Despite negative conversion of AMR after decompression in 19 patients, ZLR disappeared in only 13 (68.4%) of 19 patients. Among six sustained ZLRs, three showed reduction in the intensity of ZLRs while the other three remained unchanged. There were nine cases featuring attachment of the distal, non-offending portion of offending vessels to the distal course of the facial nerve in addition to attachment to REZ. Negative ZLR conversion and presence of peripheral contact of offending vessels to distal facial nerves showed significant correlations (p < 0.05). ZLR could be elicited by electrical stimulation at non-REZ-offending portion of the offending arterial wall, attached to the distal course of the facial nerve. HFS disappeared immediately in all 20 patients. Although ZLR might be helpful in cases with multiple offenders, interpretation of ZLR needs caution for non-specific transmission of electric current through vessel wall to facial nerve.

A multivariate analysis for delayed healing of facial muscle spasm after microvascular decompression.

Objectives:To analyze the related factors for delayed healing of facial muscle spasm after microvascular decompression.Methods:After microvascular decompression, 116 of 425 patients with delayed healing were followed up, and their clinical data were analyzed.Results:The incidence rate of postoperative delayed healing was 27.3%, which was not correlated with gender, age or intraoperative vascular compression. However, it was correlated with disease course, severity of preoperative symptoms, arteriosclerosis and abnormal facial muscle response. The duration of delayed healing was positively correlated with preoperative disease course.Conclusions:Delayed healing is a common phenomenon after microvascular decompression for facial muscle spasm, with an elusive reason. Therefore, the treatment outcomes should be evaluated after one year of follow-up.

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.

O3-6-21. Time-dependent changes in intraoperative monitoring findings during microvascular decompression for hemifacial spasm

We analyzed time-dependent changes in the intraoperative monitoring of abnormal muscle responses (AMRs) and facial motor evoked potentials (FMEPs) elicited by transcranial electrical stimulation during microvascular decompression (MVD) in 26 patients with hemifacial spasm. In the orbicularis oculi muscle, the AMRs disappeared in 11 patients before MVD, in six after MVD, and in three during dural closure. The AMRs persisted in six patients. FMEP amplitudes decreased to less than 50% in two patients before MVD, in four after MVD, and in six during dural closure. FMEP amplitudes did not decrease in 14 patients ( p p

O179 Intraoperative blink reflex in microvascular decompression for hemifacial spasm. A case report and proposal of a new method to monitor the efficiency of decompression

Objectives To report the utility of blink reflex (BR) monitoring in microvascular decompression (MVD) for hemifacial spasm (HFS). Methods We report a case of a 64-year-old patient with HFS who underwent MVD with continuous intraoperative neurophysiological monitoring (IONM) of motor, sensory and auditory evoked potentials. The abnormal muscle response (AMR) was monitored with stimulation of zygomatic and buccal branch (zAMR, bAMR) and recording from representative muscles innervated by all facial nerve (FN) branches. Additionally the BR was utilized to monitor the FN functionality. Results Before incision, a similar to AMR-spread phenomenon (BR-spread) was observed when the supraorbital branch of trigeminal nerve was stimulated to elicit BR. Both AMRs (zAMR, bAMR) disappeared during MVD, indicating sufficient FN decompression. Concurrently a similar disappearance from BR-spread and FN-MEPs was observed. During closing all responses (AMRs, BR-spread, FN-MEPs) reappeared. The HFS was clinically present right after the surgery but the patient was relieved from the symptoms a few hours later. Discussion The BR-spread and FN-MEPs showed an AMR-like pattern during MVD. The reappearance of AMRs predicted the immediate but not the long term outcome of HFS-MVD. The BR and FN-MEPs are not reliable to monitor the FN integrity in HFS-MVD due to decompression depended responses. We propose further research to investigate the benefits of BR in HFS-MVD. Conclusions The BR-spread is potentially an alternative IONM tool to determine whether the MVD of HFS is sufficient. Significance A new IONM method is proposed to monitor HFS-MVD.

Clinical study of early disappearance of abnormal muscle response during microvascular decompression for hemifacial spasm

Objective To explore the influencing factors of early disappearance of abnormal muscle response (AMR) during microvascular decompression for hemifacial spasm(HFS) and the clinical outcomes. Methods During the period from January to December of 2014, a total of 372 patients of HFS underwent microvascular decompression (MVD) at Neurosurgery Department of Nanjing Drum Tower Hospital. Characteristic AMR of HFS was observed in 359 patients intraoperatively, among whom 33 patients showed early permanent disappearance of AMR before decompression and the remaining 326 patients did not. Clinical features and outcomes of 359 cases were analyzed retrospectively. Results Offending vessels were identified in all 359 cases. In the 33 patients with early disappearance of AMR, no indentation was observed on their facial nerves, and immediate and delayed (7 days post operation) resolution of symptoms occurred in 32 cases and 1 case, respectively. No complications were reported during the follow-up period in the 33 patients. In the 326 patients without early disappearance of AMR, 39 (12%) cases demonstrated indentation on the facial nerve.In this group, AMR disappeared completely in 305(93.6%) patients after decompression. Although sufficient decompression was achieved, AMR did not disappear in the other 21 (6.4%) patients. Out of the 326 patients, immediate and delayed (2-310 days post operation) symptom resolution occurred in 267 and 57 cases, respectively, and HFS was not relieved in the remaining 2 cases. Hearing loss and delayed facial paralysis were observed in 4 and 9 cases, respectively.The two groups of patients were followed-up for 20-32 months, and no recurrence was observed. The surgical outcomes in patients with early AMR disappearance were significantly better than the other group(P=0.027). The two groups did not differ for postoperative complications. There were no statistically significant differences in gender, age, duration of illness, the side of HFS or the type of offending vessels between the two groups(P>0.05). Conclusions Less stress of offending vessels might be responsible for early disappearance of AMR. Compared with those without early AMR disappearance, the patients whose AMR disappear before decompression seem to have better outcomes. Key words: Hemifacial spasm; Microvascular decompression; Prognosis; Abnormal muscle response; Influencing factors

Electromyographically Guided Nerve Combing Makes Microvascular Decompression More Successful in Hemifacial Spasm with Persistent Abnormal Muscle Response.

Microvascular decompression (MVD) of the facial nerve monitored intraoperatively by abnormal muscle response (AMR) activity is a common treatment for hemifacial spasm. AMR frequently persists after MVD, however, for which electromyography (EMG)-guided nerve combing sometimes is recommended. Because no research regarding the success of EMG-guided nerve combing has been published, we compared the effectiveness of nerve combing after MVD with simple MVD in cases including persistent AMR. A retrospective study of 127 cases of hemifacial spasm treated with persistent AMR after MVD treatment occurring between January 2011 and June 2015 was conducted. Among the 127 total cases, EMG-guided nerve combing was used in 72 patients and simple MVD in 55 patients. For simple MVD, success rates at 1 day, 7 days, 1 month, 3 months, and 1 year after surgery were all approximately 80%; the success rates of MVD with nerve combing were significantly greater (P < 0.05) than those of simple MVD, by 15.83%, 15.4%, 17.22%, 17.65%, and 17.65%, respectively. The incidence rates of facial palsy in simple MVD were 12.73%, 14.55%, 10.91%, 3.64%, and 1.82%, respectively; those in the nerve combing group were 27.78% (P < 0.05 vs. simple MVD), 33.33% (P < 0.05), 25.00% (P=0.05), 5.55% (P > 0.05), and 2.78% (P > 0.05), respectively. In cases of hemifacial spasm with persistent AMR after MVD, EMG-guided nerve combing significantly improved the success rate of the operation. Although it also significantly increased the incidence of postoperative facial palsy over the short term (up to 1 week), incidences in the long term were not significantly different.

The Effects of Dual Abnormal Muscle Response Monitoring on Microvascular Decompression in Patients with Hemifacial Spasm.

Microvascular decompression (MVD) is the most useful treatment for hemifacial spasm (HFS). During MVD surgery, traditional abnormal muscle response (tAMR) is widely used to monitor success in decompressing the facial nerve. Dual AMR (dAMR) is a new monitoring method used during MVD for HFS. We compared the sensitivities and reliabilities of tAMR and dAMR. We performed a retrospective study of 1301 cases of HFS treated using MVD between January 2014 and March 2016. Among the 1301 cases, 587 patients underwent tAMR monitoring and 714 underwent dAMR monitoring. Typical abnormal muscle response (AMR) waveforms were observed in 484 patients (82.5%) in the tAMR group and in 688 patients (96.4%) in the dAMR group (P < 0.05). AMR waveforms disappeared in 459 patients in the tAMR group and in 655 patients in the dAMR group during MVD. One day, 7 days, 1 month, and 3 months after MVD surgeries with AMR disappearance, the effective rate of MVD was 95.0%, 94.3%, 94.5%, and 95.0%, respectively, in the tAMR group. The corresponding rates were 97.7%, 96.9%, 97.3%, and 98.0% in the dAMR group (P < 0.05). One day, 7 days, 1 month, and 3 months after MVD surgeries with AMR persistence, the effective rate of MVD was 68.0%, 64.0%, 64.0%, and 64.0%, respectively, in the tAMR group. The corresponding rates were 90.9%, 87.9%, 87.9%, and 90.9% in the dAMR group (P < 0.05). AMR monitoring provides valuable neurosurgical guidance during MVD for HFS. dAMR monitoring has better sensitivity and reliability than tAMR monitoring.

The Significance of Abnormal Muscle Response Monitoring During Microvascular Decompression for Hemifacial Spasm.

Despite the wide adoption of the abnormal muscle response (AMR) to electrical stimulation of the facial nerve during microvascular decompression (MVD) surgery, the value of AMR in the prognosis of the postoperative outcome is still controversial. In order to better use this intraoperative electrophysiology, it is necessary to further address the relationship between AMR and postoperative results. Three hundred and thirty-two patients with hemifacial spasm (HFS) in whom MVD surgery was performed and in whom AMR was available were finally enrolled in this study. The intraoperative AMR changes were classified as amplitude ≥ 50 %, <50 %, and disappearance. These changes were retrospectively analyzed in association with intraoperative findings and postoperative outcomes. The follow-up period ranged from 11 to 62 months, with an average of 34.1 months. Among the 332 patients with a typical AMR wave recorded at the beginning of the operation, the AMR disappeared in 305, and amplitude was <50 % in 11 and ≥50 % in 16. Of those with AMR disappearance plus those with amplitude < 50 %, 98.4 % achieved relief on the first postoperative day and at the latest follow-up, while of those with amplitude ≥50 %, 18.8 % and 25 %, respectively, achieved relief on the first postoperative day and at the latest follow-up (P < 0.01). Accordingly, a more than 50 % decrease of AMR amplitude may predict a good prognosis. The accuracy, sensitivity, and specificity of AMR monitoring were 97.5 %, 99 %, and 72.2 %, respectively. AMR could be a good tool for successful MVD in patients with HFS when a rational analysis is conducted in association with the intraoperative findings. Persistence of AMR may imply that the real offending vessel was missed. If the entire facial nerve root is cleared of any vessel, a remaining AMR amplitude of less than 50 % might be acceptable. Otherwise, neurocombing is suggested before finishing the operation.