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Objective: To discuss effect of intraoperative compound abnormal muscle response (AMR) in patients undergoing microvascular decompression (MVD) for hemifacial spasm (HFS)., Methods: Eighty-six HFS patients were underwent single or compound AMR monitoring during MVD. Single AMR recording was from the frontal muscle by stimulation of the marginal mandibular branch. Compound AMR recordings were obtained from the orbicularis oris and mentalis muscles by electrical stimulation of the temporal branch of the facial nerve, and from the frontal and orbicularis oculi muscles by stimulation of the marginal mandibular branch. Clinical outcome was compared with compound AMR results at the completion of MVD., Results: Forty-two of 45 patients' AMR were recorded by compound AMR monitoring and 34 of 41 patients' AMR were recorded by single AMR monitoring during MVD. Hemifacial spasm resolved completely in 41 patients whose compound AMR was recorded and in 26 patients whose single AMR was recorded. Compound AMR gained a sensitivity of 96.3% and a specificity of 97.2%. Correspondingly, single AMR gained a sensitivity of 97.1% and a specificity of 86.3%., Conclusions: Our results suggest that compound AMR is more suitable than single AMR in MVD for HFS., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by Mutaz B. Habal, MD.)

Objective:  The aim of the present study was to evaluate the efficacy and safety of microvascular decompression (MVD) for primary hemifacial spasm (HFS) in patients aged ≥70 years and to compare the outcome with a control cohort of younger patients(<70 years)., Methods:  In this retrospective study, subjects were divided into two groups: an elderly group (patients who were ≥70 years) and a younger group. We compared demographic and clinical data, surgical outcome, MVD-related complications, and duration of operation and hospitalization after MVD between the two groups., Results:  At a mean follow-up of 32 ± 4.2 months, 188 elderly patients (90.4%) reported an effective outcome without need for any medication versus 379 (91.1%) of the younger cohort. There was no mortality in both cohorts. The prevalence of delayed facial palsy was 4.8% in the elderly group and 4.1% in the younger group. One (0.5%) patient in the elderly group and 3 (0.7%) patients in the younger group suffered cerebrospinal fluid (CSF) leakage. There was no significant difference between the two groups in terms of MVD-related complications, such as delayed facial palsy, hearing impairment, CSF leakage, and hematoma., Conclusions:  MVD is an effective treatment option in elderly patients with HFS as well as in younger patients. Age itself seems to be no relevant contraindication or, alternatively, risk factor regarding MVD., Competing Interests: None declared., (Thieme. All rights reserved.)

Objective: Hemifacial spasm (HFS) is usually caused by compression of the facial nerve at the root exit zone (REZ), and is extremely rare in adolescents and even rarer in aneurysm compression., Case Report: We describe symptomatic hemifacial spasm caused by a saccular aneurysm of the anterior inferior cerebellar artery (AICA) that was treated by clipping. A 17-year-old adolescent developed left hemifacial spasm that had gradually worsened over a period of 1 year before admission to our department. During the course of MVD (microvascular decompression), saccular aneurysm of AICA was accidentally found to compress the facial nerve. The cause of the facial spasm was considered to be compression of the left facial nerve by the aneurysm. Clipping the aneurysm was performed. The hemifacial spasm disappeared immediately., Conclusion: Our report indicates that HFS caused by saccular aneurysm of AICA can be treated by clipping, and that aneurysms should be considered in the treatment of adolescent HFS, especially those difficult to identify on imaging examination.

Objective:  To evaluate clinical features, outcomes, and complications in patients with hemifacial spasm (HFS) after microvascular decompression (MVD) of different offending vessels., Methods:  Clinical data were collected from 362 patients with HFS treated with MVD between January 2013 and January 2014. Patients were divided into five groups based on the offending vessel: A (anterior inferior cerebellar artery [AICA] compression), B (posterior inferior cerebellar artery [PICA] compression), C (AICA plus PICA compression), D (vertebral artery [VA] compression), and E (VA plus small vessel compression)., Results:  The most common offending vessel was the AICA (51.38%). The most common compression site was the root exit zone. During the follow-up period, the effective rate was 95.48% in group A, 92.15% in group B, 93.10% in group C, 90.14% in group D, and 91.45% in group E. Twenty-nine patients exhibited delayed facial palsy, the most common complication., Conclusion:  No statistically significant differences were found in long-term outcomes or MVD-related complications among the study groups. The type of offending vessel was not a prognostic factor for MVD in patients with HFS., Competing Interests: None declared., (Georg Thieme Verlag KG Stuttgart · New York.)

Background: Hemifacial spasm (HFS) is generally caused by the root exit zone of the facial nerve compressed by an overlying arterial loop. HFS can also be caused by various types of tumor, aneurysm, or arteriovenous malformation. We retrospectively analyzed patients to evaluate possible differences in the demographic and clinical features between primary and secondary HFS., Methods: A retrospective study of 3140 cases of HFS treated in our department between January 2009 and June 2016. Among the 3140 total cases, 26 patients had secondary HFS., Results: The 26 tumors of secondary HFS included 11 meningiomas, 8 epidermoid cysts, and 7 vestibular schwannomas. Compared to those with idiopathic HFS, those patients with tumor-induced HFS were significantly younger (P < 0.05). Secondary HFS tended to have responsible vessels, and were observed in 20 (76.92%) of these 26 patients. The long-term effective rate of operation was 84% in the secondary HFS group and was 96.45% in the primary HFS group (P < 0.05); the incidence rate of complication was 12% in the secondary HFS group and was 3.06% in the primary HFS group (P < 0.05)., Conclusions: In cases of secondary HFS, facial nerves of most patients were compressed by blood vessels, so microvascular decompression after tumor resection plays an important role. We should examine the entire nerve root for possible vascular compression., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: 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., Methods: 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., Results: 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., Conclusions: 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., (Copyright © 2018. Published by Elsevier Inc.)

Background: Microvascular decompression (MVD) is useful treatment for hemifacial spasm (HFS) with refractory hypertension (RHTN). The biomedical glue sling technique is a new method for MVD. In this study, we retrospectively compared the outcome of the biomedical glue sling technique with traditional technique in MVD for HFS with RHTN., Methods: A retrospective study of HFS with RHTN treated by MVD was conducted between January 2010 and June 2016. Among 155 patients who underwent their first MVD at our institution, traditional technique was performed in 73 cases of patients and the biomedical glue sling technique was performed on 82 patients., Results: At 3 days, 7 days, 1 month, 3 months, and 1 year after MVD surgery, in the traditional technique group the effective rates of MVD for HFS were 86.30%, 84.93%, 87.14%, 84.06%, and 83.33%. The effective rates for RHTN were 68.49%, 67.12%, 65.71%, 57.97%, and 57.58%. The incidence rates of complication were 5.48%, 5.48%, 4.29%, 2.90%, and 3.03%. In the biomedical glue sling technique group, the effective rates of MVD for HFS were 97.56%, 97.56%, 98.75%, 96.15%, and 94.59% (P < 0.05). The effective rates for RHTN were 85.37%, 82.93%, 81.25%, 79.49%, and 75.68% (P < 0.05). The incidence rates of complication were 6.10%, 6.10%, 5.00%, 3.85%, and 2.70% (P > 0.05)., Conclusion: When HFS is associated with RHTN, the efficacy of the biomedical glue sling technique for MVD is higher than that of the traditional technique for both HFS and RHTN., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: Hemifacial spasm (HFS) is a disorder characterized by intermittent, involuntary facial muscle contractions. Microvascular decompression (MVD) is the gold treatment for HFS. The aim of this research was to discuss whether patients undergoing MVD as their initial surgical intervention experience greater spasm control than patients experiencing an MVD performed as a subsequent surgical intervention., Methods: The study included 976 patients with HFS, 452 of whom (group A) underwent MVD as their initial surgical intervention and 524 of whom (group B) underwent subsequent MVD. Relevant clinical data including outcome of MVD, operative findings, complications, and so on were collected immediately after MVD operation and at follow-up., Results: The follow-up period was 7-9 years (mean, 7.96 ± 0.87 years). The mean age at intervention was 53.14 years and 55.43 years in the 2 groups, respectively. The long-term postoperative relief rate of patients in the 2 groups was 98.23% and 87.21%, respectively. There was a significant difference in long-term postoperative relief rate of patients between the 2 groups (P < 0.05)., Conclusions: Patients undergoing MVD for HFS as the primary treatment experience better long-term efficacy than patients first treated with botulinum neurotoxin type A., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: 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., Methods: 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., Results: 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)., Conclusions: 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., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Although microvascular decompression (MVD) surgery is considered the gold standard treatment for hemifacial spasm, there are some MVD-related complications., Methods: We retrospectively reviewed 1548 patients with hemifacial spasm who underwent retromastoid suboccipital craniectomy with MVD from January 2009 to June 2013. All patients were followed for >2 years., Results: Excellent and good results were 92.5% and 4.2%, respectively. Postoperative complications were recorded in 16.09% (n = 249). There was no MVD-related mortality. After MVD surgery, the most frequent complications were occipital sensory disturbance (7.3%), facial nerve palsy (9.7%), and hearing impairment (3.5%). Other complications were as follows: cerebrospinal fluid leakage (n = 24), poor healing wound (n = 14), lower cranial nerve palsy (n = 12), wound infection (n = 4), and hemorrhage (n = 2)., Conclusions: MVD operation is a safe treatment for hemifacial spasm. Facial nerve palsy is the most common MVD-related complication; preservation of the lesser occipital nerve during MVD surgery can decrease the rate of occipital sensory disturbance. Permanent or serious complications are comparatively rare in MVD surgery., (Copyright © 2017. Published by Elsevier Inc.)

Background: Few studies have examined atypical hemifacial spasm (AHFS), and the mechanism of AHFS remains unclear. In this study, we examined the etiology, prognosis, and treatment of AHFS., Methods: We retrospectively analyzed the clinical data for 14 consecutive patients that underwent microvascular decompression (MVD) for AHFS between January 2014 and December 2015. Clinical features, outcomes, and complications were evaluated., Results: The incidence of AHFS is 1.52%. There were no significant differences in sex, age, side and duration between the typical hemifacial spasm and AHFS. During the follow-up period, the effective rate of MVD for patients with AHFS was 92.3%. Three patients developed delayed facial nerve palsy postoperatively, 1 patient experienced occipital sensory disturbance, and 1 patient suffered hearing loss., Conclusions: Most of the cases of AHFS studied here were caused by neurovascular conflict in zone IV of the facial nerve distal to the root entry zone. MVD surgery is the first choice treatment for AHFS., (Copyright © 2017. Published by Elsevier Inc.)

Objective: To make out the way to distinguish the offending vessels compressed the internal auditory canal part of the facial nerve., Methods: The hemifacial spasm patients were treated of microvascular decompression surgery with neurophysiologic monitoring. The patients were found that the internal auditory canal of the facial nerves was fully compressed, and the records of surgery monitoring were analyzed., Results: All the patients were recorded the delay incubation period in electromyography monitoring, and all patients were hemifacial spasm free finally., Conclusion: Some hemifacial spasms were caused by internal auditory canal compression, so during the operation, the authors should explore the whole course of the facial nerve and compress the internal auditory canal part with the aid of neurophysiologic monitoring.

Background: Microvascular decompression (MVD) is the most useful treatment for hemifacial spasm (HFS). In patients of vertebral artery (VA) compression of the facial nerve, MVD is often difficult. Many of the VA are obviously atherosclerotic. In this study, the authors retrospectively compared the effect of MVD for HFS associated with the atherosclerosis of vertebral artery (aVA) with that of MVD for HFS with normal vertebral artery (nVA)., Methods: A retrospective study of HFS treated by MVD was conducted between January 2014 and October 2015. There were 186 patients with VA-associated HFS who underwent their first MVD at the authors' institution. Among them, 52 patients of HFS were associated with aVA and 134 patients were associated with nVA., Results: At 1 day, 7 days, 1 month, 3 months, and 1 year after MVD surgery, in aVA group, the effective rate of MVD was 80.77%, 80.77%, 82.00%, 79.59%, and 82.61%, the incidence rate of complication was 15.83%, 13.46%, 14.00%, 12.24%, and 10.87%; in nVA group, the effective rate of operation was 94.03%, 94.78%, 95.42%, 94.53%, and 95.12% (P < 0.05), the incidence rate of complication was 4.48%, 4.48%, 3.82%, 3.13%, and 1.63% (P < 0.05)., Conclusion: When the HFS was associated with the aVA, the effective rate of MVD was lower and the incidence of complication was higher than those associated with nVA. In MVD of HFS associated with aVA, the full decompression of the facial nerve and the minimal traction of surrounding tissue in the operation are the key to the success of MVD.

Background: Microvascular decompression (MVD) is the most useful treatment for hemifacial spasm (HFS). In cases of vertebral artery (VA) compression of the facial nerve, MVD is often difficult. In this study, we compared the outcome of the biomedical glue sling technique with the traditional technique in MVD for HFS involving the VA., Methods: A retrospective study of patients with HFS treated by MVD was conducted between January 2013 and December 2015. A total of 327 patients with VA-associated HFS underwent their first MVD at our institution. Among them, the traditional technique was performed in 153 patients and the biomedical glue sling technique was performed in 174 patients. We measured effectiveness at 1 day, 7 days, 1 month, 3 months, and 1 year after MVD surgery., Results: In the traditional technique group, the effective rates of MVD were 89.54%, 88.89%, 89.40%, 88.44%, and 86.71%, and the incidence rates of complication were 5.23%, 4.58%, 3.97%, 2.72%, and 0.70%. In the biomedical glue sling technique group, the effective rates of operation were 96.55%, 96.55%, 97.66%, 95.86%, and 95.76% (P < 0.05), and the incidence rates of complication were 8.62%, 8.62%, 7.60%, 4.73%, and 2.42% (P > 0.05)., Conclusion: When the HFS were associated with the VA, the effective rate of biomedical glue sling technique of MVD was higher than the traditional technique, and there was no statistical difference between the 2 groups about the incidence of complication., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: 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., Methods: 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., Results: 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., Conclusions: 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., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: 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., Methods: 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., Results: 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)., Conclusions: AMR monitoring provides valuable neurosurgical guidance during MVD for HFS. dAMR monitoring has better sensitivity and reliability than tAMR monitoring., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Microvascular decompression (MVD) has become the best treatment for hemifacial spasm (HFS); however, some patients do not obtain complete relief after the initial MVD. We analyzed a group of patients who underwent a second MVD, to identify the factors that prevented relief after the initial MVD and those that promote the success of the second procedure., Methods: Of a group of 1400 patients with typical primary unilateral HFS treated with MVD between January 2014 and October 2015, we focused on 42 patients with poor postoperative outcomes. All patients underwent abnormal muscle response (AMR) monitoring again the day after surgery. Of those patients, 35 underwent a second MVD surgery within a week. We analyzed their AMRs after each operation., Results: After the first operation, AMR was positive in 40 patients and negative in 2 patients. The latter 2 patients reported spontaneous relief within 1 week. Among the 40 positive patients, 35 and 4 patients underwent a second MVD within a week and 6-11 months, respectively. Thirty-nine patients reported relief after the second MVD; 1 patient remained unchanged at follow-up (<12 months)., Conclusions: When initial MVD does not provide relief, a repeat MVD should be performed as soon as possible. In 2/42 cases, relief was delayed enough that AMR had a false-negative result. Combinative monitoring of AMR and Z-L responses was important in identifying the real cause of HFS., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Microvascular decompression (MVD) has been accepted worldwide as a reasonable treatment for hemifacial spasm (HFS); however, resolution of the HFS is often gradual. To conclude the delayed relief rate of the MVD for the treatment of HFS, we conducted a systematic review. Using the keywords delayed relief, hemifacial spasm, or microvascular decompression, articles published in English-language journals and indexed in PubMed between June 1, 1994 and June 1, 2014 on the treatment of HFS with emphasis on delayed relief were considered for this study. Twelve articles with 2727 patients with HFS were finally enrolled in this review. Among all the patients, the ratio of male versus female was 1:2.7, and left versus right was 1:1.6. The average age at surgery was 52.5 years (49.1-55.9 y), with HFS symptom duration of 68.4 months (38.4-98.4 mo) before the surgery. The average follow-up duration was 49 months (6.4-121.6 mo). After examining all the patients, we obtained a mean postoperative success rate of 85.1% (76.5%-93.5%), but the success rate after the MVD immediately is only 71.8% (59.5%-84%). The mean rate of delayed relief was 25.4% (18.8%-37.1%). Approximately 13.1% (5.9%-19.7%) of the patients with symptom recurrence resorted to repeated MVD during the follow-up period. Accordingly, MVD is the most effective treatment for patients with HFS, but some of the patients may experienced delayed relief, which could be avoided if a thorough decompression of the facial nerve root had been obtained.

Although neurovascular confliction was believed to be the cause of hemifacial spasm (HFS), the mechanism of the disorder remains unclear to date. Current theories, merely focusing on the facial nerve, have failed to explain the clinical phenomenon of immediate relief following a successful microvascular decompression surgery (MVD). With the experience of thousands of microvascular decompression surgeries and preliminary investigations, we have learned that the offending artery may play a more important role than the effect of merely mechanical compression in the pathogenesis of the disease. We believe that the attrition of neurovascular interface is the essence of the etiology, and the substance of the disease is emersion of ectopic action potentials from the demyelinated facial nerve fibers, which were triggered by the sympathetic endings from the offending artery wall. In this paper, we put forward evidence to support this hypothesis, both logically and theoretically.

Background: Although microvascular decompression (MVD) surgery has been widely accepted as an effective treatment for hemifacial spasm (HFS), delayed relief cases have been frequently reported. Therefore, the value of an immediate redo MVD should be discussed., Methods: This study included 1,435 HFS patients who underwent MVD with intraoperative abnormal muscle response (AMR) monitoring from 2011 through 2013 at XinHua Hospital. These cases were analyzed retrospectively with emphasis on the postoperative outcomes and introaperative findings., Results: After MVD, 1,384 HFS patients obtained relief immediately. The 51 unrelieved patients underwent AMR monitoring again the next day; this was positive in 48 and negative in 3 patients. These three patients with negative AMR obtained relief spontaneously within a week. Among the 48 positive patients, 31 and 11 were underwent redo MVD within a week and 5-22 months, respectively, and all achieved relief after the second operation. Of the six remainig patients, two obtained relief within 2 months and 4 remained unchanged in the up-to-3-year's follow-up period. In redo MVDs, insufficient decompression of the facial nerve accounted for the failure. Finally, in this database, the immediate postoperative cure rate was 96.4 %; with earlier redo MVD, the final cure rate could be increased to 99.9 %., Conclusions: Despite being a reasonable remedy for HFS in the hands of an experienced neurosurgeon, sometimes small vessels can be missed while managing the main offending arteries during MVDs, which might account for the delayed relief. Therefore, reexamination of the AMR is necessary for unimproved patients; if a positive result is recorded, an immediate redo MVD is suggested.

Our previous studies demonstrated that the abnormal muscle response could vanish when the ipsilateral superior cervical ganglion was removed and reappear when norepinephrine was dripped at the neurovascular conflict site. Evidentially, we believed that the mechanism of hemifacial spasm should involve emersion of ectopical action potential in the compressed facial nerve fibers. As the action potential is ignited by ion channel opening, we focused on Nav1.8 that has been found overexpressed in peripheral nerve while damaged. In this study, Moller model was adopted, 20 Sprague-Dawley rats underwent drip of norepinephrine, and the abnormal muscle response wave was monitored in 14 rats. Antibodies against unique epitopes of the α subunit of sodium channel isoforms were used to detect the Nav1.8 neuronal isoforms, and the immunohistochemistry showed strong staining in 13 rats, which were all in the abnormal muscle response positive group (P < 0.05). Accordingly, we concluded that the substance of hemifacial spasm is an ectopic action potential that emerged on the damaged facial nerve, which might be coupled by Nav1.8.

Background: Multiple neurovascular compression is present in about 38 % cases of hemifacial spasm (HFS). In these cases, the vertebral artery (VA) compresses another vessel, which in turn compresses the nerve. This type was named as "the tandem type". In the tandem type, the real offending vessel is often concealed by the VA. It is sometimes neglected by the surgeons. In this study, we report our experience in using abnormal muscle response (AMR) and ZL-Response (ZLR) simultaneously as intraoperative monitoring for MVD surgery of HFS with "the tandem type" vascular compression involving VA., Methods: Fourteen "tandem type" patients treated with microvascular decompression surgery (MVD) surgery were included. ZLR and AMR were recorded simultaneously to identify the offending vessels in operation., Results: After MVD surgery, 13 patients achieved excellent resolution of spasm. In one case, the patient failed to attain resolution in the first operation, underwent early reoperation and had good resolution. There were no operative deaths or serious operative complications. In all 14 cases, we found that VA compressed the anterior inferior cerebellar artery (AICA) or posterior inferior cerebellar artery (PICA), which in turn compressed the root exit zone (REZ). A typical ZLR was identified from the AICA or PICA but not from the VA. AMR was absent in one case and persisted in one case. After the VA was transposed, the typical AMR was unchanged, unstable or disappeared, and ZLR from the AICA/PICA also existed. AMR and ZLR did not disappear until AICA/PICA was sufficiently decompressed., Conclusions: The combination of AMR and ZLR provides more useful information than does the AMR alone, and ZLR may be the only useful intraoperative monitoring for MVD surgery in times when AMR is absent or persists. ZLR played a crucial role in finding the real offending vessel, which was often concealed by the VA in tandem type.

Background: Trigeminal neuralgia(TN), hemifacial spasm (HFS) and glossopharyngeal neuralgia (GPN) were referred to hyperactive dysfunction syndromes (HDSs) of the cranial nerves. These symptoms may occur synchronously or metachronously, but the combination of three diseases is extremely rare., Methods: From 2007 through 2013, six patients with coexistent GPN-HFS-TN were treated in our department. The combined symptoms occurred on the same side in three and on both sides in three. These patients underwent nine microvascular decompression (MVD) procedures in total. The clinical data including operative findings were respectively analyzed, and the etiological factors as well as treatment strategies were discussed., Results: Intraoperatively, in all the cases a small posterior fossa was found, which was crowded with cranial nerve roots and cerbellar vesels. Postoperatively, spasm was stopped immediately in four and within 3 months in two; the symptom of TN disappeared immediately in four and within 2 weeks in two; the symptom of GPN was relieved immediately in four and improved with medication in two. During the up to 77 months' follow-up, no changes, recurrence or any dysfunctions of cranial nerves were observed in any of the patients., Conclusions: The combination of HFS-TN-GPN is extremely rare and is often associated with a looped VBA and a smaller posterior fossa. However, MVD is still a good choice for treatment. To achieve a safe and effective outcome, dissection of the caudal cranial nerves and proximal transposition of the vertebral artery before decompression of the affected nerve roots are strongly recommended.

Hemimasticatory spasm is a rare disease; with little knowledge of the pathogenesis, it has still been intractable today. We presented a 56-year-old woman with involuntary painful spasm in her left masseter muscle for 11 years. The patient was successfully treated with microvascular decompression surgery. An offending superior cerebellar artery was found to contact with the motor branch of the trigeminal nerve root, which was then removed away and pieces of soft wadding were interposed between the nerve and the vessel to assure the separation. Postoperatively, the symptom totally disappeared and no recurrence was observed during the 7 months' follow-up. The treatment as well as the pathogenesis of the disease was reviewed, and we put forward a new hypothesis.

Painful tic convulsif is referred to as the concurrent trigeminal neuralgia and hemifacial spasm. However, painful tic convulsif after ipsilateral Bell palsy has never been reported before. We report a case of a 77-year-old woman with coexistent trigeminal neuralgia and hemifacial spasm who had experienced Bell palsy half a year ago. The patient underwent microvascular decompression. Intraoperatively, the vertebrobasilar artery was found to deviate to the symptomatic side and a severe adhesion was observed in the cerebellopontine angle. Meanwhile, an ectatic anterior inferior cerebellar artery and 2 branches of the superior cerebellar artery were identified to compress the caudal root entry zone (REZ) of the VII nerve and the rostroventral cisternal portion of the V nerve, respectively. Postoperatively, the symptoms of spasm ceased immediately and the pain disappeared within 3 months. In this article, the pathogenesis of the patient's illness was discussed and it was assumed that the adhesions developed from inflammatory reactions after Bell palsy and the anatomic features of the patient were the factors that generated the disorder. Microvascular decompression surgery is the suggested treatment of the disease, and the dissection should be started from the caudal cranial nerves while performing the operation.

Hemimasticatory spasm is a rare disorder characterized by paroxysmal involuntary contraction of the jaw-closing muscles. As the ideology and pathogenesis of the disease are still unclear, there has been no treatment that could give rise to a good outcome so far. Herein, we tried to use surgical management to cure the disease. Six patients with the disease were included in this study. These patients underwent microvascular decompression of the motor fibers of the trigeminal root. After the operation, all faces of the patients felt relaxed at varied degrees, except for 1 patient. Our study showed that microvascular decompression of the trigeminal nerve could lead to a better outcome. However, a control study with a large sample is needed before this technique is widely used.

Objectives: Despite the vascular compression of the seventh cranial nerve has been verified by the microvascular decompression surgery as the cause of hemifacial spasm (HFS), the mechanism of the disease is still unknown. We believe that the autonomic nervous system in adventitia of the offending artery may contribute to the HFS. To prove our hypothesis, we performed an experiment in SD rats., Methods: Moller's HFS model was adopted and the abnormal muscle response (AMR) wave was electrophysiologically monitored. With randomization, some HFS rats underwent exclusion of the offending artery or removal of the ipsilateral superior cervical ganglion. Some HFS rats with negative AMR following exclusion of the offending artery were dripped with norepinephrine onto the neurovascular conflict site., Results: With exclusion of the offending artery, AMR disappeared in 14 (70%) of the 20 HFS rats, while in three (30%) of the 10 from sham operation group (P<0·05). With ganglionectomy, AMR disappeared in 12 (75%) of the 16 HFS rats, while in two (25%) of the eight from the sham operation group (P<0·05). With norepinephrine drip, AMR reappeared in four (67%) of the six from those offending-artery-excluded HFS rats, while in zero of the six from normal-saline-dripped group (P<0·05)., Discussion: The neurotransmitter releasing from the autonomic nervous endings in the worn adventitia of the offending artery may induce an ectopia action potential in those demyelinated facial nerve fibers expanding to the neuromuscular conjunction and trigger an attack of HFS.

Objective: Although microvascular decompression (MVD) has been accepted as effective therapy for hemifacial spasm, failed surgery has been reported frequently. For a sophisticated neurosurgeon, an apparent offending artery is seldom missed. However, it is still an embarrassed situation when the neurovascular conflict site could not be approached., Methods: Clinical data were collected from consecutive 211 MVDs in 2010. Intraoperative abnormal muscle response was recorded. Among them, the neurovascular conflict was not finally discovered in 3 patients, whom were then focused on. All patients were followed up for 6 to 15 months., Results: In 17 of the 211 MVDs, the cerebellum was hard to be retracted because of adhesions. After careful dissection, a working space was finally created in the cerebellopontine angle. However, there still were 3 cases, whose neurovascular conflict site was unable to be discovered at last because of a branch of an artery embedded in the petrous bone and made the cerebellum unmovable. With navigation of real-time abnormal muscle response, the offending artery was moved away eventually even without exposing the conflict site. Postoperatively, all the patients were completely spasm-free immediately. No recurrence was noticed in the last follow-up period., Conclusions: The most important thing for a successful MVD operation is to remove the offending artery off the nerve. However, if the conflict site failed to be approached after endeavors, a successful MVD can still be achieved by relocating the offending artery with the guidance of real-time electromyography even without visualization of the confliction.

Objective: Despite the microvascular decompression (MVD) has become a definitive treatment for trigeminal neuralgia (TN) and hemifacial spasm (HFS), not all of the patients have been cured completely so far and this sort of operation is still with risk because of the critical operative area. In order to refine this surgery, we investigated thousands MVDs., Methods: Among 3000 consecutive cases of MVDs have been performed in our department, 2601 were those with typical TN or HFS, who were then enrolled in this investigation. They were retrospectively analyzed with emphasis on the correlation between surgical findings and postoperative outcomes. The differences between TN and HFS cases were compared. The strategy of each surgical process of MVD was addressed., Results: Postoperatively, the pain free or spasm cease occurred immediately in 88.3%. The symptoms improved at some degree in 7.2%. The symptoms unimproved at all in 4.5%. Most of those with poor outcome underwent a redo MVD in the following days. Eventually, their symptoms were then improved in 98.7% of the reoperative patients. The majority reason of the failed surgery was that the neurovascular conflict located beyond REZ or the offending veins were missed for TN, while the exact offending artery (arteriole) was missed for HFS as it located far more medially than expected., Conclusion: A prompt recognition of the conflict site leads to a successful MVD. To facilitate the approach, the craniotomy should be lateral enough to the sigmoid sinus. The whole intracranial nerve root should be examined and veins or arterioles should not be ignored. For TN, all the vessels contacting the nerve should be detached. For HFS, the exposure should be medial enough to the pontomedullary sulcus., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Although microvascular decompression (MVD) is accepted as an effective therapy for hemifacial spasm (HFS), some operations fail. While performing MVD, many surgeons focus on the large arteries but ignore the arterioles. Failure to identify involved arterioles may account for unsuccessful MVD. We aimed to refine the MVD surgery and improve post-operative outcomes by proper management of involved arterioles. Clinical data were collected from 69 consecutive patients who underwent MVD. Intraoperative electromyography (EMG) was employed for each MVD. Each operation was reviewed with a focus on the involved arterioles. All patients were followed up for between nine and 12 months. An abnormal muscle response (AMR) wave was identified by EMG in all patients before decompression, but vanished in most patients as soon as the involved arteries were removed from the cranial nerve (CN). However, in nine of 69 patients, the AMR did not immediately disappear. Further dissection and exploration of the entire CN VII identified an arteriole in contact with, or in some patients embedded in, the nerve. Once the arteriole was isolated from the CN, the AMR disappeared. After surgery, spasms ceased in all patients and no recurrence was found up to the one-year follow-up. To achieve a positive post-operative outcome, exploration of the entire CN VII is necessary, with a focus on the small arterioles. AMR can be a good adjuvant to identify the involved arterioles., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

We studied the correlation between the anatomy of the vertebral artery (VA) and the symptoms of primary hemifacial spasm (HFS). Between June and October 2009, 88 patients with primary HFS underwent a preoperative MRI and subsequent microvascular decompression surgery. Each patient's VA was categorized into one of three types according to their MRI findings. In Type I, the bilateral VA that join to form the basilar artery in the mid line appear symmetrical. In Type II, the VA distribute asymmetrically and deviate to one side (Type IIa deviate to the symptomatic side; Type IIb to the contralateral side). In Type III, both VA occur on the same side (Type IIIa occur on the symptomatic side; Type IIIb on the contralateral side). The correlation between deviation of the VA and the symptomatic side of primary HFS was analyzed statistically. Of the 88 patients, the number of patients with each type of VA, as identified by three-dimensional time-of-flight MRI was: Type I=3, Type II=48 (Type IIa=40, Type IIb=8) and Type III=37 (Type IIIa=36, Type IIIb=1). The anatomical characteristics of the VA (lateral deviation) were significantly related to the symptomatic side of the primary HFS (chi-squared [χ(2)]=102.14; p<0.01; relative risk=8.44). The likelihood that the VA deviated to the symptomatic side was 86.4%, while the likelihood of deviation to the asymptomatic side was 10.2%. Thus, anatomical variation of the VA (lateral deviation) is one of the risk factors for primary HFS., (Copyright © 2011. Published by Elsevier Ltd.)

Background: Although microvascular decompression (MVD) is widely accepted as the effective therapy for hemifacial spasm (HFS) or trigeminal neuralgia (TN), the surgical treatment of coexistent HFS and TN in an individual is seldom addressed., Objective: To discuss the operative strategy of MVD for both the hemifacial and trigeminal nerves., Methods: Nine consecutive cases of coexistent HFS and TN caused by neurovascular confliction in the same side were studied. Except for one, the patients suffered from HFS followed by ipsilateral TN. All patients underwent MVD and were followed up for 3 to 30 months. Each surgery was analyzed retrospectively., Results: Intraoperatively, a looped vertebral artery (VA) shifted to the suffered side was found in 8 patients. The VA was regarded as the direct or indirect offending artery. After MVDs, the spasm ceased immediately in 6 patients; the other 3 patients had delayed relief within 3 months. The pain disappeared immediately in 7 of 9 patients. One patient felt relief after a week, and 1 had pain but improved slightly. No recurrence or complication was found., Conclusion: A shifted VA loop may account for this tic convulsif syndrome. MVD is a reasonable and effective therapy with a high cure rate for the disease. The key to the surgery is to move the VA proximally. The dissection should be performed rostrally starting from the caudal cranial nerves.

Objective: The root exit zone (REZ) of the seventh cranial nerve has been the target of microvascular decompression surgery (MVD) while searching the neurovascular conflict for treatment of hemifacial spasm for long time. Recently, increasing cases regarding the offending vessel beyond the REZ have been reported. To verify whether a thorough dissection of the nerve may give rise to a better postoperative result without enhancing complications, we conducted a parallel investigation., Patients and Methods: 112 Connective entire-nerve-exposed MVDs were performed and compared to 186 REZ-exposed MVDs performed by the same group of surgeons in 2009. The surgical findings, postoperative outcomes and complications as well as microscopic operating time were examined., Results: Immediately after the surgery, the outcomes were excellent in 98.2%, good in 1.8% and poor in 0% in the entire-nerve-exposed group, compared to excellent in 92.5%, good in 1.6% and poor in 5.9% in the REZ-exposed group. The difference of outcomes between the two groups were statistically significant (χ(2)=4.6845, P=0.0304), but not the complications and microscopic operating time. Nine of the 11 poor-outcome patients from the REZ-exposed group were then reoperated on within a few days, and their symptoms disappeared in eight patients. The main reason for the failed surgeries was that the offending vessels beyond REZ were missed., Conclusions: These findings suggested that the entire-root-decompression technique is recommended while performing MVDs in patients with hemifacial spasm., (Copyright © 2010 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.)

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., (Copyright © 2011 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.)

Background: Although the microvascular decompression (MVD) has become a definitive treatment for the primary hemifacial spasm (HFS), there still are some failed cases. To obtain a satisfactory postoperative outcome, those failure cases of MVD need to be analyzed., Method: Between January and October 2009, 393 patients with primary HFS underwent MVD. Postoperatively, 375 presented complete spasm-free, 7 improved apparently, and 11 without any improvement at all. A reoperation was performed in 9 of the 11 patients who had poor outcome within 5 days. Those redo MVD cases were reviewed., Findings: After the reoperation, the symptom of those patients all disappeared immediately. Therefore, the final outcomes were excellent in 97.7%, good in 1.8%, and poor in 0.5%. Up to the 1 year follow-up period, neither recurrence nor change was found. For the two patients without reoperation, their symptoms remained. The previous surgery was a failure due to insufficient decompression in two and conflict missed in seven., Conclusions: A successful MVD operation is attributable to a thorough exploration of the entire nerve course. An early relief should become the ambition of the operator while performing MVD.

Background and Objectives: 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., Methods: 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., Results: 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., Conclusions: 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.

Background: As an etiological treatment of trigeminal neuralgia (TN) and hemifacial spasm (HFS), microvascular decompression (MVD) has been popularized around the world. However, as a functional operation in the cerebellopontine angle (CPA), this process can be risky and the postoperative outcomes might not be good enough sometimes. Objective: In order to obtain a better result with less complication, this surgery should be further addressed. Methods: With experience of more than 4000 MVDs, we have gained knowledge about the operative technique. Through abundant intraoperative photos, each step of the procedure was demonstrated in detail and the surgical strategy was focused. Results: The principle of MVD is to separate the nerve-vessel confliction rather than isolate it with prostheses. A prompt identification of the conflict site is important, which hinges on a good exposure. A satisfactory working space can be established by an appropriate positioning of the patient's head and a proper craniectomy as well as a rational approach. A sharp dissection of arachnoids leads to a maximal visualization of the entire intracranial course of the nerve root. All the vessels contacting the trigeminal or facial nerve should be treated. Intraoperative electrophysiological mentoring is helpful to distinguish the offending artery for hemifacial cases. Conclusion: MVD is an effective treatment for the patient with TN or HFS. Immediate relief can be achieved by an experienced neurosurgeon with good knowledge of regional anatomy. A safe surgery is the tenet of MVD, and accordingly, no single step of the procedure should be ignored. [ABSTRACT FROM AUTHOR]