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

Factors Related to Hemifacial Spasm Recurrence in Patients Undergoing Microvascular Decompression—A Systematic Review and Meta-Analysis

There is a lack of knowledge about the factors associated with the recurrence of hemifacial spam (HFS) following an initially successful microvascular decompression (MVD) surgery. The aim of the present study was to systematically review the pertinent literature and carry out a meta-analysis of factors linked to HFS recurrence in patients undergoing initially successful MVD treatment. An online literature search was launched on the PubMed/Medline and Scopus databases. The following data were collected: sex, age at surgery, affected side, reported improvement after surgery, presence of post-operatory facial weakness, symptom duration, offender vessels, and data obtained from intraoperative neurophysiological monitoring. Upon full-text review, eight articles were included, studying 1105 patients, of which 64 (5.7%) reported recurrence after MVD surgery for hemifacial spasm. There was a statistically significant increased incidence of HFS recurrence in patients with the persistence of lateral spread response (LSR after surgery (OR 9.44 (95% CI 1.69–52.58) p 0.01), while those patients experiencing a shorter disease duration before going to surgery were significantly less prone to experiencing disease recurrence (OR 0.11 (95% CI 0.03–0.46) p 0.002). The remaining examined factors did not result as significantly associated with the risk of recurrence. The funnel plots were largely symmetrical for each variable studied. Taken together, the results of our meta-analysis seem to suggest that short-term symptom duration is a protective factor against HFS recurrence after MVD surgery, while LSR persistence is a negative prognostic factor. Well-designed randomized controlled clinical trials with a long follow-up are expected to further explore therapeutic alternatives for HFS recurrence.

Usefulness of intraoperative monitoring in microvascular decompression for hemifacial spasm: a systematic review and meta-analysis

OBJECTIVE

To review the diagnostic accuracy and possible added value of Brainstem Auditory Evoked Potentials (BAEP) monitoring and Lateral Spread Response (LSR) monitoring in microvascular decompression surgery for hemifacial spasms.

METHODS

For this systematic review we followed the PRISMA guidelines. We searched different databases and bibliographies of articles. We included studies on BAEP and LSR monitoring that reported data on hearing outcome or efficacy. Selected studies were assessed for bias using the MINORS tool.

RESULTS

64 articles were selected for qualitative synthesis, 42 met inclusion criteria for meta-analysis. The overall incidence of hearing loss was 3.4%. For BAEP monitoring AUC and pooled OR with 95% confidence interval were 0.911 (0.753-0.933) and 7.99 (3.85-16.60) respectively. Short-term data on LSR monitoring showed an overall spasm relief rate of 89% with pooled OR, sensitivity and specificity with a 95% confidence interval of 8.80 (4.82-16.08), 0.911 (0.863-0.943) and 0.451 (0.342-0.564) respectively. Long-term data on LSR monitoring showed an overall spasm relief rate of 95% with pooled OR, sensitivity and specificity with a 95% confidence interval of 4.06 (2.15-7.64), 0.871 (0.817-0.911) and 0.39 (0.294-0.495) respectively.

CONCLUSION

The alarm criteria, a wave V latency prolongation of 1ms or a wave V amplitude decrement of 50%, proposed by the 'American Clinical Neurophysiology Society' are a sensitive predictor for postoperative hearing loss. Other BAEP wave changes, for example, complete loss of wave V, are more specific but correspond to irreversible damage and are therefore not useful as warning criteria. LSR monitoring has high diagnostic accuracy at short-term follow-up. At long-term follow-up, diagnostic accuracy decreases because most patients get spasm relief regardless of their LSR status. LSR persistence after surgery has a good long-term outcome, as long as an extensive exploration of the facial nerve has been performed.

Predicting Early Loss of Lateral Spread Response before Decompression in Hemifacial Spasm Surgery

Recent studies have shown the evocation of lateral spread response (LSR) due to the compression of the facial nerve in hemifacial spasm (HFS). Intraoperative monitoring (IOM) of LSR could help locate neurovascular conflicts and confirm adequate micro-vascular decompression (MVD) while treatment of hemifacial spasm (HFS). However, studies on early LSR loss before decompression in HFS surgery are sparse, indicating the need to understand various perceptions on it. Therefore, we retrospectively analyzed 50 adult HFS patients who underwent MVD during the period of September 2018–June 2021. We employed IOM combining traditional LSR (tLSR) and dual LSR (dLSR). One patient was excluded owing to the lack of LSR induction throughout the surgery, while 49 were divided into groups A (n = 14) and B (n = 35), designated as with or without early LSR loss groups, respectively, and offending vessels were analyzed. The mean age of group A patients was significantly younger (47.8 ± 8.6) than that of group B (53.9 ± 10.6) (p = 0.0393). The significant predominating offending vessel in group A was the anterior inferior cerebellar artery (AICA, 78.57%). However, group B included those with AICA (28.57%), posterior inferior cerebellar artery (PICA, 22.86%), vertebral artery (VA) involved (25.71%), and combined AICA and PICA (22.86%). Group B exhibited poorer clinical outcomes with more complications. Conclusively, early LSR loss might occur in the younger population, possibly due to the AICA offending vessel. The compression severity of offending vessels may determine the occurrence of early LSR loss.

How to Improve the Effect of Microvascular Decompression for Hemifacial Spasm: A Retrospective Study of 32 Cases with Unsuccessful First Time MVD

BACKGROUND

 Microvascular decompression (MVD) has become accepted as an effective therapeutic option for hemifacial spasm (HFS); however, the curative rate of MVD for HFS varies widely (50-98%) in different medical centers. This study could contribute to the improvement of the MVD procedure.

METHODS

 We retrospectively analyzed 32 patients in whom initial MVD failed in other hospitals and who underwent a second MVD at our center. The clinical characteristics, operative findings, outcome of the second MVD, and complications were recorded.

RESULTS

 There were 18 women and 14 men (56.3 and 43.7%, respectively). The left-to-right ratio was 19:13. The mean age of the patients was 59.8 years. We found an undiscovered conflict site located in zone 4 in 10 patients and in the root entry zone in 8 patients. The initial MVD failed in nine patients because of ignorance of the arterioles that originate from the anterior inferior cerebellar artery. There were no special findings in four patients. No Teflon felts were found in the whole surgical field in one patient.

CONCLUSION

 Omission of the offending vessel is the most common cause of an unsuccessful MVD. Intraoperative abnormal muscle response associated with the Z-L response is a good measure to correctly identify the involved arterioles.

Predicting outcome of hemifacial spasm after microvascular decompression with intraoperative monitoring: A systematic review

BACKGROUND

Microvascular decompression has been established as a primary treatment for hemifacial spasm. Intraoperative monitoring is used during the surgery to guide neurosurgeons to determine whether the decompression of facial nerve from the vessel is sufficient. We performed a systematic review to assess the role of lateral spread response (LSR) monitoring in predicting hemifacial spasm outcomes after microvascular decompression.

METHOD

A systematic search of PubMed, ScienceDirect, Cochrane, and Google Scholar was conducted. We included studies that performed microvascular decompression surgery with intraoperative monitoring analyzing the correlation between lateral spread response and spasm relief. A critical appraisal was conducted for selected studies.

RESULT

Twenty-two studies comprising 6404 cases of hemifacial spasm, which underwent microvascular decompression surgery with intraoperative monitoring, were included. Of 15 articles that assessed symptoms shortly after surgery, 12 studies showed a significant correlation between lateral spread response resolution and disappearance of spasm. Four of six studies that evaluated the outcome at 3-month follow-up showed significant relationship between LSR and outcome, so did five of six articles that assessed spasm relief at 6-month follow-up. As much as 62.5% of studies (10 of 16) showed the result at long-term follow-up (≥1-year) was not significant.

CONCLUSION

Intraoperative monitoring during microvascular decompression surgery can be a useful tool to predict hemifacial spasm resolution. Though long-term outcomes of patients with LSR relief and persistence are similar, resolution of symptoms shortly after surgery will provide comfort to patients thereby improving their quality of life.

Persistent abnormal muscle response after microvascular decompression for hemifacial spasm

To explore the causes of persistent abnormal muscle response (AMR) after microvascular decompression (MVD) for hemifacial spasm (HFS) and the clinical outcomes of these patients. MVDs performed in Nanjing Drum Tower Hospital in 2017 were retrospectively studied, and 326 patients with HFS were classified into two groups based on whether AMR disappeared or persisted following MVD. The clinical features, treatment efficacy and postoperative complications were compared between the two groups. 305 patients with disappeared AMR after decompression were classified as Group A. In Group B, the 21 patients exhibited persistent AMR after successful MVD. The preoperative duration of symptoms in Group B was significantly longer than that in Group A (P < 0.001), and no significant difference was identified between the two groups in terms of gender, side, age and offending vessels (P > 0.05). The immediate postoperative cure rate of Group A (88.9%)was significantly higher than that in Group B (28.6%, P < 0.001), furthermore, the two groups were not different in the long-term outcome and the incidence of surgical complications (P > 0.05). The long preoperative duration of HFS patients may account for persistent AMR after successful decompression, and it is more likely for these patients to get delayed cured, the long-term outcomes showed no difference compared to those in patients with disappeared AMR after MVD.

Spasm Freedom Following Microvascular Decompression for Hemifacial Spasm: Systematic Review and Meta-Analysis

BACKGROUND

Hemifacial spasm (HFS) is a debilitating disorder characterized by intermittent involuntary movement of muscles innervated by the facial nerve. HFS is caused by neurovascular compression along the facial nerve root exit zone and can be treated by microvascular decompression (MVD). The goal was to determine rates and predictors of spasm freedom after MVD for HFS.

METHODS

A literature search using the key terms "microvascular decompression" and "hemifacial spasm" was performed. The primary outcome variable was spasm freedom at last follow-up. Analysis was completed to evaluate for variables associated with spasm-free outcome.

RESULTS

A total of 39 studies including 6249 patients were analyzed. Overall spasm freedom rate was 90.5% (5652/6249) at a follow-up of 1.25 ± 0.04 years. There was no significant relationship between spasm freedom versus persistent spasm and age at surgery, timing of follow-up, gender, disease duration, side of disease, or vessel type. Spasm freedom was more likely after an initial surgery versus a redo MVD (odds ratio 4.16, 95% confidence interval 1.99-8.68; P < 0.01).

CONCLUSIONS

MVD works well for HFS with cure rates >90% at 1-year follow-up in 6249 patients from 39 studies. A significant predictor of long-term spasm freedom at 1 year was an initial MVD as compared to repeat MVD. The majority of published manuscripts on MVD for HFS are heterogeneous single-institutional retrospective studies. As such, a large-scale meta-analysis reporting outcome rates and evaluating significant predictors of spasm freedom provides utility in the absence of randomized controlled studies.

The Utility of Intraoperative Lateral Spread Recording in Microvascular Decompression for Hemifacial Spasm: A Systematic Review and Meta-Analysis

BACKGROUND

Microvascular decompression (MVD) is the surgical treatment of choice for hemifacial spasm (HFS). During MVD, monitoring of the abnormal lateral spread response (LSR), an evoked response to facial nerve stimulation, has been traditionally used to monitor adequacy of cranial nerve (CN) VII decompression.

OBJECTIVE

To assess the utility of LSR monitoring in predicting spasm-free status after MVD postoperatively.

METHODS

We searched PubMed, Web of Science, and Embase for relevant publications. We included studies reporting on intraoperative LSR monitoring during MVD for HFS and spasm-free status following the procedure. Sensitivity of LSR, specificity, diagnostic odds ratio, and positive predictive value were calculated.

RESULTS

From 148 studies, 26 studies with 7479 patients were ultimately included in this meta-analysis. The final intraoperative LSR status predicted the clinical outcome of MVD with the following specificities and sensitivities: 89% (0.83- 0.93) and 40% (0.30- 0.51) at discharge, 90% (0.84-0.94) and 41% (0.29-0.53) at 3 mo, 89% (0.83-0.93) and 40% (0.30-0.51) at 1 yr. When LSR persisted after MVD, the probability (95% CI) for HFS persistence was 47.8% (0.33-0.63) at discharge, 40.8% (0.23-0.61) at 3 mo, and 24.4% (0.13-0.41) at 1 yr. However, when LSR resolved, the probability for HFS persistence was 7.3% at discharge, 4.2% at 3 mo, and 4.0% at 1 yr.

CONCLUSION

Intraoperative LSR monitoring has high specificity but modest sensitivity in predicting the spasm-free status following MVD. Persistence of LSR carries high risk for immediate and long-term facial spasm persistence. Therefore, adequacy of decompression should be thoroughly investigated before closing in cases where intraoperative LSR persists.

Prognostic Value of Abnormal Muscle Response During Microvascular Decompression for Hemifacial Spasm: A Meta-Analysis

OBJECTIVE

To perform a comprehensive meta-analysis to systematically assess the value of abnormal muscle response (AMR) in predicting the surgical outcome of patients with hemifacial spasm.

METHODS

The electronic database PubMed, Embase, Web of Science, and ScienceDirect were searched, and relevant articles were identified up to September 30, 2019. These data were extracted for pooled analysis, heterogeneity testing, sensitivity analysis, publication bias analysis, and Fagan plot analysis.

RESULTS

The disappearance of AMR during microvascular decompression was associated with a favorable short-term surgical outcome (pooled relative risk [RR], 1.42; 95% confidence interval [CI], 1.24-1.62; pooled RR adjusted for publication bias, 1.30; 95% CI, 1.08-1.57). The corresponding pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 0.91 (95% CI, 0.88-0.94), 0.34 (95% CI, 0.27-0.42), 1.4 (95% CI, 1.2-1.6), 0.26 (95% CI, 0.17-0.38), and 5 (95% CI, 3-9), respectively. The disappearance of AMR was almost ineffective in predicting the long-term surgical outcome (pooled RR, 1.09; 95% CI, 1.02-1.17; pooled RR adjusted for publication bias, 1.001; 95% CI, 0.92-1.09). The corresponding pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 0.90 (95% CI, 0.85-0.93), 0.28 (95% CI, 0.20-0.37), 1.2 (95% CI, 1.1-1.4), 0.38 (95% CI, 0.22-0.63), and 3 (95% CI, 2-6), respectively.

CONCLUSIONS

The disappearance of AMR during microvascular decompression demonstrates limited prognostic value for a favorable short-term outcome, and does not appear effective in predicting the long-term outcome of patients with hemifacial spasm.

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

BACKGROUND

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 the facial nerve to increase the positive AMR detection rate.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Blink synkinesis monitoring during microvascular decompression for hemifacial spasm

BACKGROUND

In the present study, we investigated whether blink synkinesis monitoring during microvascular decompression (MVD) is effective for predicting long-term outcomes in patients with hemifacial spasm (HFS).

METHODS

This retrospective study included 69 patients who had undergone MVD for HFS at a tertiary hospital. All patients underwent intraoperative monitoring of blink synkinesis, lateral spread responses (LSRs), and facial nerve motor-evoked potentials (FNMEPs). Baseline signals were compared to those obtained following decompression with Teflon, and postoperative outcomes were recorded.

RESULTS

A total of 65 patients were observed with complete relief of symptoms after 1 year after MVD, while 61 patients were observed with initial disappearance of blink synkinesis, 57 patients were observed with initial elimination of the LSR, and 45 patients with initial decreases in FNMEP amplitude (>50%). The highest sensitivity and accuracy values were observed for blink synkinesis. Chi-square tests comparing the sensitivity of the three methods revealed that FNMEP monitoring was associated with significantly lower sensitivity values than the remaining methods. Combined use of blink synkinesis and LSRs did not significantly increase sensitivity (61/65 vs 62/65) or accuracy (62/69 vs 63/69).

CONCLUSION

Our results demonstrate that blink synkinesis monitoring is safe during MVD for HFS. Furthermore, blink synkinesis was associated with the highest sensitivity and predictive values among the three methods evaluated. These findings suggest that blink synkinesis can be regarded as the first choice for intraoperative monitoring during MVD. Concurrent use of blink synkinesis and LSR monitoring may maximize the ability to predict patient prognosis and determine the extent of decompression.

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.

An investigation into quality of life improvement in patients undergoing microvascular decompression for hemifacial spasm

OBJECTIVE Hemifacial spasm (HFS) is a movement disorder characterized by involuntary spasms of the facial muscles, and it can negatively impact quality of life (QOL). This retrospective study and systematic review with meta-analysis was conducted to investigate the QOL in patients with HFS following intervention with microvascular decompression (MVD) and botulinum toxin (BT). METHODS In the retrospective analysis, a QOL questionnaire was administered to all patients undergoing MVD performed by a single surgeon. The QOL questionnaire included unique questions developed based on the authors' experience with HFS patients in addition to the health-related QOL HFS-8 questionnaire. The authors also report on a systematic review of the English literature providing outcomes and complications in patients with HFS undergoing treatment with either MVD or BT. RESULTS Regarding the retrospective analysis, 242 of 331 patients completed the questionnaire. The mean score of the 10 QOL questions improved from 22.78 (SD 9.83) to 2.17 (SD 5.75) following MVD (p < 0.001). There was significant improvement across all subscales of the questionnaire between pre- and postoperative responses (p < 0.001). Regarding the systematic review, it is reported that approximately 90% of patients undergoing MVD for HFS experience a complete recovery from symptoms, whereas the mean peak improvement of symptoms following treatment with BT is 77%. Furthermore, patients undergoing MVD reported a greater improvement in the mean supplemental index of QOL as compared with patients receiving BT therapy. CONCLUSIONS Microvascular decompression offers a significant improvement in QOL in well-selected patients suffering from HFS, and may offer an increased benefit for QOL over BT injections.

Failed microvascular decompression surgery for hemifacial spasm: a retrospective clinical study of reoperations

BACKGROUND

To investigate the repeat microvascular decompression on hemifacial spasm patients who failed the first MVD.

METHODS

Twenty-six patients underwent late redo MVD in our institution from January 1, 2011 to December 31, 2015. The clinical features, surgical findings, outcomes, and complications of the repeat MVD were analyzed retrospectively.

RESULTS

Twenty-four (92.3 %) patients were cured immediately after the redo MVD. Delayed relief was found in two (7.7 %) patients; it took 6 days and 2 weeks for them to obtain complete relief. No recurrence was found during follow-up. Surgical complications including three (11.5 %) facial paralysis and one (3.8 %) hearing loss.

CONCLUSIONS

We suggested that repeat MVD can be performed 2 years after the first MVD if the spasm was not resolved. Repeat MVD for HFS is effective.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

An optimized abnormal muscle response recording method for intraoperative monitoring of hemifacial spasm and its long-term prognostic value

BACKGROUND

Intraoperative electrophysiological monitoring is used to determine whether decompression is sufficient during microvascular decompression (MVD) for hemifacial spasm (HFS). However, the real offending vessel is sometimes neglected by the neurosurgeons. Here, we reported our experience in using optimized abnormal muscle response (AMR) monitoring and continuous intraoperative monitoring for MVD.

METHODS

This study included 2161 HFS patients who underwent MVD using traditional (1023 patients) and optimized (1138 patients) methods. Modified AMR monitoring was adopted in our study, with the zygomatic branch of the facial nerve stimulated and the temporal branch, buccal branch, marginal mandibular branch and cervical branch of the facial nerve detected for AMR. These cases were analyzed retrospectively with emphasis on the postoperative outcomes and intraoperative findings. The therapeutic effect was evaluated at day 1, month 3 and year 1 after operation.

RESULTS

The relief rate at day 1, month 3 and year 1 after operation for patients who employed optimized AMR recording method was 95.1%, 97.4% and 99.3%, comparing with 92.2%, 95.0% and 97.8% in traditional method. There was significant difference in achieved immediate remission and recovery rate during 12-month follow-up between the two groups (P < 0.05). The modified intraoperative monitoring showed the sensitivity of AMR disappearance to judge the relief at day 1, month 3 and year 1 after HFS operation was 95.7%, 96.3% and 97.3%, respectively; the specificity was 44.6%, 43.3% and 50.0%, respectively; the accuracy was 93.1%, 94.9% and 97.4%, respectively.

CONCLUSIONS

Our findings demonstrated that the optimized method could improve the positive detection rate of AMR and accuracy of decompression effect prediction. The evaluation for the decompression effect by optimized intraoperative monitoring can increase the immediate remission rate and reduce the delayed recovery rate.

Indications and Timings of Re-operation for Residual or Recurrent Hemifacial Spasm after Microvascular Decompression: Personal Experience and Literature Review

We reviewed reports about the postoperative course of hemifacial spasm (HFS) after microvascular decompression (MVD), including in our own patients, and investigated treatment for delayed resolution or recurrence of HFS. Symptoms of HFS disappear after surgery in many patients, but spasm persists postoperatively in about 10-40%. Residual spasm also gradually decreases, with rates of 1-13% at 1 year postoperatively. However, because delayed resolution is uncommon after 1 year postoperatively, the following is advised: (1) In patients with residual spasms after 1 year postoperatively (incomplete cure) or who again experience spasm ≥ 1 year postoperatively (recurrence), re-operation is recommended if the spasms are worse than before MVD. (2) When re-operation is considered, preoperative magnetic resonance imaging (MRI) findings and intraoperative videos should be reviewed to ensure that no compression due to a small artery or vein was missed, and to confirm that adhesions with the prosthesis are not causing compression. If any suspicious findings are identified, the cause must be eliminated. Moreover, because of the risk of nerve injury, decompression of the distal portion of the facial nerve should be performed only in patients in whom distal compression is strongly suspected to be the cause of symptoms. (3) Cure rates after re-operation are high, but complications such as hearing impairment and facial weakness have been reported in 10-20% of cases, so surgery must be performed with great care.

Clinical impact of residual lateral spread response after adequate microvascular decompression for hemifacial spasm: A retrospective analysis

OBJECTIVE

Residual lateral spread response (LSR) after seemingly adequate decompression for hemifacial spasms (HFSs) can provide prognostic information about the outcome of microvascular decompression (MVD). In the present study, the main objective was to evaluate the clinical and prognostic impact of residual LSR after adequate MVD for HFS.

METHODS

An observational study was conducted in patients who underwent MVD for HFS at the University of Pittsburgh Medical Center between January 2000 and December 2007. Clinical and neurophysiological outcomes after pre- and post-MVD, including spasm relief, amplitude and latency of LSR, and postoperative complications were collected from groups with and without residual LSR after adequate decompression. Data analysis was performed to see the impact of residual LSR on HFS outcomes.

RESULTS

There was no significant difference in preoperative clinical characteristics as well as postoperative complications between the two groups. The patient had significantly higher spasm relief in immediate postoperative period (p = 0.01) and at discharge (p = 0.002) when LSR disappeared during the procedure. There is no difference in spasm relief at follow-up period between the two groups (p = 0.69).

CONCLUSION

Lateral spread is an invaluable tool in MVD for HFSs. Adequate decompression in patients with residual LSR improved long-term spasm relief. Constant communication between neurophysiologists and the surgeon might be vital to achieve adequate decompression. The amplitude of residual LSR after adequate decompression does not significantly affect the long-term spasm relief.

Microvascular decompression under neuroendoscopic view in hemifacial spasm: rostral-type compression and perforator-type compression

We report microvascular decompression (MVD) under neuroendoscopic view in hemifacial spasm (HFS) patients with rostral- and perforator-type compression of the root exit zone (REZ) of the facial nerve. Using either a wireless iPad Mini as a monitor on the microscope or a high-resolution monitor, microscopic and endoscopic views enabled MVD for complete cure of HFS with rostral-type compression (the offender compressing the REZ on the opposite rostral side to the operative approach) or perforator-type compression (the offender tethered to the REZ by the perforator). MVD under neuroendoscopic view may offer more accurate MVD and complete resolution of HFS.

A comparison of three induction regimens using succinylcholine, vecuronium, or no muscle relaxant: impact on the intraoperative monitoring of the lateral spread response in hemifacial spasm surgery: study protocol for a randomised controlled trial

BACKGROUND

Surgical microvascular decompression (MVD) is the curative treatment for hemifacial spasm (HFS). Monitoring MVD by recording the lateral spread response (LSR) intraoperatively can predict a successful clinical outcome. However, the rate of the LSR varies between trials, and the reason for this variation is unclear. The aim of our trial is to evaluate the rate of the LSR after intubation following treatment with succinylcholine, vecuronium, or no muscle relaxant.

METHODS AND DESIGN

This trial is a prospective randomised controlled trial of 96 patients with HFS (ASA status I or II) undergoing MVD under general anaesthesia. Patients are randomised to receive succinylcholine, vecuronium, or no muscle relaxant before intubation. Intraoperative LSR will be recorded until dural opening. The primary outcome of this study is the rate of the LSR, and the secondary outcomes are post-intubation pharyngolaryngeal symptoms, the rate of difficult intubations, the rate of adverse haemodynamic events and the relationship between the measurement of LSR or not, and clinical success rates at 30 days after surgery.

DISCUSSION

This study aims to evaluate the impact of muscle relaxants on the rate of the LSR, and the study may provide evidence supporting the use of muscle relaxants before intubation in patients with HFS undergoing MVD surgery.

TRIALS REGISTRATION

http://www.chictr.org/ ChiCTR-TRC-11001504 Date of registration: 24 June, 2011. The date the first patient was randomised: 30 September, 2011.