Significant Correlation between Delayed Relief after Microvascular Decompression and Morphology of the Abnormal Muscle Response in Patients with Hemifacial Spasm

Intraoperative use of lateral spread response measurement in the upper orbicularis oculi and mandibular muscles in patients with hemifacial spasm after botulinum toxin treatment

BACKGROUND

Following repeated botulinum toxin (BTX) treatments, patients with hemifacial spasm (HFS) are recommended to undergo microvascular decompression (MVD) for a permanent cure. Intraoperative lateral spread response (LSR) monitoring is important to improve surgical outcomes. However, LSR monitoring during MVD surgery in HFS patients who have previously received BTX is challenging, since the muscles typically used to assess the LSR are paralyzed. Here, we describe our use of the upper part of the orbicularis oculi and mentalis muscles for intraoperative monitoring of the LSR during MVD in HFS patients following BTX treatment.

METHODS

HFS patients who underwent MVD surgery were divided into two groups based on their history of BTX treatment: BTX+ and BTX- groups. In the BTX+ group, MVD was performed at least 3 months after the last BTX injection. We measured LSR morphology, including the number of spikes, their duration, and maximum amplitude in all patients. We also measured intraoperative LSR disappearance rate, and the cure rate of HFS at the final follow-up (over 1 year after surgery).

RESULTS

Although the waveforms showed a trend toward shorter durations with mandibular branch stimulation in the BTX+ group, there was no difference in the number of spikes or maximum amplitude values. There was no increase in LSR dysmetria after BTX treatment (BTX+ group: 32.8% vs. BTX- group: 31.9%). There was also no difference in intraoperative LSR disappearance rate between the two groups (BTX+ group: 68.3% vs. BTX- group: 74.6%).

CONCLUSION

Intraoperative LSR monitoring using the upper part of the orbicularis oculi muscle and the mentalis muscle at an interval of at least 3 months after the last BTX treatment might be a feasible monitoring technique during MVD for HFS.

Lateral Spread Response in Hemifacial Spasm: Physiological Mechanisms, Intraoperative Utility, and Prognostic Significance

Facial nerve compression by blood vessels near the brainstem can cause hemifacial spasm (HFS). There are two treatment options for this condition: botulinum toxin and surgical microvascular decompression (MVD). During microvascular decompression, the facial nerve is separated from the offending vessel, and intraoperative neuromonitoring in these patients demonstrates abnormal muscle response (AMR), which is known as the lateral spread response (LSR). Though the disappearance of lateral spread response is a hallmark of successful microvascular decompression, little information is available about its physiological origin and diagnostic utility. In the present review, we have attempted to address the aforementioned caveats about lateral spread response with an emphasis on the intraoperative utility and diagnostic role of this electrophysiological phenomenon.

Clinical analysis of abnormal muscle response monitoring for hemifacial spasm during microvascular decompression: a retrospective study

BACKGROUND

Microvascular decompression (MVD) is a widely recognized therapeutic approach for the treatment of hemifacial spasm (HFS). Abnormal muscle response (AMR) is a distinctive electromyographic finding exclusively in patients with HFS. The purpose of our investigation was to determine the correlation between changes in intraoperative AMR and surgical efficacy, as well as the incidence of postoperative complications in patients with HFS after undergoing MVD.

METHODS

In this retrospective study, we evaluated 145 patients with HFSs treated with MVD, which was maintained for 1 year postoperatively. The subjects were divided into two groups based on the persistence or disappearance of AMR. Continuous monitoring of AMR during surgery provided data on persistence. All patients were followed up 1 day, 30 days, and 1 year after MVD. A range of potential predictive factors, such as patient demographics, symptom duration, and morphology and latency of AMR, were analyzed using binary logistic regression to assess their relationship with postoperative non-cure and delayed cure rates.

RESULTS

The 1 day postoperative cure rate was 77.9%, with a 1 year postoperative cure rate of 94.59% and 1 day postoperative relief rate of 87.6%. A marked distinction was noted between preoperative and 1 year postoperative Cohen grades (P < 0.05). Moreover, 1 day after surgery, the outcome demonstrated significant variability, as shown by the binary logistic regression model (χ2 = 62.913, P < 0.05). The results suggested that factors such as age, symptom duration, disappearance of AMR, and preoperative carbamazepine treatment markedly influence outcomes 1 day after surgery. The binary logistic regression model for delayed cure at 1 year showed significant variability (χ2 = 54.883, P < 0.05). Furthermore, analysis using generalized estimating equations revealed that the duration of postoperative follow-up significantly impacted Cohen grades, as did the disappearance of AMR, with the grade of AMR disappearance being only 10% of that of non-AMR disappearance (P < 0.05).

CONCLUSION

Our findings suggest that MVD is an effective intervention for HFS. Our findings also indicate that factors such as patient age, duration of symptoms, disappearance of AMR, and preoperative carbamazepine therapy are significant predictors of 1 day postoperative cure rate. Major predictors for delayed cure at 1 year include age, symptom duration, AMR disappearance, preoperative carbamazepine and botulinum neurotoxin administration, single morphology AMR, and offending vertebral artery.

Impact of offending vessel location on lateral spread response variations in hemifacial spasm patients

Objective

This study aims to investigate the impact of the offending vessel's compression location on intraoperative lateral spread response (LSR) waveform parameters during microvascular decompression (MVD) for hemifacial spasm (HFS). Additionally, the study evaluates the clinical significance of LSR variations in intraoperative electrophysiological monitoring.

Methods

A retrospective analysis was conducted on 72 patients with HFS who underwent MVD at Nanjing Brain Hospital between September 2021 and September 2023. Patients were categorized into two groups based on the compression site of the offending vessel on the facial nerve: the transitional zone (TZ) group and the attached segment (AS) group. General clinical characteristics, intraoperative LSR parameters, and postoperative outcomes were compared between groups. Statistical analyses focused on LSR latency, amplitude, and duration, as well as the patterns of LSR disappearance and postoperative complications.

Results

The TZ group comprised 31 patients, while the AS group included 41. No significant differences were observed in baseline characteristics between groups. Intraoperative monitoring revealed that LSR disappearance was more frequently incomplete in the TZ group (11.1%) than in the AS group (p < 0.05). LSR latency was significantly longer in the AS group (p < 0.001), while the amplitude in the orbicularis oculi muscle was lower in the TZ group (p < 0.001). Additionally, LSR duration (T2) in the orbicularis oris (p < 0.05) and mentalis muscles (p < 0.01) was longer in the AS group, though the amplitude differences were not statistically significant. Postoperative outcomes showed no significant difference in effectiveness between the groups (AS: 92.7% vs. TZ: 93.5%, p = 0.882). Complications, such as facial palsy and hoarseness, were slightly more common in the AS group, whereas hearing loss and ataxia were more frequent in the TZ group. However, none of these differences reached statistical significance.

Conclusion

The compression location of the offending vessel significantly influences LSR parameters, with longer latency and prolonged duration observed in the AS group. Despite these variations, postoperative outcomes and complications were comparable between groups. These findings highlight the importance of considering the compression location during MVD and the potential value of LSR monitoring in guiding surgical decision-making.

Correlation between Delayed Relief after Microvascular Decompression and Morphology of the Lateral Spread Response in Patients with Hemifacial Spasm-Temporal versus Mandibular Branch Stimulation

Although microvascular decompression (MVD) is a reliable treatment for hemifacial spasm (HFS), delayed postoperative relief is one of its main issues. We previously evaluated the morphology of the lateral spread response (LSR) and reported the correlation between delayed relief after MVD and polyphasic morphology of the LSR. The purpose of this study was to investigate the correlation between the morphology of the LSR with stimulation of the temporal and mandibular branches of the facial nerve and delayed relief of persistent HFS after MVD. We retrospectively analysed and compared data from 49 of 205 consecutive patients who underwent MVD for HFS at our hospital between January 2015 and March 2022. Based on the pattern of the initial LSR morphology, patients were divided into 4 groups (LSR with temporal branch stimulation/LSR with mandibular branch stimulation; polyphasic/polyphasic group, polyphasic/monophasic group, monophasic/polyphasic group, monophasic/monophasic group). The results of MVD surgery for HFS were evaluated 1 week, 1 month and 1 year postoperatively, by evaluating whether or not the symptoms of HFS persisted at the time of each follow-up. We found significant differences in residual postoperative HFS 1 week postoperatively among the 4 groups (p < 0.05), as assessed using m*n Yates chi-square test. There is a significant correlation between delayed relief after MVD and polyphasic morphology of the initial LSR in patients with HFS. The LSR with temporal rather than mandibular branch stimulation might be useful for predicting delayed relief following MVD in HFS patients.

Correlation between Delayed Relief after Microvascular Decompression and Morphology of the Lateral Spread Response in Patients with Hemifacial Spasm-Further Examination with Compound Motor Action Potentials

Although microvascular decompression (MVD) is a reliable treatment for hemifacial spasm (HFS), postoperative delayed relief is one of its main issues. We previously evaluated the morphology of the lateral spread response (LSR) and reported correlation between delayed relief after MVD and polyphasic morphology of the LSR. This study aimed to investigate the morphology of LSR and the course of recovery of the compound motor action potential (CMAP), to better understand the pathophysiology of delayed healing of HFS. Based on the pattern of the initial LSR morphology on temporal and marginal mandibular branches stimulation, patients were divided into two groups: the monophasic and polyphasic groups. The results of MVD surgery and sequential changes in the CMAP were evaluated 1 week, 1 month, 1 year, and final follow-up after the surgery. Significantly higher rates of persistent postoperative HFS were observed in patients with the polyphasic type of initial LSR at 1 week and 1 month after the surgery (P < 0.05, respectively). In the polyphasic group, the amplitude of the CMAP tended to gradually improve with time, while in the monophasic group, the amplitude of the CMAP decreased on the seventh postoperative day, followed by its gradual improvement. There is a significant correlation between delayed relief after MVD and polyphasic morphology of the initial LSR in patients with HFS. In the polyphasic group, CMAP recovered earlier and showed less reduction in amplitude, suggesting segmental demyelination, with less damage to peripheral nerves.

Microvascular decompression for hemifacial spasm after Bell's palsy: a retrospective clinical study

OBJECTIVE

This study aimed to investigate the clinical characteristics of hemifacial spasm (HFS) after Bell's palsy and to evaluate the therapeutic efficacy of microvascular decompression (MVD).

METHODS

A retrospective analysis was conducted on 18 patients who underwent MVD for HFS after Bell's palsy at our institution between January 1, 2017, and December 31, 2021. Clinical presentations, intraoperative findings, postoperative outcomes, and complications were comprehensively assessed.

RESULTS

Neurovascular compression (NVC) was identified in all the 18 patients. The offending vessels included anterior inferior cerebellar artery (AICA) in 6 patients (33.3%), posterior inferior cerebellar artery (PICA) in 7 patients (38.9%), vertebral artery (VA) combined with AICA in 3 patients (16.7%), and VA alongside PICA in 2 patients (11.1%). Notably, marked arachnoid membrane adhesion was evident in 11 patients (61.1%). 15(83.3%) patients were cured immediately after MVD, delayed relief was found in 3 (16.7%) patients. During the follow-up period, recurrence was not documented. Surgical complications were limited to facial paralysis in 3 patients and auditory impairment in 1 patient. No additional surgical complications were recorded.

CONCLUSIONS

In patients manifesting HFS after Bell's palsy, NVC predominantly underlies the etiology. MVD is a reliably safe and efficacious therapeutic intervention.

Delayed complete remission of hemifacial spasms following microvascular decompression and the implications for optimal time of revision surgery

BACKGROUND

Microvascular decompression (MVD) is an effective method for directly treating hemifacial spasms (HFS). The timing for the consideration of failed MVD and reoperation has been paradoxical.

OBJECTIVE

This study aimed to investigate the delayed complete remission of HFS in terms of prevalence rate, duration between surgery and delayed complete remission, and predictive factors.

METHODS

A hundred patients with HFS who underwent MVD from 2012-2021 were enrolled in the study. All HFS occurred as a result of compression of the facial nerve by adjacent blood vessels. Clinical information, intraoperative findings, and surgical outcomes were incorporated for data analysis.

RESULTS

In the first week after MVD, 67 of 100 patients achieved complete remission of HFS, while the remaining 33 had incomplete remission. In long-term follow-up, 26 individuals gradually developed delayed complete remission with a median duration of 9.1 months. Finally, 86 of 100 patients achieved complete long-term remission. Recurrent HFS and incomplete remission were found in 7 and 7 patients, respectively. Factors associated with postoperative complete remission in the first week were a severe degree of facial nerve compression (p = 0.047, OR 2.75, 95% CI 1.01-7.40), with long-term complete remission was left-sided HFS (p = 0.012, OR 5.73, 95% CI 1.47-22.36), and with the appearance of delayed complete remission was the prolonged duration of HFS at least 3 years before MVD (p = 0.046, OR 3.75, 95% CI 1.03-13.76). Transient facial paresis was found in 11% of the patients. Of them, facial nerve function recovered completely in all cases.

CONCLUSIONS

A delayed complete remission of HFS could be expected in long-term follow-up after MVD and is probably related to a longer duration of HFS before surgery. Unnecessary reoperation should be avoided in the early years following the first surgery.

Hemifacial Spasm Caused by Vascular Compression of the Anterior Inferior Cerebellar Artery-Posterior Inferior Cerebellar Artery Common Trunk Anomaly at the Cisternal Portion of the Facial Nerve: A Case Report

W report the first case of hemifacial spasm (HFS) caused by vascular compression of the anterior inferior cerebellar artery (AICA)-posterior inferior cerebellar artery (PICA) common trunk anomaly at the cisternal portion of cranial nerve VII (CN VII). A 71-year-old female with a typical right HFS was admitted to our hospital. As per her magnetic resonance (MR) imaging results, no offending arteries were noted around the CN VII root exit zone (REZ). Computed tomography angiography revealed an AICA-PICA common trunk anomaly with a dominant PICA, with the rostral branch of the AICA-PICA common trunk anomaly compressing the CN VII at the cisternal portion. The patient underwent microvascular decompression (MVD), and the HFS disappeared after surgery. The amplitude of the abnormal muscle responses (AMR) disappeared immediately after complete transposition of the offending artery. However, the patient experienced mild transient facial palsy 3 days after MVD which was eventually resolved with the administration of vitamin B12. No HFS recurrence was observed during the 1-year follow-up period. The AICA-PICA common trunk anomaly has been found to cause HFS as it compressed the CN VII at the cisternal portion, and not at the REZ. AMR monitoring might be helpful for cases where the unusual vessel particularly compresses the CN VII.