Microvascular decompression to treat hemifacial spasm: long-term results for a consecutive series of 143 patients

Determining prognostic factors in the treatment of primary hemifacial spasm: Clinical outcomes and complications. A literature review

Objective

Primary Hemifacial Spasm (PHFS) significantly impacts quality of life, necessitating effective treatment like microvascular decompression of the facial nerve. This study aims to identify prognostic factors related to surgical treatment to enhance outcomes and minimize complications. A systematic review of literature from the past five years was conducted.

Methods

Following PRISMA guidelines, we systematically searched databases like PubMed, Embase, Scopus, Ovid, EBSCO, and Cochrane using keywords such as 'Hemifacial spasm,' 'Microvascular decompression,' 'Neurovascular conflict,' and 'Surgical techniques.' The search spanned January 2018 to November 2023. The 'Rayyan' program facilitated data compilation. Each author reviewed abstracts, applying inclusion criteria like systematic reviews, clinical trials, observational studies, and case series, while excluding theoretical or non-English articles.

Results

Of 26 selected articles, those solely addressing PHFS treatment with botulinum toxin and lacking surgical procedure data were excluded. Thus, our analysis focused on 16 articles, including meta-analyses, systematic reviews, clinical trials, and observational studies.

Discussion

Microvascular decompression at the cerebellar pontine angle is the mainstay treatment for hemifacial spasm. Despite limited statistically significant prognostic factors in the literature, overarching recommendations aim to improve outcomes, minimize complications, and prevent recurrences. Key considerations include surgeon expertise, precise techniques, thorough nerve exploration, identifying the conflict's cause, and intraoperative monitoring.

Conclusions

PHFS significantly impacts patients' lives, necessitating timely surgical intervention if initial treatments fail. While statistically significant prognostic factors may be lacking, this study highlights crucial considerations for successful treatment.

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.

Mapping trends in hemifacial spasm research: bibliometric and visualization-based analyses of the Web of Science Core Collection

Hemifacial spasm (HFS) is a common cranial nerve disease. In HFS research, we conducted a bibliometric analysis to examine the development and research trends. A retrieval of HFS studies published between 2011 and 2022 was performed from the Web of Science Core Collection in September 2022. Two scientometric tools were used to perform bibliometric and visualization-based analyses: VOSviewer and CiteSpace. Bibliometric analysis of 1461 studies published between 2011 and 2022 was carried out using data from 444 journals, 6021 authors, 1732 institutions, and 76 countries/regions. China, the USA, Japan, and South Korea were four key contributors to this study. Shanghai Jiaotong University was the major institution with the larger number of publications. Li Shiting was the most prolific author. Jannetta PJ was the most co-cited author. World Neurosurgery was the top prolific journal. Journal of Neurosurgery was the top co-cited journal. The top five keywords were hemifacial spasm, microvascular decompression, trigeminal neuralgia, surgery, and neurovascular compression. This study examines the research trends in global scientific research on HFS over the last decade. Researchers interested in learning more about current trends and novel research frontiers in this area can benefit from the study.

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.

Surgical treatment of hemifacial spasms: how to predict failure and complications through a series of 200 patients

Primary hemifacial spasm (pHFS) is a benign but disabling movement disorder caused by a neurovascular conflict involving the facial nerve. Surgical treatment by microvascular decompression (MVD) is the most effective therapeutic. Predictors of surgical failure and surgical complications are still lacking. The aim of this study is to identify such predictors through the retrospective analysis of a series of 200 consecutive patients. All patients who underwent MVD for pHFS from January 1991 to December 2017 were included. All patients had at least two years follow-up. In addition to the demographic data, the outcome and the complications were collected. The primary outcome analysis showed that 7.5% of patients had a recurrence. Multiple and AICA related neurovascular conflicts were statistically associated to a higher recurrence rate after MVD (respectively p < 0.001 and p = 0.02). Permanent facial palsy occurred in 2.5% of patients, hearing loss in 9.0% (2.0% of complete unilateral impairment) and dizziness in 2.5%. The risk of each of these peripheral neurological impairments was statistically increased by a long duration between the first pHFS symptom and the MVD (p < 0.001). In case of recurrence, a second MDV was offered. Long term follow-up showed that all patients had a complete resolution of the HFS. Post-operative complication rate was not significantly increased after a second MVD. Multiple and AICA related neurovascular conflicts are associated to a higher risk of surgical failure. When a pHFS recurrence occurs, a second surgical procedure is associated with excellent outcome without significant increase of post-operative complications and should therefore be recommended.

Outcomes after Microvascular Decompression for Hemifacial Spasm without Definite Radiological Neurovascular Compression at the Root Exit Zone

The purpose of this study was to investigate the outcome of microvascular decompression (MVD) in patients with hemifacial spasm (HFS) who have no definite radiological neurovascular compression (NVC). Sixteen HFS patients without radiological NVC on preoperative MRI underwent MVD surgery. The symptoms were left-sided in fourteen (87.5%) and right-sided in two patients (12.5%). Intraoperatively, the most common vessel compressing the facial nerve was the AICA (8, 44.4%), followed by arterioles (5, 27.8%), veins (4, 22.2%), and the PICA (1, 5.6%). The most common compression site was the cisternal portion (13, 76.5%) of the facial nerve, followed by the REZ (4, 23.5%). One patient (6.3%) was found to have multiple NVC sites. Arachnoid type (7, 50%) was the most common compressive pattern, followed by perforator type (4, 28.6%), sandwich type (2, 14.3%), and loop type (1, 7.1%). A pure venous compression was seen in two patients, while a combined venous-arterial "sandwich" compression was detected in two patients. Symptom improvement was observed in all of the patients. Only one patient experienced recurrence after improvement. Based on our experience, MVD surgery can be effective for primary HFS patients with no definite radiological NVC. MVD can be considered if the patient shows typical HFS features, although NVC is not evident on MRI.

Predictors of Multi-Vessel Identification, Outcome, and Optimal Surgical Timing for Microvascular Decompression in Hemifacial Spasm

OBJECTIVES AND BACKGROUND

Hemifacial spasm (HFS) is a disabling condition that imposes significant burden upon patients. Microvascular decompression (MVD) surgery is the most effective and long-lasting treatment for HFS, but outcomes following this surgery may vary based on a variety of clinical and operative factors. A more thorough understanding of the variables that impact patient outcome after MVD surgery is needed.

METHODS

A systematic review and meta-analysis of Medline, Embase, and Central was conducted (n = 2108 screened; n = 86 included) with the goal of determining the impact of the following variables on outcome: duration of disease, geographic location, intraoperative use of an endoscope, and intraoperative finding of single versus multi-vessel neurovascular compression.

RESULTS

Most cases of hemifacial spasm occur on the left side (53.9%, p < 0.001) and are more common in women than men (66.5% versus 33.5%, p < 0.0001). The offending vessel frequencies were: 40.8% anterior inferior cerebellar artery [AICA], 24.9% posterior inferior cerebellar artery [PICA], 17.2% multiple vessels, and 4.7% vertebral artery [VA]. Multiple vessel combinations involved: 26.5% PICA + AICA, 24.6% PICA + VA, 23.1% AICA + VA, and 4.7% AICA + PICA + VA. Relative to the Americas, AICA was less frequent in Europe (p = 0.005), while PICA more frequent in Europe (p = 0.009) and Asia (p < 0.0001). With endoscope assistance, frequency of multiple vessels identified was 31.7% (versus 14.7% with non-endoscopic, p = 0.005), and 27.4% for AICA (43.5% with non-endoscopic, p = 0.003). Spasm improvement was 94.1% near discharge and 96.0% at maximum follow-up. Complications occurred in 16.5% of cases, with spasm recurrence in 2.4%. Greatest frequency of spasm improvement (p < 0.0001) and lowest spasm recurrence rates (p = 0.0005) were reported in series from Asia. For every additional month of pre-operative spasm, the effect size of post-operative improvement decreased (p = 0.04). With every subsequent postoperative month, the effect size of spasm improvement increased (p = 0.0497). The frequency of spasm improvement was significantly higher in series published after 2005 (94.4% versus 97.4%, p = 0.005).

CONCLUSION

Clinical outcomes following MVD for HFS have improved since 2005. Consideration should be given to earlier operation (shorter disease duration) and use of an endoscope may increase detection of multiple offending vessels. Further studies are needed to understand regional differences in culprit vessel incidence and surgical outcomes in the Americas, Europe, and Asia.

Meningitis after elective intracranial surgery: a systematic review and meta-analysis of prevalence

Meningitis is a potential complication of elective intracranial surgery (EIS). The prevalence of meningitis after EIS varies greatly in the literature. The objective of this study was to estimate the overall pooled prevalence of meningitis following EIS. Four databases (PubMed, Scopus, Web of Science, and Embase) were searched to identify relevant studies. Meta-analyses of proportions were used to combine data. Cochran's Q and I2 statistics were used to assess and quantify heterogeneity. Additionally, several subgroup analyses were conducted to investigate the source of heterogeneity and examine differences in the prevalence based on variables such as geographical regions, income level, and meningitis type. The meta-analysis included 83 studies (30 959 patients) from 26 countries. The overall pooled prevalence of meningitis after EIS was 1.6% (95% CI 1.1-2.1), with high heterogeneity present (I2 = 88%). The pooled prevalence in low- to middle-income countries and high-income countries was 2.7% (95% CI 1.6-4.1) and 1.2% (95% CI 0.8-1.7), respectively. Studies that reported only aseptic meningitis had a pooled prevalence of 3.2% (95% CI 1.3-5.8). The pooled prevalence was 2.8% (95% CI 1.5-4.5) in studies that reported only bacterial meningitis. Similar prevalence rates of meningitis were observed in the subgroups of tumor resection, microvascular decompression, and aneurysm clipping. Meningitis is a rare but not exceptional complication following EIS, with an estimated prevalence of 1.6%.

[Quality of life in patients with hemifacial spasm after microvascular decompression and botulinum toxin therapy]

To date, microvascular decompression (MVD) and botulinum therapy (BT) confirm own efficacy in the treatment of hemifacial spasm (HFS). Quality of life (QOL) suffers first of all in these patients. Therefore, the dynamics of QOL indicators determines postoperative outcomes. Various researchers have proposed specialized scales for assessing QoL in HPS patients (HFS-7, HFS-8, HFS-30).

OBJECTIVE

To analyze QOL in patients with HPS before and after MVD and BT including HFS-7 score and regression of HFS.

MATERIAL AND METHODS

We analyzed data of patients (n=80) divided into two groups: group I - MVD of the facial nerve (n=66), group II - BT (n=14). Mean age of patients was 52.4 (range 28-76) and 58.1 years (range 23-73), respectively. QOL was assessed using a questionnaire enrolling clinical and anamnestic data, as well as HFS-7 scale. Clinical severity of HFS and effect on daily activity were assessed using the Tan scale. We analyzed the results of MVD and BT considering clinical improvement (regression of spasm) and HFS-7 score. A four-level gradation of clinical regression of spasm was used.

RESULTS

Patients with mild course of disease and higher QOL prefer BT. In our sample, 3 (21%) patients from the 2nd group preferred surgery a year after BT, and 13 (20%) patients from the 1st group had previously undergone BT in other hospitals. Changes in HFS-7 score before and after treatment were significant in both groups (p<0.005, t-test). Spearman's coefficient (R= -0.66) shows the correlation between clinical effect and HFS-7 score.

CONCLUSION

MVD and BT significantly improve QOL in patients suffering from HFS. Patients with less severe hemispasm prefer BT, but conversion to surgery is possible as disease progresses. Both treatment methods should be available for HFS patients. Treatment outcomes should be assessed using specialized scales designed for HFS.

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

Although microvascular decompression (MVD) is a reliable treatment for hemifacial spasm (HFS), postoperative delayed relief of persistent HFS is one of the main issues. In patients with hemifacial spasm, stimulation of a branch of the affected facial nerve elicits an abnormal response in the muscles innervated by another branch. Several specific types of waves were found in the abnormal muscle response (AMR). This study aimed to confirm the relationship between the initial morphology of the AMR wave and delayed relief of persistent HFS after MVD. We retrospectively analyzed and compared the data from 47 of 155 consecutive patients who underwent MVD for HFS at our hospital between January 2015 and March 2020. Based on the pattern of the initial AMR morphology on orbicularis oculi and mentalis muscle stimulation, patients were divided into two groups, namely, the monophasic and polyphasic groups. 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. There were significantly higher rates of persistent postoperative HFS in patients with the polyphasic type of initial AMR at 1 week and 1 month after the surgery (p < 0.05, respectively), as assessed using Yates chi-squared test and Fisher's exact test. A significant correlation was observed between delayed relief after MVD and polyphasic morphology of the AMR in electromyographic analysis in patients with hemifacial spasm.

Advances in Intraoperative Neurophysiology During Microvascular Decompression Surgery for Hemifacial Spasm

Microvascular decompression (MVD) is a widely used surgical intervention to relieve the abnormal compression of a facial nerve caused by an artery or vein that results in hemifacial spasm (HFS). Various intraoperative neurophysiologic monitoring (ION) and mapping methodologies have been used since the 1980s, including brainstem auditory evoked potentials, lateral-spread responses, Z-L responses, facial corticobulbar motor evoked potentials, and blink reflexes. These methods have been applied to detect neuronal damage, to optimize the successful decompression of a facial nerve, to predict clinical outcomes, and to identify changes in the excitability of a facial nerve and its nucleus during MVD. This has resulted in multiple studies continuously investigating the clinical application of ION during MVD in patients with HFS. In this study we aimed to review the specific advances in methodologies and clinical research related to ION techniques used in MVD surgery for HFS over the last decade. These advances have enabled clinicians to improve the efficacy and surgical outcomes of MVD, and they provide deeper insight into the pathophysiology of the disease.

Factors Related to the Delayed Cure of Hemifacial Spasm after Microvascular Decompression: An Analysis of 175 Consecutive Patients

Detailed studies assessing the factors related to delayed cure of hemifacial spasm (HFS) after microvascular decompression (MVD) are sparse. We aimed to evaluate the effect of 11 clinical factors on the time until the patient became spasm free after MVD. We enrolled 175 consecutive patients with HFS who underwent MVD between 2012 and 2018. The end point was defined as the time point at which the patient became spasm free based on the outpatient interview. Patients were divided into six groups depending on when they became spasm free after the operation, as follows: <7 days ( n  = 62), 7 days to 1 month ( n  = 28), 1 to 3 months ( n  = 38), 3 to 6 months ( n  = 25), 6 to 12 months ( n  = 17), and >12 months ( n  = 5). The median time to become spasm free after MVD was 30.0 days. Association of 11 factors (age, sex, laterality, number of offending arteries, vertebral artery compression, number of compression sites, compression at root detachment zone, preoperative Botox treatment, indentation of the brain stem on preoperative magnetic resonance image, transposition, and interposition) with spasm-free rate was assessed using the Cox's proportional hazards model. Spasm-free rate curve after MVD for the significant factor was obtained using the Kaplan-Meier method. In univariate and multivariate analyses, nontransposition was significantly related to delayed HFS cure after MVD (hazard ratio [HR], 0.60; 95% confidence interval [CI], 0.42, 0.87; p  = 0.0068 and HR, 0.60; CI, 0.43, 0.85; p  = 0.042, respectively). The spasm-free rate was higher in the transposition than in the nontransposition group ( p  = 0.0013). As shortening the time until spasm free after MVD improves patients' quality of life, transposition should be recommended. Prediction of spasm-free time could relieve the anxiety of postoperative patients.

Double collagen matrix grafting for dural closure in microvascular decompression: an alternative use of autologous fascial grafting

BACKGROUND

Watertight dural closure is a crucial step in preventing postoperative cerebrospinal fluid (CSF) leak and subsequent infection in posterior fossa surgery. The aim of this study is to assess an alternative use of collagen matrix double grafting in microvascular decompression (MVD).

METHODS

Dural closure using double collagen matrix grafts was retrospectively compared with autologous fascial grafting in 120 patients who underwent MVD. Double collagen matrix grafting technique, a combination use of inlay and onlay grafting (DuraGen^®, Integra Lifesciences, Plainsboro, NJ, USA, $700-800 for an MVD craniotomy size), was applied in 60 patients (the collagen matrix group). In the remaining 60 patients, an autologous fascial graft was sutured in a watertight fashion to the dural defect (the fascia group). Postoperative wound complications, such as CSF leak and infection, were retrospectively compared between the two groups.

RESULTS

CSF leaks were observed in 3 patients (5.0%) in the fascia group and in 2 patients (3.3%) in the collagen matrix group. All cases of CSF leakage presented with pseudomeningoceles except one patient who developed an incisional CSF leak. A repair surgery for CSF leak was required in this one patient in the fascia group. Subcutaneous abscesses were noted in 2 patients (3.3%) in the fascia group. There was no patient who developed a subcutaneous abscess in the collagen matrix group. One patient in each group developed aseptic meningitis. Statistical analyses revealed that the collagen matrix group showed non-inferior outcomes to the fascia group in CSF leaks and infectious complications.

CONCLUSIONS

Double grafting technique with a combination of inlay and onlay collagen sheets is a safe and secure alternative for watertight dural closure despite a cost limitation.

Sequential Change of Facial Nerve Motor Function after Microvascular Decompression for Hemifacial Spasm: An Electrophysiological Study

Hemifacial spasm (HFS) patients occasionally present with preoperative facial weakness (PFW) or develop delayed facial palsy (DFP) after microvascular decompression (MVD). This study is aimed to evaluate the neurophysiology underlying facial nerve motor dysfunction in HFS patients preoperatively and postoperatively. In all, 54 HFS patients without prior botulinum toxin injection who underwent MVD were retrospectively reviewed. The compound muscle action potential (CMAP) amplitude ratios of the affected and unaffected facial nerves, measured at 4 time points from preoperation to 1 year post-surgery, were aggregated. Clinical outcomes and the CMAP amplitude ratios were evaluated. Six patients (11.1%) presented with PFW, which correlated with advanced age (p = 0.007) and symptom duration (p = 0.001). The average duration to achieve PFW relief was 2.67 months postoperatively. The preoperative CMAP amplitude ratios of PFW patients were lower than those of patients without PFW (85.3% vs 95.7%). The ratios showed the lowest value at 1-week post-surgery in both groups (70.3% vs 90.9%), had a tendency toward improvement at 1 month, and finally recovered to almost the same level as that before the surgery at 1 year. Three patients (5.6%), whose CMAP ratios showed a persistent decrease from 1 week (56.5%) to 1 month (31%) after MVD, developed DFP. This study illustrates PFW in HFS patients reflects facial nerve axonal stress. MVD is effective in resolving spasm and PFW, without long-term damage to the facial nerve in most patients. In DFP patients, the direct and subsequent secondary axonal disorder develops on the postoperative facial nerve.

A prewarning sign for hearing loss by brainstem auditory evoked potentials during microvascular decompression surgery for hemifacial spasm

OBJECTIVE

We aimed to define the prewarning sign of brainstem auditory evoked potentials (BAEPs) associated with cerebellar retraction (CR) during microvascular decompression surgery for hemifacial spasm.

METHODS

A total of 241 patients with a latency prolongation of 1 ms or an amplitude decrement of 50% of wave V were analyzed. According to BAEPs before significant changes during CR, patients were classified into Groups A (latency prolongation of wave I [≥0.5 ms] without prolongation of the I-III interpeak interval [<0.5 ms]) and B (no latency prolongation of wave I [<0.5 ms] with prolongation of the I-III interpeak interval [≥0.5 ms]). BAEPs and postoperative hearing loss (HL) were compared between the two groups.

RESULTS

Group B comprised 160 (66.4%) patients. With maximal changes in wave V, latency prolongation (≥1 ms) with amplitude decrement (≥50%) was more common in Group B (p < 0.018). At the end of the operation, wave V loss was observed in 11 patients, including 10 patients from Group B. Five patients developed postoperative HL; all were from Group B.

CONCLUSIONS

Latency prolongation of wave III during CR was associated with serious BAEPs changes and postoperative HL.

SIGNIFICANCE

Latency prolongation of wave III is a significant prewarning sign.

Transposition of Vessels for Microvascular Decompression of Posterior Fossa Cranial Nerves: Review of Literature and Intraoperative Decision-Making Scheme

INTRODUCTION

Microvascular decompression with transposition of the involved vessels provides good surgical outcomes in cases of complex and recurrent neurovascular compression syndromes. We conducted a literature review to illustrate the variations in the surgical techniques used for transposition and to provide a practical decision-making scheme for transposition of the involved vessel.

METHODS

A PubMed Medline database record search was conducted using the following algorithm ("Microvascular Decompression Surgery"[Mesh]) OR (((Microvascular) OR (Macrovascular)) AND decompression AND surgery) AND (transposition). Only articles that detailed the intraoperative techniques were included.

RESULTS

A total of 48 articles were included. The adjacent anatomical walls to which the compressing vessel can be anchored were divided into 4 groups; A: roof (tentorium cerebelli), B: anterior wall (posterior surface of petrous bone and clivus), C: posterior wall (petrosal surface of the cerebellum), and D: "no wall" required. A new decision-making scheme based on the following 2 questions was designed: 1) is the conflicting vessel amenable to transposition to a nearby wall in the cerebello-brainstem space? 2) what is the closest wall to secure the transposed vessel?

CONCLUSIONS

Transposition of the involved vessel is a valuable procedure for microvascular decompression of the posterior fossa cranial nerves. Anchoring the vessel to the adjacent anatomical wall ensures secure transposition. The proposed algorithm provides a systemic scheme to identify the optimal anatomical wall, and to determine the technique and material that can be used to anchor involved vessel. This scheme is an efficient method to inform the intraoperative decision-making process.

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 efficacy of temporary clamping of V3 with a suboccipital far-lateral approach in microvascular decompression for Hemifacial spasm associated with the vertebral artery

Hemifacial spasm (HFS) is often caused by compression of the vertebral artery (VA) directly or indirectly as a result of other intervening vessels, so VA-associated HFS is difficult to treat. Recently, we have achieved good surgical outcomes using a far lateral approach and temporary clamping of V3 for VA-associated HFS. Herein, we present our method with an accompanying surgical video. From April 2018 to March 2019, 5 patients with VA-associated HFS underwent surgery, and pre-and postoperative symptoms and postoperative complications were evaluated. In the procedure, the suboccipital muscles were dissected and reflected layer by layer, and the extracranial VA (V3) was secured within the suboccipital triangle. A lateral suboccipital craniotomy followed by far lateral drilling was made to widen the surgical field from the caudolateral side. After reducing the VA flow pressure by temporary clamping of V3, the VA was transposed using a Teflon sling via two triangular space above and below the lower cranial nerves (LCNs). Causative vessels included direct VA compression in two cases and intervening vessels in three cases. The symptoms disappeared in four cases and improved satisfactorily in one case. One patient had mild hearing loss (approximately 10 dB) and hoarseness, but both improved 9 months after surgery. There was no postoperative cerebrospinal fluid leakage in any cases. A wide surgical field via the far lateral approach and the temporary clamping of V3 contributed to thorough observation of the REZ and safe and complete VA transposition.

Endoscope Assisted Microvascular Decompression: Are the Advantages Still Worthy Towards More?

Background

Microvascular decompression is the definitive treatment of various neuralgias affecting cranial nerves. The compression on a cranial nerve could be at the root entry zone, especially the trigeminal nerve. Endoscope-assisted microsurgery may help avoid missing a hidden vascular structure.

Study design

Retrospective clinical case series.

Patient and methods

Twenty-five patients with facial pain and five patients with hemifacial spasm constituted this study. FIESTA MRI was the pre-operative neuroimaging modality. Retrosegmoid craniectomy was done for all patients. Microscope was initially used for exploration and arachnoid dissection around the nerve. The endoscope was applied thereafter for exploration and confirmation of the proper insertion of the Teflon.

Results

Using the endoscope, cerebellar retraction was reduced by 0.5 to 0.8 cm in 90% of patients. Root entry zone and entry of the nerve through the corresponding skull base foramen was clearly visualized by the endoscope. Endoscope enabled a wider area of exploration and panoramic view, which could not be obtained by the microscope. Patients with trigeminal neuralgia had a median pre-operative VAS of 9, while it was only 1 in early post-operative and 0 in 6-month post-operatively. Patients with HFS were completely recovered.

Conclusion

The advantages of microvascular decompression are still worthy. Complications are minimal, and the view is much more panoramic. The different viewing angles and ability to directly reach corners is an absolute endoscopic advantage. Therefore, avoidance of missing vascular structures and incomplete recovery can be assured.

Arachnoid bands and venous compression as rare causes of hemifacial spasm: analysis of etiology in 353 patients

BACKGROUND

Hemifacial spasm is usually caused by arterial compression at the root exit zone of the facial nerve. However, other etiologies have been reported. The aim of this study was to analyze the frequency of other causes of hemifacial spasm.

METHODS

Our prospectively maintained hemifacial spasm database containing all patients who underwent microvascular decompression (MVD) for hemifacial spasm from 2002 to 2018 was reviewed. All offending structures were identified and recorded by the surgeon at the time of surgery. Additionally, the operative videos were analyzed retrospectively.

RESULTS

MVD was performed in 353 patients. Arterial compression was the main cause of hemifacial spasm in 341 (96.9%) patients. Combined venous-arterial compression was seen in 7 (2.0%) patients. In one patient, the compression was from a large vein. In two patients, no compression was found. One patient who suffered from Bell's palsy many years previously had severe synkinesis and the other had facial tics. In two patients, the spasm was caused due to strangulation of the facial nerve by arachnoid bands. Long-term follow-up of more than 18 months was available in 249 patients with total resolution or near total resolution of spasms in 89.96% of patients.

CONCLUSIONS

In most patients with hemifacial spasm, arterial vessels are involved in compressing the facial nerve. Purely venous compression is rarely encountered. We report for the very first time arachnoid bands strangulating the nerve as a cause for hemifacial spasm without involvement of any vessel.

Preoperative risk assessment for predicting the opening of mastoid air cells in lateral suboccipital craniotomy for microvascular decompression

OBJECTIVE

Opening of mastoid air cells (MACs), a complication of lateral suboccipital craniotomy for microvascular decompression (MVD), might cause cerebrospinal fluid (CSF) leakage and meningitis. Only a few studies have investigated the association of degree of MAC development and actual opening of MACs. The present study focused on preoperative risk assessment for predicting the opening of MACs.

PATIENTS AND METHODS

The study included 204 consecutive patients who underwent MVD at our hospital between January 2014 and December 2018. We retrospectively collected clinical and neuroimaging data from electronic medical charts and discharge summaries. MACs were classified into four types according to neuroimaging data. Postoperative computed tomography (CT) was used to assess patients with and without CSF leakage into MACs.

RESULTS

No CSF leakage was observed into types 1 and 2 MACs, but it was noted in 14 of 46 patients (30 %) with type 3 and 44 of 58 patients (76 %) with type 4 MACs. Opening of MACs during surgery could not be recognized in 33 (57 %). CSF rhinorrhea was noted in 1 of the 58 patients with CSF leakage into MACs and meningitis was not noted.

CONCLUSION

Patients with types 3 and 4 MACs have a high risk of CSF leakage. Complete prevention of mild symptoms, such as ear obstruction, is challenging even if opened MACs are sealed, but serious complications, such as CSF rhinorrhea and meningitis, can be avoided. For cases in which preoperative CT reveals a high risk of opening of MACs, preventive closure should be performed.

Facial motor evoked potential with paired transcranial magnetic stimulation: prognostic value following microvascular decompression for hemifacial spasm

OBJECTIVE

Microvascular decompression (MVD) is widely considered the treatment of choice for hemifacial spasm (HFS), but not all patients immediately benefit from it. Numerous electrophysiological tests have been employed to monitor the integrity of the facial nerve prior to, during, and after MVD treatment. The authors sought to verify if facial motor evoked potential (FMEP) with paired transcranial magnetic stimulation (pTMS) can be utilized as a tool to predict prognosis following MVD for HFS.

METHODS

FMEP using pTMS was performed preoperatively and postoperatively for 527 HFS patients who underwent an MVD treatment. Various interstimuli intervals (ISIs), which included 2, 10, 20, 25, 30, 75, and 100 msec, were applied for each paired stimulation and pTMS(%) was obtained. A graph of pTMS(%) versus each ISI was drawn for every patient and its pattern was analyzed in accordance with patients' clinical outcomes.

RESULTS

With ISIs of 75 and 100 msec, pTMS(%) was physiologically further inhibited, whereas it was relatively facilitated under ISIs of 20, 25, and 30 msec; loss of this specific pattern, that is, further inhibition-relative facilitation, indicated impaired integrity of the facial nerve. Those patients who immediately benefited from an MVD and experienced no relapse tended to show proper restoration of this further inhibition-relative facilitation pattern (p = 0.01). Greater resemblance between the physiological pattern of pTMS(%) and postoperative pTMS(%) was correlated to better outcome (p = 0.019).

CONCLUSIONS

A simple linear graph of pTMS(%) versus each ISI may be a helpful tool to predict prognosis for HFS following an MVD.

Different Roles of Microvascular Decompression in Hemifacial Spasm and Trigeminal Neuralgia

Objectives  Microvascular decompression (MVD) involves the same procedure for both hemifacial spasm (HFS) and trigeminal neuralgia (TN), the resulting clinical courses are different. The aim of this study was to compare differences in MVD operations for HFS and TN and to determine the consequences of these differences on the clinical courses of the two diseases. Methods  The medical records of patients who underwent an MVD operation between January 1998 and March 2013 were reviewed. Results  A total of 2,263 patients were enrolled, 222 had TN and 2,040 had HFS. In the HFS group, the estimated cure rates at postoperative years 1, 2, and 3 were 92.0, 93.4, and 93.6%. In the TN group, the estimated cure rates at postoperative years 1, 2, and 3 were 88.4, 89.4, and 91.4%. Comparison of the initial treatment response between the HFS and TN groups did not reveal any statistically significant difference ( p  = 0.338). Among the 1,749 HFS patients initially cured by MVD, 57 were worsened. Among the 181 TN patients treated by MVD, 43 were worsened, with ≥ BNI III (Barrow Neurological Institute pain intensity score III) 12 worsened to a BNI score of IV. Comparing the recurrence rate between the HFS and TN groups, there was a statistically significant difference for cases with ≥ BNI III ( p  < 0.001), but not in cases with ≥ BNI IV ( p  = 0.498). Conclusion  MVD is a promising treatment for HFS. In contrast, MVD-treated TN had a risk of recurrence. The MVD operation should be carefully considered when applied as a treatment for TN patients.

Delayed Facial Palsy after Microvascular Decompression: Report of Two Cases

Microvascular decompression (MVD) is a novel surgical procedure predominantly performed for treating trigeminal neuralgia (TN) and hemifacial spasm (HS). Multiple studies have proven the long-term success of MVD for both these conditions. The most common complications of MVD reported include chemical meningitis, facial hypesthesia, cerebrospinal fluid leak, facial paresis, and hearing loss. Delayed facial palsy (DFP) is an uncommon complication mostly noted in MVD for HS and after the removal of acoustic tumors. We report two cases of DFP occurring after performing MVD, one each for HS and TN. This is also the first case of DFP to be reported after MVD for TN. Both were young females who developed DFP 2 weeks after surgery. They were managed with oral steroids and acyclovir for 2–3 weeks and achieved excellent outcome at an average of 4.5 weeks from the onset. We conclude that although majority of the cases improve spontaneously, steroids and acyclovir might assist in faster recovery.

Delayed Facial Palsy After Microvascular Decompression for Hemifacial Spasm

OBJECTIVE

We explored the risk factors for the occurrence of delayed facial paralysis (DFP) after microvascular decompression (MVD) for hemifacial spasm (HFS).

METHODS

A retrospective study was conducted of 636 patients who had undergone MVD for HFS by the same neurosurgery department of China-Japan Friendship Hospital from January 2006 to May 2016. Of the 636 patients, 50 (7.9%) had presented with DFP, which had developed from 2 to 60 days postoperatively (average, 12.9 ± 10.0005 days). All 50 patients with DFP had recovered completely within 10-300 days (average, 88.7 ± 61.389 days) after the onset of DFP. We randomly selected 100 patients from the 586 patients without DFP as the control group. Univariate and multivariate logistic analyses were used to analyze the risk factors involved in the occurrence of DFP.

RESULTS

Univariate analysis showed that the disease course was the only factor associated with the development of DFP (P = 0.003). Furthermore, on multivariate logistic analysis, the course of HFS was the only risk factor associated with the development of DFP (P = 0.01). Additionally, the Spearman test revealed a positive correlation between the onset of DFP and the duration of the DFP symptoms (r_s = 0.682; P < 0.001).

CONCLUSION

Although DFP frequently occurred after MVD, it can recover spontaneously. The longer the course of HFS, the more frequently DFP will occur after MVD. The earlier that DFP develops, the shorter will be the time to recovery.

Intraoperative Neurophysiological Monitoring during Microvascular Decompression Surgery for Hemifacial Spasm

Hemifacial spasm (HFS) is due to the vascular compression of the facial nerve at its root exit zone (REZ). Microvascular decompression (MVD) of the facial nerve near the REZ is an effective treatment for HFS. In MVD for HFS, intraoperative neurophysiological monitoring (INM) has two purposes. The first purpose is to prevent injury to neural structures such as the vestibulocochlear nerve and facial nerve during MVD surgery, which is possible through INM of brainstem auditory evoked potential and facial nerve electromyography (EMG). The second purpose is the unique feature of MVD for HFS, which is to assess and optimize the effectiveness of the vascular decompression. The purpose is achieved mainly through monitoring of abnormal facial nerve EMG that is called as lateral spread response (LSR) and is also partially possible through Z-L response, facial F-wave, and facial motor evoked potentials. Based on the information regarding INM mentioned above, MVD for HFS can be considered as a more safe and effective treatment.

Combined Hyperactive Dysfunction Syndrome of the Cranial Nerves: Analysis of 37 Cases and Literature Review

BACKGROUND

Hyperactive dysfunction syndrome (HDS) of the cranial nerves, such as trigeminal neuralgia (TN), hemifacial spasm (HFS), and glossopharyngeal neuralgia (GPN), is commonly managed by microsurgical treatment. However, certain patients may present a combination of these syndromes in the neurosurgery department. Here, we aimed to retrospectively assess patients with combined HDS from a single center.

METHOD

Of 1275 consecutive patients with HDS treated at our center between 2007 and 2017, 37 patients with combined HDS were enrolled, and their medical and surgical records were analyzed.

RESULTS

The patients with combined HDS, accounting for 2.9% of all patients with HDS, included 22 patients with bilateral TN, 5 patients with TN-HFS, 8 patients with TN-GPN, and 2 patients with GPN-HFS. A comparison of patients with single and combined HDS indicated a significant difference in the mean age at initial diagnosis (63.57 vs. 56.18 years, P = 0.000) but no such difference in the sex ratio (0.54 vs. 0.59, P = 0.865) or incidence of hypertension (32.43% vs. 24.56%, P = 0.274). In total, 32 microvascular decompression (MVD) procedures were performed in the 27 patients with combined HDS, and repeated MVD was required in 5 patients with bilateral TN. Of the 27 patients who underwent MVD, 25 (92.6%) experienced clinical cure or obvious alleviation.

CONCLUSIONS

Combined HDS involves a group of functional disturbance disorders affecting specific cranial nerves, and it may include TN, HFS, and GPN. In addition to gender and incidence of hypertension, age appeared to be a vital indicator for the development of combined HDS, although this finding was inconsistent in previous studies. MVD appears to be a safe and effective treatment for combined HDS, with a high rate of long-term success.

Delayed hearing loss after microvascular decompression for hemifacial spasm

BACKGROUND

This study aimed to analyze cases of delayed hearing loss after microvascular decompression (MVD) for hemifacial spasm and identify the characteristic features of these patients.

METHODS

We retrospectively reviewed the medical records of 3462 patients who underwent MVD for hemifacial spasm between January 1998 and August 2017.

RESULTS

Among these, there were 5 cases in which hearing was normal immediately postoperatively but delayed hearing loss occurred. None of the 5 patients reported any hearing disturbance immediately after the operation. However, they developed hearing problems suddenly after some time (median, 22 days; range 10-45 days). On examination, sensorineural hearing loss was confirmed. High-dose corticosteroid treatment was prescribed. Preoperative hearing levels were restored after several months (median duration from the time of the operation, 45 days; range 22-118 days). Interestingly, the inter-peak latency of waves I-III in the brainstem auditory evoked potential (BAEP) was prolonged during the surgery, but recovered within a short time.

CONCLUSION

Delayed hearing loss may occur after MVD for HFS. Prolongation of the inter-peak latency of waves I-III seems to be associated with the occurrence of delayed hearing loss. It is possible that BAEP changes may predict delayed hearing loss, but confirmatory evidence is not available as yet. Analysis of more cases is necessary to determine the utility of BAEP monitoring to predict delayed hearing loss after MVD and to identify its exact cause.

Endoscope-Assisted Microneurosurgery for Neurovascular Compression Syndromes: Basic Principles, Methodology, and Technical Notes

Background:

Microscopic microvascular decompression (MVD) has a low but not negligible failure rate due to some missed conflicts, especially in case of multiple offending vessels. The reported study is aimed to assess the principles, methodology, technical notes, and effectiveness of the endoscope-assisted (EA) MVD for neurovascular compression syndromes (NVCS) in the posterior fossa.

Materials and Methods:

A series of 43 patients suffering from an NVCS and undergone to an EA MVD were retrospectively reviewed. Syndromes were trigeminal neuralgia in 25 cases, hemifacial spasm in nine cases, positional vertigo in six cases, glossopharyngeal neuralgia in two cases, and spasmodic torticollis in one case. In all cases, a 0°–30° specially designed endoscope was inserted into the surgical field to find/treat those conflicts missed by the microscopic exploration. Each procedure was judged in terms of the effectiveness of the adjunct of the endoscope according to a three types classification system: Type I – improvement in the visualization of the nerve's root entry/exit zone; Type II – endoscopic detection of one or more conflicts involving the ventral aspects of the nerve and missed by the microscope; Type III – endoscope-controlled release of the neurovascular conflict otherwise difficult to treat under the only microscopic view.

Results:

A total of 55 conflicts were found and treated. Twenty-eight procedures were classified as Type I, nine as Type II, and six as Type III. All the patients had a full recovery from their symptoms.

Conclusions:

In selected cases, EA MVD offers some advantages in the detection and treatment of neurovascular conflicts in the posterior fossa.

Hemifacial Spasm Caused by Vascular Compression in the Cisternal Portion of the Facial Nerve: Report of Two Cases with Review of the Literature

Although primary hemifacial spasm (HFS) is mostly related to a vascular compression of the facial nerve at its root exit zone (REZ), its occurrence in association with distal, cisternal portion has been repeatedly reported during the last two decades. We report two patients with typical HFS caused by distal neurovascular compression, in which the spasm was successfully treated with microvascular decompression (MVD). Vascular compression of distal, cisternal portion of the facial nerve was identified preoperatively in the magnetic resonance imaging (MRI). It was confirmed again with intraoperative findings of compression of cisternal portion of the facial nerve by the meatal loop of the anterior inferior cerebellar artery (AICA) and absence of any offending vessel in the REZ of the facial nerve. Immediate disappearance of lateral spread response (LSR) after decompression and resolution of spasm after the operation again validated that HFS in the current patients originated from the vascular compression of distal, cisternal portion of the facial nerves. According to our literature review of 64 patients with HFS caused by distal neurovascular compression, distal compression can be classified by pure distal neurovascular compression (31 cases, 48.4%) and double compression (both distal segment and the REZ of the facial nerves, 33 cases [51.6%]) according to the presence or absence of simultaneous offender in the REZ. Eighty-four percent of 64 identified distal offenders were the AICA, especially its meatal and postmeatal segments. Before awareness of distal neurovascular compression causing HFS and sophisticated MRI imaging (before 2000), the rate of reoperation was high (58%). Preoperative MRI and intraoperative monitoring of LSR seems to be an essential element in determination of real offending vessel in MVD caused by distal offender.

Microvascular Decompression in Patients Aged 30 Years or Younger

Objective:

The aim of this study was to identify the etiology of hemifacial spasm (HFS) and trigeminal neuralgia (TN) in patients aged 30 years or younger and to examine the efficacy of microvascular decompression (MVD).

Patients and Methods:

Between 1996 and 2012, 228 HFS and 190 TN patients underwent MVD at Atsuchi Neurosurgical Hospital. Of these, 7 patients were 30 years of age or younger at the time of treatment (HFS: n = 6, TN: n = 1). Assessments were based on their medical history and on magnetic resonance imaging, magnetic resonance angiography, surgical, and follow-up findings.

Results:

The age of the 6 HFS patients ranged from 23 to 30 years (mean 27.8 ± 1.8 [standard deviation] years) at the time of surgery; the earliest symptom onset was in an 11-year-old boy. We noted vascular variations in 5 patients, a duplicate posterior inferior cerebellar artery in 2 patients, a short basilar artery in 1 patient, and an aberrant arterial course in 2 patients. At the latest follow-up, 1–69 months after MVD, 5 of the HFS patients were asymptomatic and the 6^th had mild residual symptoms. A 23-year-old TN female underwent straightening of the trigeminal nerve by separation of a thickened arachnoid membrane from the nerve and dislocation of a small branch of the superior cerebellar artery from the distal end of the root exit zone. While she continued to experience occasional facial pain 48 months after the operation, she required no medication because surgery yielded significant pain amelioration.

Conclusion:

Although the pathogenesis of early-onset HFS and TN remains unclear, our findings suggest that vascular variations may be related to the etiology of vascular compression symptoms in patients with HFS or TN. MVD was useful for the treatment of neurovascular compression symptoms in young patients.

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

Background

Hemifacial spasm (HFS) is a benign disease caused by the hyper excitement of facial nerves owing to vessel compression. The offending vessels are usually arteries, such as anterior and posterior inferior cerebellar or vertebral arteries, but there are few reports of vein involvement cases.

Objective

The aim of this study was to investigate veins as offending vessels in patients with HFS confirmed by abnormal muscle response (AMR).

Methods

We analyzed 5 patients with HFS caused by veins among 78 patients with HFS over the past 10 years. All patients underwent microvascular decompression (MVD) with AMR monitoring, whereas 3 of them underwent a second MVD. The mean follow-up time was 97 months.

Results

Arteries were thoroughly decompressed in 3 patients with a failed first MVD surgery who received a second surgery, during which veins at the root exit point (RExP) were decompressed with the disappearance or a significant decrease in the amplitude of AMR. Two patients showed spasm resolution after the first surgery when veins were decompressed together with the disappearance of AMR. The location of veins was RExP and the cisternal portion. All patients had excellent outcomes within 3 months, and no complications were observed.

Conclusions

Veins can be offending vessels in HFS patients. AMR is useful to determine the endpoint in these cases. Once arteries are decompressed thoroughly with residual AMR, surrounding veins at unusual sites, such as the RExP or the cisternal portion, must be checked to prevent persistent HFS. Complete decompression of veins leads to a good clinical outcome.

Endovascular Flow Diversion for Hemifacial Spasm Induced by a Vertebral Artery Aneurysm: First Experience

BACKGROUND AND IMPORTANCE

Flow diversion for the treatment of aneurysm-induced hemifacial spasm (HFS) has not been previously described.

CLINICAL PRESENTATION

The authors present the case of a 60-yr-old woman who presented with 1 yr of progressive left HFS secondary to a vertebral artery aneurysm compressing the root entry zone of cranial nerve VII. The patient's aneurysm was successfully treated with a flow diverting stent.

CONCLUSION

In the immediate postoperative period, the patient had near complete resolution of her HFS symptoms. At her 6-mo follow-up the patient had no angiographic filling of the aneurysm and her HFS symptoms had completely resolved.

Hemifacial Spasm Caused by a Vein: A Case Report

Hemifacial spasm (HFS) caused by a venous offender is rare, and its clinical course and optimal surgical strategy are unclear. A case of 57-year-old male who had an HFS caused by a venous offender is described in this report. Frontalis, orbicularis oculi, orbicularis oris, and mentalis muscles were involved while his platysma muscle showed no spasm. He was treated successfully with microvascular decompression using Teflon felt and 12 months outcome was excellent without any complications. Lateral spread response was not observed in the facial electromyography during the whole operation. Adequate visualization of the facial nerve root exit zone and meticulous exploration for offenders are necessary to avoid surgical failure and reoperation.

Veins of the Cerebellopontine Angle and Specific Complications of Sacrifice, with Special Emphasis on Microvascular Decompression Surgery. A Review

Good knowledge of the anatomy of veins is of crucial importance for the functional surgery of cranial nerve (CN) disorders, especially microvascular decompression for trigeminal neuralgia (TN), hemifacial spasm (HFS), and vagoglossopharyngeal neuralgia (VGPN). Although controversial, veins may be involved in neurovascular conflicts and may constitute dangerous obstacles to access to the CNs. With the aim of estimating the implications of veins in those diseases and evaluating the linked surgical difficulties, we carried out a review of the literature from 2000 to the end of February 2018. For this review, articles found on PubMed that gave enough precision about veins were retained (39 articles on TN, 38 on HFS, 8 on VGPN, and 26 on complications related to venous sacrifices). Before this review, we described a simplified anatomic classification of veins, amenable to easing the surgical approach to CNs. Access to the trigeminal nerve, via the infratentorial-supracerebellar route, is almost always affected by the superficial superior petrosal venous system, whereas access to the facial and cochleovestibular complex as well as to the lower CNs, through the infrafloccular trajectory, is almost always exempt of important venous obstacles. Respective incidences of venous compression at the origin of hyperactive CN syndromes are given. The percentages of a venous conflict alone were calculated at 10.8% for TN, 0.1% for HFS, and 2.9% for VGPN. We review the complications considered in relation with venous sacrifices. Precautions to minimize these complications are given.

A New Score to Predict the Risk of Hearing Impairment After Microvascular Decompression for Hemifacial Spasm

BACKGROUND

Intraoperative monitoring of brainstem auditory evoked potentials (BAEPs) has been implemented to reduce the risk of hearing impairment during microvascular decompression for hemifacial spasm.

OBJECTIVE

To evaluate intraoperative monitoring of BAEPs during microvascular decompression in patients with hemifacial spasm for predicting the risk of hearing impairment after surgery.

METHODS

This prospective study included 100 patients. BAEPs were recorded for all patients. We established a scoring system for the changes in wave I amplitude, I-III interpeak latency, and wave V amplitude and latency. For each change, total points were calculated, and a score out of 6 was assigned to every patient. We classified the patients based on the points scored into 3 risk groups: low-risk (0-3), medium-risk (4-5), and high-risk (6). Further, the correlation between the score and the hearing outcome was evaluated to detect the incidence and degree of hearing impairment.

RESULTS

Eighty-seven patients scored 0 to 3, 10 scored 4 to 5, and 3 scored 6. The degree of hearing impairment was proportionate to the score recorded at the end of surgery, and patients in the low-risk group showed no impairment; medium-risk group, deterioration of maximum 2 grades according to World Health Organization classification of hearing impairment; and high-risk group, deterioration of 3 to 4 grades.

CONCLUSION

Intraoperative monitoring of BAEPs evaluated through our scoring system was valuable in predicting hearing impairment after surgery.

Microvascular Decompression for Patients With Hemifacial Spasm Associated With Common Trunk Anomaly of the Cerebellar Arteries-Case Study and Review of Literature

BACKGROUND

Few previous studies have described the origin of both anterior and posterior inferior cerebellar arteries from one vessel as a common trunk anomaly. No previous studies have clearly described the aforementioned anomaly depending on intraoperative endoscopic visualization.

OBJECTIVE

To evaluate the association of a common trunk anomaly with hemifacial spasm, which makes microvascular decompression more challenging.

METHODS

All patients with common trunk anomaly associated with hemifacial spasm who received surgical treatment between 2006 and 2015 in our institution were identified in our prospectively collected database. Detection of the common trunk anomaly was performed using the intraoperative high-definition endoscopic inspection and confirmed by a retrospective review of the obtained operative videos.

RESULTS

Out of 248 cases of hemifacial spasm, 21 cases with a common trunk anomaly were detected, with an incidence rate of 8.5%. In 6 cases, the spasm was caused by more than 1 offending vessel "complex compression." In 19 cases, total recovery occurred on follow-up, while in 1 case, 90% recovery occurred. One patient was spasm-free immediately after surgery, but died 3 wk after operation from herpes encephalitis.

CONCLUSION

Common trunk anomaly in hemifacial spasm is rare. The surgical technique is mostly identical to decompression with normally arising vessels. However, in case of a bifurcation situated close to the compression site where the offending vessel cannot be transposed freely, an extensive cushioning along the trunk and the offending vessels with teflon pledgets should be performed. The presence of a common trunk anomaly does not affect the surgical results.

Quantitative study of the correlation between cerebellar retraction factors and hearing loss following microvascular decompression for hemifacial spasm

BACKGROUND

This prospective study quantitatively measured the cerebellar retraction factors, including retraction distance, depth and duration, and evaluated their potential relationship to the development of hearing loss after microvascular decompression (MVD) for hemifacial spasm (HFS).

METHODS

One hundred ten patients with primary HFS who underwent MVD in our department were included into this study. The cerebellar retraction factors were quantitatively measured on preoperative MR and timed during MVD. Associations of cerebellar retraction and other factors to postoperative hearing loss were analyzed.

RESULTS

Eleven (10%) patients developed hearing loss after MVD. Compared with the group without hearing loss, the cerebellar retraction distance, depth and duration of the group with hearing loss were significantly greater (p < 0.05). Multivariate regression analysis showed that greater cerebellar retraction depth and longer retraction duration were significantly associated with a higher incidence of postoperative hearing impairment (p < 0.05).

CONCLUSION

This study strongly suggested a correlation between the cerebellar retraction factors, especially retraction depth and duration, and possibility of hearing loss following MVD for HFS.

Hearing Loss following Posterior Fossa Microvascular Decompression: A Systematic Review

Objectives (1) Determine the prevalence of hearing loss following microvascular decompression (MVD) for trigeminal neuralgia (TN) and hemifacial spasm (HFS). (2) Demonstrate factors that affect postoperative hearing outcomes after MVD. Data Sources PubMed-NCBI, Scopus, CINAHL, and PsycINFO databases from 1981 to 2016. Review Methods Systematic review of prospective cohort studies and retrospective reviews in which any type of hearing loss was recorded after MVD for TN or HFS. Three researchers extracted data regarding operative indications, procedures performed, and diagnostic tests employed. Discrepancies were resolved by mutual consensus. Results Sixty-nine references with 18,233 operations met inclusion criteria. There were 7093 patients treated for TN and 11,140 for HFS. The overall reported prevalence of hearing loss after MVD for TN and HFS was 5.58% and 8.25%, respectively. However, many of these studies relied on subjective measures of reporting hearing loss. In 23 studies with consistent perioperative audiograms, prevalence of hearing loss was 13.47% for TN and 13.39% for HFS, with no significant difference between indications ( P = .95). Studies using intraoperative brainstem auditory evoked potential monitoring were more likely to report hearing loss for TN (relative risk [RR], 2.28; P < .001) but not with HFS (RR, 0.88; P = .056). Conclusion Conductive and sensorineural hearing loss are important complications following posterior fossa MVD. Many studies have reported on hearing loss using either subjective measures and/or inconsistent audiometric testing. Routine perioperative audiogram protocols improve the detection of hearing loss and may more accurately represent the true risk of hearing loss after MVD for TN and HFS.

Long-Term Outcome of Repeat Microvascular Decompression for Hemifacial Spasm

OBJECTIVE

Although repeat microvascular decompression (MVD) for hemifacial spasm (HFS) in patients with failed prior MVD is potentially curative, little is known about the long-term results of repeat MVD. We aimed to evaluate the long-term outcomes and complications after repeat MVD for HFS.

METHODS

We performed repeat MVD on 78 consecutive patients who had undergone a prior MVD >1 year previously. Follow-up data were available for 58 patients, with a median follow-up period of 8.6 years (range, 6.9-10.2 years). The patients were assessed for intraoperative findings, relief results, and complications at discharge and at follow-up, as well as the associations between the preoperative characteristics and outcomes.

RESULTS

At discharge, of 78 patients with repeat MVD, 72 (92.3%) achieved complete spasm resolution and 1 (2.6%) had significantly improved spasm resolution. Of all patients, 9% (7 of 78) presented short-term complications, including partial hearing loss, hemifacial paresis, and cerebrospinal fluid leak. At follow-up, 45 of 58 (77.6%) patients had complete relief and 10 of 58 (17.2%) had improved relief. Permanent complications occurred in 14 patients (24.1%), with partial hearing loss and mild hemifacial paresis being the most common. Despite the complications, 51 of 58 patients (91.4%) reported an excellent life quality. No significant correlation was found between preoperative characteristics, such as age, interval to prior MVD, or interval to recurrence, and outcomes including short-term or long-term relief results and complications.

CONCLUSIONS

Repeat MVD provides lasting relief for most patients with persistent or recurrent HFS, albeit with a relatively high complication rate.

Tenth case of bilateral hemifacial spasm treated by microvascular decompression: Review of the pathophysiology

BACKGROUND

Bilateral hemifacial spasm (BHFS) is a rare neurological syndrome whose diagnosis depends on excluding other facial dyskinesias. We present a case of BHFS along with a literature review.

METHODS

A 64-year-old white, hypertense male reported involuntary left hemiface contractions in 2001 (aged 50). In 2007, right hemifacial symptoms appeared, without spasm remission during sleep. Botulinum toxin type A application produced partial temporary improvement. Left microvascular decompression (MVD) was performed in August 2013, followed by right MVD in May 2014, with excellent results. Follow-up in March 2016 showed complete cessation of spasms without medication.

RESULTS

The literature confirms nine BHFS cases bilaterally treated by MVD, a definitive surgical option with minimal complications. Regarding HFS pathophysiology, ectopic firing and ephaptic transmissions originate in the root exit zone (REZ) of the facial nerve, due to neurovascular compression (NVC), orthodromically stimulate facial muscles and antidromically stimulate the facial nerve nucleus; this hyperexcitation continuously stimulates the facial muscles. These activated muscles can trigger somatosensory afferent skin nerve impulses and neuromuscular spindles from the trigeminal nerve, which, after transiting the Gasser ganglion and trigeminal nucleus, reach the somatosensory medial posterior ventral nucleus of the contralateral thalamus as well as the somatosensory cortical area of the face. Once activated, this area can stimulate the motor and supplementary motor areas (extrapyramidal and basal ganglia system), activating the motoneurons of the facial nerve nucleus and peripherally stimulating the facial muscles.

CONCLUSIONS

We believe that bilateral MVD is the best approach in cases of BHFS.