Comparison of transposition and interposition methods in microvascular decompression for hemifacial spasm: an analysis of 109 cases performed by a single surgeon in a single-center retrospective study.

BACKGROUND: Microvascular decompression (MVD), the standard surgical approach for hemifacial spasm (HFS), can be divided into the interposition and transposition methods. Although the risk of HFS recurrence following interposition has been reported, there is limited data comparing long-term outcomes between both methods performed by a single surgeon. This study aimed to investigate the efficacy of MVD techniques on HFS by comparing surgical outcomes performed by a single surgeon in a single-center setting. METHODS: A total of 109 patients who underwent MVD were analyzed and divided into the transposition (86 patients) and interposition (23 patients) groups. Postoperative outcomes at 1 month and 1 year were assessed and compared, including rates of spasm relief, complications, and recurrence. RESULTS: Outcome assessment revealed higher rates of early spasm relief in the interposition group (66.3% vs. 100%, transposition vs. interposition, respectively, p = 0.0004), although spasm relief at 1-year postoperatively was comparable between the two groups (84.9% vs. 95.7%, transposition vs. interposition, respectively, p = 0.2929). No significant differences were observed in complication and recurrence rates. Kaplan-Meier analysis demonstrated no significant differences in the duration of spasm resolution by MVD method (p = 0.4347, log-rank test). CONCLUSION: This study shows that both the transposition (Surgicel® and fibrin glue) and interposition (sponge) methods were excellent surgical techniques. The interposition method may achieve earlier spasm resolution compared to the transposition method.

Tinnitus: an underreported condition following microvascular decompression for hemifacial spasm.

PURPOSE: While hearing loss is a well-known condition following microvascular decompression (MVD) for hemifacial spasm (HFS), tinnitus is an underreported one. This study aims to identify prevalence, characteristics, severity, and predictors of tinnitus following MVD for HFS. METHODS: A single-center cohort of 55 HFS patients completed a questionnaire approximately 5 years following MVD. Data encompassed tinnitus presence, side, type, onset, and severity measured by a 10-point Visual Analogue Scale (VAS). Descriptive, correlation, and logistic regression analyses were conducted. RESULTS  : At surgery, participants' median age was 58 years (IQR 52-65). The median duration of HFS symptoms before surgery was 5 years (IQR 3-8), slightly predominant on the left (60%). Postoperative tinnitus was reported by 20 patients (36%), versus nine (16%) that reported preoperative tinnitus. Postoperative tinnitus was ipsilateral on the surgical side in 13 patients (65%), bilateral in six (30%), and contralateral in one (5%). Among patients with bilateral postoperative tinnitus, 33% did not have this preoperatively. Tinnitus was continuous in 70% of cases and pulsatile in 30%. Onset of new tinnitus was in 58% immediately or within days, in 25% within three months, and in 17% between three months and one year after surgery. The mean severity of postoperative tinnitus was 5.1 points on the VAS. Preoperative tinnitus and presence of arachnoid adhesions had suggestive associations with postoperative tinnitus in initial analyses (p = 0.005 and p = 0.065). However, preoperative tinnitus was the only significant predictor of postoperative tinnitus (p = 0.011). CONCLUSION: Tinnitus is a common condition following MVD for HFS, with a moderate overall severity. Causes behind postoperative tinnitus remain obscure but could be related to those of postoperative hearing loss in this patient population. Clinicians should be aware of tinnitus following MVD and vigilantly monitor its occurrence, to facilitate prevention efforts and optimize outcome for HFS patients undergoing MVD.

Bridge-layered decompression technique for vertebral artery-involved hemifacial spasm: technical note.

BACKGROUND: Hemifacial spasm (HFS) is most effectively treated with microvascular decompression (MVD). However, there are certain challenges in performing MVD for HFS when the vertebral artery (VA) is involved in compressing the facial nerve (VA-involved). This study aimed to introduce a "bridge-layered" decompression technique for treating patients with VA-involved HFS and to evaluate its efficacy and safety to treat patients with HFS. METHODS: A single-center retrospective analysis was conducted on the clinical data of 62 patients with VA-involved HFS. The tortuous trunk of VA was lifted by a multi-point "bridge" decompression technique to avoid excessive traction of the cerebellum and reduce the risk of damage to the facial-acoustic nerve complex. To fully decompress all the responsible vessels, the branch vessels of VA were then isolated using the "layered" decompression technique. RESULTS: Among the 62 patients, 59 patients were cured immediately after the surgery, two patients were delayed cured after two months, and one had occasional facial muscle twitching after the surgery. Patients were followed up for an average of 19.5 months. The long-term follow-up results showed that all patients had no recurrence of HFS during the follow-up period, and no patients developed hearing loss, facial paralysis, or other permanent neurological damage complications. Only two patients developed tinnitus after the surgery. CONCLUSION: The "bridge-layered" decompression technique could effectively treat VA-involved HFS with satisfactory safety and a low risk of hearing loss. The technique could be used as a reference for decompression surgery for VA-involved HFS.

Microvascular Decompression for Hemifacial Spasm without the Use of Neuromonitoring and Fix Retraction: A Single-Center Experience.

AIM: To evaluate outcome of patients with hemifacial spasm surgically treated by microvascular decompression without the use of neuromonitoring and fix retraction. MATERIAL AND METHODS: Of the 78 patients with hemifacial spasm operated by the senior author of this study between 2016 and 2020, 60 patients who were followed up were included and retrospectively investigated. The female:male ratio was 32:28, and the mean age was 42.5 ± 11.5 years (range 23?71 years). All the patients were operated via the lateral retrosigmoid suboccipital infrafloccular approach, and no permanent retractor was employed during the procedures. Additionally, intraoperative neuromonitoring was not performed for any of the patients. RESULTS: Single vessel compression was observed in 77% of the patients, whereas 16% and 6% experienced compression in two and three vessels, respectively. Immediate recovery was achieved in 70% of the patients. Half of the remaining 30% fully recovered within 6 months?2 years. Furthermore, the complaints of 5% of the patients were alleviated, whereas no improvement was observed in 10% of the patients. One patient developed a recurrence. CONCLUSION: Microvascular decompression is a highly effective method for the treatment of hemifacial spasm. In this study, we did not resort to intraoperative neuromonitoring and observed that our postoperative complication rates were consistent with the existing literature.

To be thorough or tailored: influence of the arachnoid dissection range on the surgical outcomes of microvascular decompression for hemifacial spasm.

BACKGROUND: As one of the most fundamental elements in exposure and decompression, the dissection of arachnoid has been rarely correlated with the surgical results in studies on Microvascular decompression (MVD) procedures for Hemifacial spasm (HFS). MATERIALS AND METHODS: Patients' records of the HFS cases treated with MVD from January 2016 to December 2021 in our center was retrospectively reviewed. The video of the procedures was inspected thoroughly to evaluate the range of dissection of arachnoid. Four areas were defined in order to facilitate the evaluation of the dissection range. The correlation between the arachnoid dissection and the surgical outcomes were analyzed. RESULTS: The arachnoid structures between the nineth cranial nerve and the seventh, eighth cranial nerves were dissected in all cases, other areas were entered based on different consideration. The rate of neurological complications of the extended dissection pattern group was higher than that of the standard pattern group (P < 0.05). The procedures in which the arachnoid structure above the vestibulocochlear nerve was dissected, led to more neurological complications (P < 0.05). CONCLUSION: Thorough dissection as an initial aim for all cases was not recommended in MVD for HFS, arachnoid dissection should be tailored to achieving safety and effectiveness during the procedure.

[An analysis of clinical efficacy of microvascular decompression for 21 inpatients suffering from primary hemifacial spasm].

Objective:To assess the effectiveness of microvascular decompression（MVD） in treating inpatients suffering from primary hemifacial spasm（HFS）. Methods:A total of 21 inpatients with HFS underwent MVD. The clinical effect was follow up evaluated according to the clinical symptoms until post operative 6 months. Results:The effective rate of MVD for 1 day, 14 days, 1 month, 3 months and 6 months post-operation was 95.2%, 100%, 100%, 100% and 100%, respectively.one patient had transient tinnitus and the symptom disappeared within 6 days postoperatively.one patient developed postoperative incomplete facial paralysis（HB grade IV facial nerve function, grade Ⅱ） and recovered 6 days after surgery; There was no cerebrospinal fluid leakage, intracranial infection, death or disability occurred during follow-up. Conclusion:Microvascular decompression is a safe and effective method for the treatment of primary hemifacial spasm, which is worthy of clinical promotion.

Comparison of Radiofrequency Ablation and Craniotomy Microvascular Decompression for Treatment of Hemifacial Spasm.

BACKGROUND: Hemifacial spasm (HFS) is distinguished by sudden and involuntary spasms of the facial muscles, predominantly on one side of the face. Microvascular decompression (MVD) is an efficacious surgical technique for treating HFS; however, MVD may occasionally lead to noteworthy postoperative complications. Previously, we reported the successful utilization of an innovative awake computed tomography-guided percutaneous puncture of the stylomastoid foramen for administering radiofrequency ablation (RFA) therapy in the treatment of HFS. STUDY DESIGN: Prospective clinical research study. SETTING: Department of Anesthesiology and Pain Medical Center, Ningbo, China. OBJECTIVES: The aim of this study was to compare and contrast the clinical outcomes and adverse reactions associated with attempts to use RFA and MVD to manage primary HFS. METHODS: Three hundred patients received either RFA or MVD treatment (Group R and Group M). We tracked and recorded each patient's cure rate, remission rate, intraoperative and postoperative complications, short-term and long-term therapeutic outcomes, hospitalization duration, hospitalization expenses, and operation time. RESULTS: One hundred and fifty-eight patients were placed in the R group, and 142 patients were sorted into the M group. In the R group, 87.34% of patients showed improvement, 9.49% experienced relief, and 3.16% experienced treatment failure. Similarly, in the M group, 85.92% of patients showed improvement, 10.56% experienced relief, and 3.52% experienced treatment failure. The difference in therapeutic efficacy between the 2 groups was not significant. However, the M group had significantly lower recurrence rates at 3 months, 6 months, and one year post-operation than the R group did. Notably, the M group also experienced a higher rate of postoperative complications. Among the complications reported in the M group were 25 cases of dizziness or headache (17.6%) following the operation, 22 cases of hearing damage, including one case of complete hearing loss on the side involved, and 28 cases of peripheral nerve injury with abnormal skin sensation. Postoperative facial paralysis occurred in 15 patients, including 10 cases of moderate to severe facial paralysis that were relieved to grade II after one year. In comparison, the R group had 40 cases of grade II and 53 cases of grade III, and no cases of more severe facial paralysis were found. There were also 13 cases of peripheral nerve injury, such as local skin numbness and tenderness. Importantly, there were no cases of facial hematoma, intracranial hemorrhage, infection, or any other complications in either group, and no fatalities occurred during the study period. LIMITATIONS: The limitations of this study are the exclusion of transient postoperative complications, the lack of in-person follow-up with patients, and the potential underestimation of certain complications. CONCLUSION: The short-term outcome was found to be comparable between the 2 treatment modalities. Notably, RFA demonstrates both safety and efficacy as a method for managing primary HFS; however, the procedure may lead to mild facial paralysis. In situations during which surgery is contraindicated, especially among elderly or high-risk surgical patients, percutaneous facial nerve RFA at the stylomastoid foramen may be considered as an alternative therapeutic approach.

White matter structural changes before and after microvascular decompression for hemifacial spasm.

Hemifacial spasm (HFS) is a syndrome characterized by involuntary contractions of the facial muscles innervated by the ipsilateral facial nerve. Currently, microvascular decompression (MVD) is an effective treatment for HFS. Diffusion weighted imaging (DWI) is a non-invasive advanced magnetic resonance technique that allows us to reconstruct white matter (WM) virtually based on water diffusion direction. This enables us to model the human brain as a complex network using graph theory. In our study, we recruited 32 patients with HFS and 32 healthy controls to analyze and compare the topological organization of whole-brain white matter networks between the groups. We also explored the potential relationships between altered topological properties and clinical outcomes. Compared to the HC group, the white matter network was disrupted in both preoperative and postoperative groups of HFS patients, mainly located in the somatomotor network, limbic network, and default network (All P < 0.05, FDR corrected). There was no significant difference between the preoperative and postoperative groups (P > 0.05, FDR corrected). There was a correlation between the altered topological properties and clinical outcomes in the postoperative group of patients (All P < 0.05, FDR corrected). Our findings indicate that in HFS, the white matter structural network was disrupted before and after MVD, and that these alterations in the postoperative group were correlated with the clinical outcomes. White matter alteration here described may subserve as potential biomarkers for HFS and may help us identify patients with HFS who can benefit from MVD and thus can help us make a proper surgical patient selection.

Results from 228 Patients with Hemifacial Spasm Undergoing Microvascular Decompression without Intraoperative Neuroelectrophysiology Monitoring.

BACKGROUND: Intraoperative neuroelectrophysiology monitoring (IONM) has been used to decrease complications and to increase the successful rate of microvascular decompression (MVD) MVD for hemifacial spasm (HFS). Still, it is not available at limited resource centers. We report the outcome of patients undergoing MVD for HFS without using IONM. METHODS: The variables concerning the patients' demographics (age and gender), clinical characteristics, offending vessels (vertebral artery type and non-vertebral artery type), postoperative grade of HFS, and postoperative complications of HFS patients undergoing MVD were retrospectively reviewed and collected. The scoring system provided by the Japan Society for MVD was used to evaluate the postoperative outcome of HFS. Postoperative hearing ability was evaluated according to a subjective assessment of the patients. RESULTS: A total of 228 patients were recruited. Their median age was 51.0 (44.0-57.0) years old. The total cure effect was observed in 207 (90.8%) patients within the first week after the surgery and in 200 (96.1%) patients in a 2-year follow-up. Permanent hearing disturbance happened in 2 patients (0.9%). No patient had permanent unilateral deafness (0%). No postoperative permanent facial paralysis was reported. CONCLUSIONS: MVD without IONM may be performed safely and effectively to treat patients with HFS.

Letter to the editor: fully endoscopic microvascular decompression for hemifacial spasm: a clinical study and analysis.

This article presents a comprehensive analysis of microvascular decompression (MVD) surgery as a treatment option for hemifacial spasm (HFS). Beginning with a thorough literature review, it explores the historical context, prevalence, and underlying mechanisms of HFS, laying a robust foundation for discussing MVD. Various surgical techniques, from traditional microscopic to fully endoscopic approaches, are described, along with their procedural nuances and advantages. Clinical data, including patient demographics and surgical success rates, substantiate the efficacy of MVD in alleviating HFS symptoms. The discussion of postoperative complications provides valuable insights into practical challenges. However, limitations such as single-center design, lack of robust statistical analysis, and absence of comparative data between endoscopic and microscopic approaches diminish the article's potential impact. Recommendations for multicenter collaborations, enhanced statistical analyses, comparative studies, and discussions on surgical training could significantly enhance the article's contribution to neurosurgery practice.

Fully endoscopic microvascular decompression for hemifacial spasm: a clinical study and analysis.

Fully endoscopic microvascular decompression (MVD) of the facial nerve is the main surgical treatment for hemifacial spasm. However, the technique presents distinct surgical challenges. We retrospectively analyzed prior cases to consolidate surgical insights and assess clinical outcomes. Clinical data from 16 patients with facial nerve spasms treated at the Department of Neurosurgery in the First Affiliated Hospital of Bengbu Medical College, between August 2020 and July 2023, were retrospectively examined. Preoperatively, all patients underwent magnetic resonance angiography to detect any offending blood vessels; ascertain the relationship between offending vessels, facial nerves, and the brainstem; and detect any cerebellopontine angle lesions. Surgery involved endoscopic MVD of the facial nerve using a mini Sigmoid sinus posterior approach. Various operative nuances were summarized and analyzed, and clinical efficacy, including postoperative complications and the extent of relief from facial paralysis, was evaluated. Fully endoscopic MVD was completed in all patients, with the offending vessels identified and adequately padded during surgery. The offending vessels were anterior inferior cerebellar artery in 12 cases (75%), vertebral artery in 3 cases (18.75%), and posterior inferior cerebellar artery in 1 case (6.25%). Intraoperative electrophysiological monitoring revealed that the lateral spread response of the facial nerve vanished in 15 cases and remained unchanged in 1 case. Postoperative facial spasms were promptly alleviated in 15 cases (93.75%) and delayed in 1 case (6.25%). Two cases of postoperative complications were recorded-one intracranial infection and one case of tinnitus-both were resolved or mitigated with treatment. All patients were subject to follow-up, with no instances of recurrence or mortality. Fully endoscopic MVD of the facial nerve is safe and effective. Proficiency in endoscopy and surgical skills are vital for performing this procedure.

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.

Experience in treating children with ocular dyskinesia and hemifacial spasm secondary to pontine tumours adjacent to the fourth ventricle and systematic review.

OBJECTIVE: To investigate the treatment plan and prognosis of children with ocular dyskinesia and hemifacial spasm secondary to pontine tumours adjacent to the fourth ventricle. METHODS: In this retrospective study, the clinical information of 10 consecutively collected children with ocular dyskinesia and hemifacial spasm secondary to pontine tumours adjacent to the fourth ventricle was analyzed. All 10 children underwent pontine tumour resection through a trans-cerebellomedullary fissure approach; 4 children underwent preoperative diffusion tensor imaging scans to determine the relationship between the tumour and facial nerve nucleus, and the other 6 children underwent intraoperative deep electroencephalography (EEG) tumour monitoring, in which the tumour electrical discharge activity of the tumour was recorded. A voxel distribution map was established to describe the distribution of the tumour location, and patient prognosis was evaluated through clinical and imaging follow-up. RESULTS: All 10 children achieved total tumour resection; 9 tumours were pathologically suggested to be ganglioglioma (WHO grade I), and 1 was a hamartoma. The symptoms of the original ocular dyskinesia and hemifacial spasm disappeared immediately after the operation. The children were followed up for 4-75 months, and none of the symptoms recurred; four cases with preoperative diffusion tensor imaging showed that the tumour was close to the facial nerve. Four in six intraoperative electrophysiological monitoring showed that the tumour had electrical discharge behaviour, and the tumour distribution map indicates a high density of tumour presence in the facial nerve nucleus and the nucleus of the abducens nerve. CONCLUSIONS: In paediatric patients, the facial symptoms are related to the location and abnormal electrical discharge of the tumour. There is no significant correlation between ocular dyskinesia and the location of the tumour. Conventional antiepileptic therapy for this disease is ineffective, and early surgical intervention for total tumour resection can achieve a clinical curative effect.

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.

Role of a Tortuous Vertebrobasilar Artery and Anchoring Perforators in the Etiology of Hemifacial Spasm.

BACKGROUND: In >70% of patients with hemifacial spasm (HFS), the offending artery is either the anterior inferior cerebellar artery (AICA) or posterior inferior cerebellar artery (PICA), without a tortuous vertebrobasilar artery (VBA). We hypothesized that anchoring perforators around the root exit zone (REZ) of the AICA or PICA might induce vascular deviation and compression. We investigated the occurrence of these perforators from the AICA or PICA and the extent of VBA tortuosity to reveal the pathology of vascular compression. METHODS: This retrospective review included 110 patients after excluding those with vertebral artery (VA) compression alone. The occurrence of perforators was determined according to operative findings within 5 mm of the REZ, and VBA tortuosity was evaluated using MATLAB. We analyzed the association between perforators, VBA tortuosity, and the surgical implications. RESULTS: The occurrence of perforators from the offending AICA or PICA around the REZ was significantly higher in the group without VA compression (Group A) than in the group with VA compression (Group B). VBA tortuosity was significantly lower in Group A. VBA tortuosity was inversely correlated with the presence of AICA or PICA perforators in all 110 patients. Operative results were similar between the groups, although patients with low VBA tortuosity tended to require interposition in decompression procedures. CONCLUSIONS: Anchoring perforators around the REZ play a crucial role in vascular compression for patients with less tortuous VBAs. Moreover, surgeons should be prepared to deal with multiple perforators in a more complicated surgery in cases of less tortuous VBA.

How I do it: endoscopic microvascular decompression for hemifacial spasm associated with anterior inferior cerebellar artery-posterior inferior cerebellar artery common trunk.

BACKGROUND: Multiple vessels from the anterior inferior cerebellar artery-posterior inferior cerebellar artery common trunk (APC) variation of the posterior circulation can cause hemifacial spasm (HFS). METHOD: Endoscopic microvascular decompression (eMVD) was performed using 0° and 30° endoscopes through a retrosigmoid keyhole. The root exit zone (REZ) was decompressed by transpositioning the offending anterior inferior cerebellar artery (AICA) and posterior inferior cerebellar artery (PICA) arising from the APC under excellent endoscopic view. CONCLUSION: eMVD is an advanced, minimally invasive and reliable technique to resolve the neurovascular conflict (NVC) in HFS due to offenders from APC.

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.

[Historical Review of Hemifacial Spasm].

Facial spasm is a disorder characterized by mostly unilateral(hemifacial)involuntary facial muscle contractions, usually caused by vascular compression of the facial nerve. It has been known since ancient times and we can currently find both old medical and artistic presentations. Charles Bell has described at least one definite case(No. IV)with hemifacial spasm in his textbook published in 1830 as did the following physicians like Romberg, Hammond, Gowers, and Brissaud. Babinski coined the name hemispasme facial in 1905 and its English term "hemifacial spasm" appeared in the article by Ehni et al. in 1945. Neurovascular or microvascular decompression surgery was applied to treat this disease in the 1960s and remains a curative therapeutic procedure. Therapy with botulinum toxin appeared as a less invasive procedure in the 1980s and is currently the preferred treatment because of its high safety and efficacy. Secondary facial spasms may occur as a consequence of facial paresis or space-occupying lesion along the facial nerve pathway.

[Prevalences of Trigeminal Neuralgia and Hemifacial Spasm].

Neurosurgeons must have knowledge about the epidemiology of trigeminal neuralgia and facial spasm. The annual incidence of trigeminal neuralgia is 4.3-28.9 per 100,000 persons, with a prevalence of 76.8 per 100,000 persons, increasing with age. It is more common in women and on the right side, with SCA being the most common causative vessel. The long-term efficacy of MVD for trigeminal neuralgia is 80% with complete resolution of pain and 5.2% with complications, which is safe and highly effective when performed by an expert surgeon. Hemifacial spasm has an annual incidence of 0.78/100,000 with a prevalence of approximately 10 per 100,000, increasing with age. It is more common in women and on the left side. AICA alone is the most common causative vessel. The long-term efficacy of MVD for facial spasms is 87.1% with complete resolution of facial spasms and 3.0% with complications. As with trigeminal neuralgia, safe and highly effective treatment can be expected when treated by an expert surgeon.