Multimodal image fusion–guided microvascular decompression for hemifacial spasm: a comparative clinical study

Objective To explore the consistency of neurovascular relationships between multimodal image fusion 3D reconstruction and intraoperative findings in microvascular decompression (MVD) for primary trigeminal neuralgia (PTN). Methods A retrospective analysis was conducted on the clinical data of 50 PTN patients treated with MVD at Department of Neurosurgery, Qingdao University Hospital from January to November 2018. All subjects underwent three-dimensional time-flying magnetic resonance angiography (3D-TOF-MRA) and three-dimensional cyclic phase steady-state acquisition rapid imaging (3D-FIESTA) sequences. Then, the 3D-slicer software was used to reconstruct the multimodal fusion 3D image. Multimodal image fusion 3D reconstruction images and surgical video were analyzed to determine the offending vessels responsible for trigeminal neuralgia. At the same time, the direction of compression, compression site and compression degree of the trigeminal nerve were analyzed. Kappa consistency test method was used to judge the consistency of the two approaches above. Results With MVD set as the standard, the accuracies of multimodal image fusion 3D reconstruction images in determining the offending vessels, direction of compression, compression site and the degree of compression were 92.0% (46/50), 92.0% (46/50), 96.0% (48/50) and 58.0% (29/50), respectively. Multimodal image fusion 3D reconstruction images and MVD showed high consistency in judging offending vessels, compression direction and compression position (Kappa values: 0.729, 0.903 and 0.955 respectively, all P<0.001). However, the consistency was poor in judging the degree of compression of offending vessels to the trigeminal nerve (Kappa value=0.227, P=0.002). The degree of compression was higher in intraoperative findings of MVD than that revealed by multimodal image fusion three-dimensional reconstruction (mean values: 2.57 and 1.58 respectively, Z=-4.499, P<0.001). Conclusions Preoperative multi-modal image fusion 3D reconstruction could help accurately determine the offending vessel, compression direction and compression position of PTN, which seems highly consistent with intraoperative findings of MVD. Preliminary speculation could be used as one of the methods facilitating preoperative diagnosis. Key words: Trigeminal neuralgia; Multimodal image fusion; Microvascular decompression; Neurovascular relationship; Computer-aided diagnosis

The neurovascular conflict (NVC) at the brainstem exit zone of the facial nerve is considered the primary etiology of primary hemifacial spasm (HFS). Therefore, microvascular decompression (MVD) has become the preferred treatment for HFS. Successful neurovascular decompression can achieve significant therapeutic effects, and accurately identifying the site of compression is crucial for the success of this surgery. Detailed diagnostic neuroimaging plays an important role in accurately identifying the site of compression.The purpose of this study is to explore the feasibility and predictive value of preoperative visualization assessment of the neurovascular relationship in HFS using 3D Slicer software based on multimodal imaging fusion. This aims to reduce the omission of responsible vessels and lower the incidence of postoperative complications, thereby potentially improving the efficacy and safety of the surgery. This study retrospectively analyzed 80 patients with HFS who underwent MVD surgery. All patients underwent preoperative cranial MRI scans, including the 3D-FIESTA and the 3D-TOF MRA sequences. Three-dimensional models were reconstructed from the multimodal MRI images using 3D Slicer software. Independent observers, who were blinded to the surgical outcomes, evaluated the neurovascular relationships using both the three-dimensional models and multimodal MRI images. The assessment results were compared with intraoperative findings, and statistical analysis was conducted using SPSS 22.0 software. The agreement between preoperative assessment using the 3D-TOF MRA sequence combined with the 3D-FIESTA sequence and intraoperative findings was represented by a Kappa value of 0.343, while the Kappa value for agreement between three-dimensional reconstruction and intraoperative findings was 0.637. There was a statistically significant difference between the two methods ( X2 = 18.852, P = 0.001 ). The sensitivity and specificity of the 3D-TOF MRA sequence combined with the 3D-FIESTA sequence for evaluating neurovascular relationships were 92.4% and 100%, respectively, while for three-dimensional reconstruction, both were 100%. The Kappa value for agreement between preoperative the 3D-TOF MRA sequence combined with the 3D-FIESTA sequence prediction of offending vessels and intraoperative findings was 0.625, while the Kappa value for agreement between three-dimensional reconstruction and intraoperative findings was 0.938, showing a statistically significant difference ( X2 = 317.798, P = 0.000 ). The Kappa value for agreement between preoperative the 3D-TOF MRA sequence combined with the 3D-FIESTA sequence assessment of the anatomical location of facial nerve involvement in neurovascular compression and intraoperative findings was 0.608, while the Kappa value for agreement between three-dimensional reconstruction and intraoperative findings was 0.918, also showing a statistically significant difference ( X2 = 504.647, P = 0.000 ). The preoperative visualization assessment of neurovascular relationships in HFS using 3D Slicer software based on multimodal imaging fusion has been demonstrated to be reliable. It is more accurate than combining the 3D-TOF MRA sequence with the 3D-FIESTA sequence and shows higher consistency with intraoperative findings. This method provides guidance for surgical procedures and thereby potentially enhances the efficacy and safety of surgeries to a certain extent.

Neurovascular compression (NVC) is the main cause of hemifacial spasm (HFS) or trigeminal neuralgia (TN), and frequently occurs at the root entry zone of cranial nerves. Microvascular decompression (MVD) is an effective surgical treatment for TN and HFS caused by NVC. The accurate preoperative diagnosis of NVC is crucial to the evaluation of MVD as an appropriate treatment for TN and HFS. Three-dimensional (3D) time-of-flight magnetic resonance angiography (3D TOF MRA) and high resolution T2-weighted imaging (HR T2WI) are used to detect NVC prior to MVD; however, this combination alone has certain disadvantages. Multimodal image fusion (MIF) may combine two or more images from the same or different modalities, allowing neurosurgeons to use the reconstructed 3D model to observe anatomical details more clearly from different perspectives. The aim of the present meta-analysis was to evaluate the effect of 3D MIF based on 3D TOF MRA combined with HR T2WI in the preoperative diagnosis of NVC, and thus to evaluate its clinical application value in the preoperative evaluation of MVD. Relevant studies available on PubMed, Embase, Web of Science, Scopus, China National Knowledge Infrastructure and the Cochrane Library, and published from the inception of each database to September 2022, were retrieved. Studies using 3D MIF based on 3D TOF MRA combined with HR T2WI to diagnose NVC in patients with TN or HFS were included. The Quality Assessment of Diagnostic Accuracy Studies checklist was used to evaluate the quality of the included studies. The statistical software Stata 16.0 was used to perform the meta-analysis. Data extraction was performed by two independent investigators and discrepancies were resolved by discussion. Pooled sensitivities, specificities, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and the area under the receiver operating characteristic curve (AUROC) were calculated as the main summary effect size. The I² and Q-test were used to assess heterogeneity. The present search identified 702 articles, of which 7 (comprising 390 patients) fulfilled the inclusion criteria. Bivariate analysis indicated that the pooled sensitivity and specificity of 3D MIF based on 3D TOF MRA combined with HR T2WI for detecting NVC were 0.97 (95% CI, 0.95-0.99) and 0.89 (95% CI, 0.77-0.95), respectively. The pooled PLR was 8.8 (95% CI, 4.1-18.6), the pooled NLR was 0.03 (95% CI, 0.02-0.06) and the pooled DOR was 291 (95% CI, 99-853). The AUROC was 0.98 (95% CI, 0.97-0.99). The studies had no substantial heterogeneity (I2=0; Q=0.000; P=0.50). The present results suggested that 3D MIF based on 3D TOF MRA combined with HR T2WI had excellent sensitivity and specificity for diagnosing NVC in patients with TN or HFS. Therefore, this method should serve a key role in MVD preoperative evaluation.

To explore the application value of preoperative multimodal image fusion technique in microvascular decompression (MVD) surgery via the suboccipital retrosigmoid approach. Comprehensive data of 13 patients with primary trigeminal neuralgia (TN) and 13 patients with hemifacial spasm (HFS) treated by MVD surgery via the suboccipital retrosigmoid approach at the Department of Neurosurgery in Zhuhai People's Hospital from January 2021 to December 2021 were retrospectively analyzed. Preoperatively, all patients underwent cranial thin-section computed tomography and magnetic resonance examinations. Three-dimensional (3D) digital images of the skull, brainstem, nerves, and blood vessels were constructed by the 3D-slicer software or RadiAnt DICOM Viewer, which were then applied to design the surgical approach and surgical plan. The multimodal image fusion results, clinical characteristics, intraoperative data, surgical outcomes, and complications of all patients were summarized. The 3D digital images after fusion reconstruction can vividly show the anatomical relationship between the skull, brainstem, nerves, and blood vessels and was helpful to tailor the surgical strategy. All 26 patients underwent a smooth surgery. During the surgery, the key points were accurately located, the corners of the transverse sinus and sigmoid sinus were completely exposed, and no venous sinus injury occurred in all 26 patients. The key point was approximately located at the top point of the digastric groove, 12.3±0.46mm vertically above and 6.3±0.6mm laterally to the Frankfurt horizontal plane. The average cranial opening time was 30.4 (±3.6) min, and the mean operating time was 104.7 (±12.1) min. The diameter of the bone window was about 2.0 cm-3.0cm, and the bone flap was restored. Among the 13 patients with primary TN, 12 (92.3%) exhibited complete relief of pain and 1 had significant relief. Complications of surgery included facial sensory numbness in 1 case, vertigo in 2 cases, and herpes at the corners of the mouth in 1 case. Of the 13 patients with HFS, 12 (92.3%) had complete relief of facial twitching symptoms and 1 had significant relief, and the complications included mild facial palsy in 2 (15.4%) cases and facial sensory numbness in another 2 (15.4%) cases. The mean follow-up time after surgery ranged from 6-16months, and 1 of 26 patients experienced recurrence of HFS during the follow-up period. Preoperative multimodal image fusion technology can provide adequate preoperative assessment for patients and assistance in designing surgical approaches, which is an important guideline for MVD surgery via the suboccipital retrosigmoid approach for primary TN and facial muscle spasm.

Introduction: Endoscopic microvascular decompression (MVD) with intraoperative neurophysiological monitoring (IONM) is increasingly being adopted as the standard approach for treating neurovascular compression syndromes in the cerebellopontine angle. This study aims to evaluate the initial outcomes of the first five cases of endoscopic MVD with IONM. Materials and Methods: This prospective study included the first five cases of endoscopic MVD with IONM performed for trigeminal neuralgia and hemifacial spasm at the Department of Neurosurgery – Spine surgery, Hanoi Medical University Hospital between September 2024 and February 2025. The neurophysiological monitoring techniques used included brainstem auditory evoked potentials (BAEP), brainstem trigeminal evoked potentials (BTEP), lateral spread response (LSR), and Zhong-Lee response (ZLR). Treatment outcomes for trigeminal neuralgia were assessed using the Barrow Neurological Institute (BNI) pain intensity scale, while hemifacial spasm outcomes were evaluated using the Hemifacial Spasm (HFS) score. Results: Three cases of hemifacial spasm had a preoperative mean HFS clinical score of 12.67, which improved to 0 postoperatively, with a preoperative quality of life (QoL) of 73.3%, improving to 0% postoperatively. All three cases involved compression by the anterior inferior cerebellar artery (AICA) and exhibited intraoperative LSR, which disappeared after decompression, accompanied by a positive Zhong-Lee response. Two cases of medically refractory trigeminal neuralgia were classified as BNI grade IV and V preoperatively, with immediate postoperative improvement to BNI grade I. The compressing structures were the superior cerebellar artery (SCA) and Dandy’s vein. In both cases, BTEP waves in the V2 and V3 branches emerged following decompression. Although all five cases demonstrated intraoperative BAEP amplitude reduction, postoperative hearing function was preserved. Conclusions: Endoscopic MVD with IONM enhances surgical success rates and reduces postoperative hearing loss. Keywords: trigeminal neuralgia, hemifacial spasm, endoscopic microvascular decompression, Jannetta procedure, intraoperative neurophysiological monitoring. References McLaughlin MR, Jannetta PJ, Clyde BL, Subach BR, Comey CH, Resnick DK. Microvascular decompression of cranial nerves: lessons learned after 4400 operations. J Neurosurg. 1999;90(1):1-8. doi:10.3171/JNS.1999.90.1.0001 Zhao Z, Chai S, Xiao D, et al. Microscopic versus endoscopic microvascular decompression for the treatment of hemifacial spasm in China: A meta-analysis and systematic review. Journal of Clinical Neuroscience. 2021;91:23-31. doi:10.1016/j.jocn.2021.06.034 Zheng X, Zhang B, Shao D, et al. Fully endoscopic microvascular decompression for hemifacial spasm: a clinical study and analysis. Neurosurg Rev. 2024;47(1). doi:10.1007/S10143-024-02311-5 Montano N, D’Alessandris QG, Grilli F, et al. Abnormal electromyographical trigeminal activation through stimulation of the offending artery (Z-L response): An intraoperative tool during microvascular decompression for trigeminal neuralgia. Cephalalgia. 2024;44(11). doi:10.1177/03331024241273913 Polo G, Fischer C, Sindou MP, et al. Brainstem auditory evoked potential monitoring during microvascular decompression for hemifacial spasm: intraoperative brainstem auditory evoked potential changes and warning values to prevent hearing loss--prospective study in a consecutive series of 84 patients. Neurosurgery. 2004;54(1):97-106. doi:10.1227/01.NEU.0000097268.90620.07 Pham Hoang Anh, Duong Dai Ha, Chu Thanh Hung et al. Surgical outcomes of fully endoscopic microvascular decompression for hemifacial spasm at VietDuc University Hospital. Journal of Medical Research. 2023; 162(1):37-45 Bui Huy Manh. Application of microvascular decompression for trigeminal neuralgia. PhD dissertation in Medicine. 2015. Guo X, Zhang C, Li Y, Li X, Ma X, Li W. Fully Endoscopic Microvascular Decompression for Hemifacial Spasm Using Improved Retrosigmoid Infrafloccular Approach: Clinical Analysis of 81 Cases. Operative Neurosurgery. 2022;23(1):40-45. doi:10.1227/ONS.0000000000000221 Jiang H, Wang P, Zhou D, Zeng L, Lin B, Wu N. Fully endoscopic microvascular decompression for hemifacial spasm. Exp Ther Med. 2022;24(1). doi:10.3892/ETM.2022.11410 Zhu J, Zhang X, Zhao H, Tang Y Da, Ying TT, Li ST. Utility of Brainstem Trigeminal Evoked Potentials in Patients With Primary Trigeminal Neuralgia Treated by Microvascular Decompression. J Craniofac Surg. 2017;28(6):e571-e577. doi:10.1097/SCS.0000000000003882 Lee SH, Park BJ, Shin HS, Park CK, Rhee BA, Lim YJ. Prognostic ability of intraoperative electromyographic monitoring during microvascular decompression for hemifacial spasm to predict lateral spread response outcome. J Neurosurg. 2017;126(2):391-396. doi:10.3171/2016.1.JNS151782 Cho KR, Lee HS, Kim M, Park SK, Park K. Optimal method for reliable lateral spread response monitoring during microvascular decompression surgery for hemifacial spasm. Scientific Reports 2023 13:1. 2023;13(1):1-13. doi:10.1038/s41598-023-49008-1 Thirumala PD, Altibi AM, Chang R, et al. The utility of intraoperative lateral spread recording in microvascular decompression for hemifacial spasm: A systematic review and meta-analysis. Neurosurgery. 2020;87(4):E473-E484. doi:10.1093/NEUROS/NYAA069 Yun GY, Ahn JM, Park JH, Oh HJ, Shim JJ, Yoon SM. Preliminary Report of Fully Endoscopic Microvascular Decompression. J Korean Neurosurg Soc. 2024;67(6):646-653. doi:10.3340/JKNS.2024.0003 Lee H, Park K, Park SK, Lee DH. Hearing Loss after Microvascular Decompression Surgery Performed with the Retro-Mastoid Suboccipital Approach: A Single-Center Study, Analysis of 682 Cases. J Neurol Surg B Skull Base. 2025;86(S 01):S357. doi:10.1055/S-0045-1803370. Download file PDF

Multimodal medical image fusion technology optimizes image content by integrating images from diverse modalities, such as Computed Tomography (CT), Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI), and Single Photon Emission Computed Tomography (SPECT), while retaining critical information. With the rapid advancements in medical imaging technology, single-modal approaches have limitations in capturing comprehensive anatomical or functional characteristics. As a result, researchers are increasingly turning to multimodal fusion methods to enhance diagnostic accuracy and provide richer data for classification, detection, and segmentation tasks. In particular, during the perioperative period, multimodal image fusion plays a crucial role in surgical planning, intraoperative navigation, and postoperative evaluation, enabling precise localization of lesions and improving clinical decision-making. This paper presents a survey of the latest literature on medical image fusion, covering three major approaches: traditional methods, model-based methods, and learning-based methods. It discusses the advantages and limitations of each approach, with a particular emphasis on traditional image processing techniques, model-based fusion methods, and the integration of emerging deep learning (DL) technologies. Comparative experimental analysis highlights performance differences among these methods in terms of information retention, computational efficiency, and clinical applicability. Finally, the paper reviews performance evaluation metrics for multimodal fusion and provides recommendations for future research to further promote the widespread adoption of this technology in clinical diagnostics and intelligent healthcare.

Several studies have investigated the relation between intraoperative abnormal muscle response (AMR) findings and postoperative results in patients undergoing microvascular decompression (MVD) for hemifacial spasm (HFS). However, there is some debate over the reliability of AMR as an indicator of postoperative outcome. We investigated whether AMR findings obtained during MVD reflect postoperative outcome in patients with HFS. Subjects were 60 HFS patients who underwent AMR monitoring during MVD. AMR recordings were obtained from the mentalis muscle by electrical stimulation of the temporal branch of the facial nerve and from the orbicularis oculi muscles by stimulation of the marginal mandibular branch. Surgical outcome was compared with AMR findings at the completion of MVD. Mean follow-up was 61 months. HFS resolved completely in 50 patients in whom AMR disappeared intraoperatively and in 5 patients in whom the AMR amplitude was decreased at the end of MVD. Four patients showed HFS at the final follow-up examination despite cessation or decrease of AMR during surgery. In 1 patient, preoperative AMR waveforms persisted throughout MVD, but the postoperative outcome was excellent. Our findings suggest that intraoperative cessation or decreased amplitude of AMR at the end of surgery indicates a high likelihood of postoperative relief of HFS. We believe that intraoperative AMR monitoring is useful in MVD surgery for HFS.

We retrospectively compared the outcome of microvascular decompression (MVD) for hemifacial spasm (HFS) associated with the vertebral artery (VA) with that of MVD for HFS unrelated to the VA. Between April 2008 and April 2015, 22 patients with VA-associated HFS underwent MVD at our institution. The median follow-up period was 28months (range, 12-90months). Results were classified as excellent in 19 patients (86%), good in one (5%), fair in one (5%), and poor in one (5%). Immediate complications developed in five patients (23%), and one of these complications (5%) was permanent. The surgical outcome of MVD for VA-associated HFS was similar to that of MVD for HFS unrelated to the VA; however, the incidence of complications was significantly more frequent in patients whose VA compressed the more proximal portion of the facial nerve root exit zone from the caudal side at the pontomedullary sulcus. We conclude that preoperative evaluation of VA compression patterns is important to predict the difficulty of the planned MVD procedure.

Microvascular decompression (MVD) is the first choice of surgery for hemifacial spasm (HFS). MVD surgery for vertebral artery (VA)-associated HFS is more difficult than for non-VA-associated HFS. There is controversy about the cure rate and complication of MVD for HFS in previous studies. We searched PubMed, Web of Science, and Embase for relevant publications. Based on the search results, we compared the outcomes of MVD for VA-associated HFS and non-VA-associated HFS. At the same time, we analyzed spasm-free rates and the complications and assessed the relationship between VA-associated HFS and gender, left side, and age. For analysis, six studies that included 2952 patients in the VA-associated group and 604 in the non-VA-associated group were selected. The effective rate of MVD was not significantly different between both groups (OR = 1.16, 95% CI 0.81-1.67, P = 0.42). Compared to non-VA-associated group, the transient complications (OR = 0.64, 95% CI 0.46-0.89, P = 0.008) and permanent complications (OR = 0.28, 95% CI 0.15-0.54, P = 0.0001) occurred more frequently in VA-associated group. The rate of hearing loss was significantly higher in VA-associated HFS than non-VA-associated HFS (OR = 0.35, 95% CI 0.19-0.64, P = 0.0007); the facial paralysis after operation was not significantly different between both groups (OR = 1.25, 95% CI 0.91-1.72, P = 0.17). There were older patients (WMD = 3.67, 95% CI 3.29-4.05, P < 0.00001) and more left-sided HFS (OR = 0.23, 95% CI 0.19 - 0.29, P < 0.0002) in the VA-associated HFS group than non-VA-associated HFS group, while the non-VA-associated HFS group was female-dominated (OR = 1.58, 95% CI 1.32 - 1.89, P < 0.00001). Both groups achieved good results in MVD cure rates. In VA-associated HFS, the complication rate of decompression and the rate of hearing loss after operation were higher than in non-VA-associated HFS, but the facial paralysis after operation was similar in both groups, and most complications were transient and disappeared during follow-up. VA-associated HFS is more prevalent in older adults, less prevalent in women, and more predominantly left-sided. More clinical studies are needed to better compare the efficacy and complication of MVD between both groups.

The lateral spread response (LSR) on preoperative facial electromyogram (EMG) is a useful tool in evaluating patients with hemifacial spasm (HFS). There may be some instances where the LSR does not appear on the preoperative EMG, thus disrupting the diagnosis and treatment of HFS. In this study, we evaluated the patients who did not exhibit LSR on preoperative EMG but underwent microvascular decompression (MVD) for hemifacial spasm. We searched for patients who underwent MVD for HFS but had an absence of LSR on preoperative EMG between January 2016 and June 2018. Surgical outcomes were evaluated at 1, 3, and 6months after surgery. Follow-up facial EMG was performed 3months after surgery. Results were divided into two categories: (1) spasm relief within 24h of surgery and (2) spasm was observed immediately post-operation. The following parameters were analyzed when comparing between the two groups: age, sex, affected side, duration of symptoms, and offending vessel(s). A total of 306 patients underwent MVD for HFS during the study period. Among them, 13 (4.2%) patients had no LSR on preoperative EMG. Eight patients (61.5%) were female and five patients were male. The 13 patients had a mean age of 51years. All patients exhibited probable offending vessels in the root exit zone (REZ) of the facial nerve on preoperative magnetic resonance (MR) imaging that was confirmed during surgery. Seven patients were free of HFS immediately after surgery, though six patients were not. Only one (7.7%) patient had persisted symptom 6months after surgery. No patients experienced recurrence of spasm, nor exhibited abnormal waves on follow-up facial EMG. LSR on facial EMG is a valuable tool for evaluating hemifacial spasm. However, although LSR did not appear on preoperative EMG, if the patient presents with typical symptoms and the offending vessels are identified on MRI, we expect good results after MVD for HFS.

O179 Intraoperative blink reflex in microvascular decompression for hemifacial spasm. A case report and proposal of a new method to monitor the efficiency of decompression

Objectives: The objective of this study is to investigate the clinical characteristics, intraoperative findings, complications, and outcomes in these patients with hemifacial spasm (HFS) caused by venous compression.Methods: We analyzed 15 patients who underwent microvascular decompression (MVD) for HFS caused by venous compression performed at the University of Pittsburgh Medical Center between 1 January 2000 and 31 December 2007. Thirteen of 15 patients underwent repeat MVD, and two patients underwent their first MVD. Clinical data were collected to verify vein as real offending vessel for all of 15 patients with HFS. The mean follow-up period was 4·13 years (range: 1·29–6·76 years).Results: Thirteen patients with repeat MVDs had vein as the offending vessel, such as series of small venule, small veins, and dilated venous stump. The remaining two patients who underwent the first MVD had vein as the only offending vessel. In the first MVD for 13 patients, lateral spread response (LSR) disappeared in five patients (38·5%). In the repeat MVD for these 13 patients, LSR disappeared after the vein was decompressed completely in nine patients (69·2%). An excellent surgical outcome was observed in all the 11 patients with four patients lost during the follow-up period. Post-operative complications were observed in 12 patients included hearing loss, cerebrospinal fluid leakage, worsening facial palsy, difficulty swallowing, dilpopia, and ataxia.Conclusions: Vein can play an important role and can be the offending vessel in MVD for HFS. Women with platysmal involvement and tonus seem to have higher chance of vein as an offending vessel. These patients that have residual LSR at the end of the procedure should undergo exploration for a vein to prevent persistent HFS. Intraoperative monitoring with LSR is an effective tool to evaluate adequate decompression to vein. Although the long-term outcome is excellent for venous compression, the complication rate is much higher. To decrease the complication rate, gentle retraction of the cerebellum and ‘low-power’ coagulation of the vein might be helpful.

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

Hemifacial spasm (HFS) is occasionally caused by neurovascular compression (NVC) from a tortuous and elongated vertebral artery (VA), often with dolichoectatic changes. The aim of this study was to determine whether patients with HFS and VA involvement as an offending vessel exhibit clinicosurgical features distinct from those patients without VA involvement. Demographics, clinical and surgical characteristics, and treatment outcomes of consecutive patients who underwent microvascular decompression (MVD) for HFS at a single institution from October 2011 to December 2016 were retrospectively reviewed. In addition, relevant publications were reviewed for the clinicosurgical characteristics of patients with HFS and tortuous VA involvement. Of 279 included patients (192 female, mean age 53.9 years), 100 (35.8%) had involvement of a tortuous VA as the offending vessel (VA+ group) and 179 (64.2%) did not (VA- group). The VA+ group had a significantly higher proportion of males (OR 2.01, 95% CI 1.19-3.38; p = 0.01) and significantly higher left-sided preponderance (OR 0.37, 95% CI 0.22-0.62; p = 0.002) compared with the VA- group. For 3 patients (3%) in the VA+ group, the VA was the sole offending vessel responsible for HFS, while the remaining 97 patients (97%) had multiple offending vessels involved, including the anterior inferior cerebellar artery (AICA) and/or posterior inferior cerebellar artery (PICA). Compared with the VA- group, the VA+ group had a higher percentage of PICA involvement (50% vs 33%) and lower percentage of AICA involvement (61% vs 78.2%). No significant difference was observed in the surgical outcomes (p = 0.58) or incidence of complications (p = 0.90) between the two groups. Additionally, the literature review indicated that patients with HFS and tortuous VA involvement in previous studies tended to show a weaker female preponderance and a stronger left-sided predominance compared with those without VA involvement. Patients with HFS involving the VA as the offending vessel had distinct clinicosurgical features compared with those without VA compression. Furthermore, during MVD for VA-involved HFS, special attention is required to avoid missing concurrent small arteries beneath the VA on the NVC site of the affected facial nerve.

Objective To evaluate the clinic effects of electrophysiological monitoring during the microvascular decompression(MVD) for hemifacial spasm(HFS) . Methods From June 2012 to May 2014, 76 HFS patients were performed with intraoperative abnormal muscle reaction(AMR) and facial-motor evoked potentials(facial-MEP) during MVD. The therapeutic effect was evaluated at 1 week and 3 months postoperation. The relationship between AMR changes and prognosis, Facial-MEP and the postoperative early facial paralysis in monitoring period were analyzed. Results A single offending vascular was found in 60 patients and multiple offending vessels were found in 16 patients. Typical AMR(complete-disappeared, partial-disappeared, non-disappeared) was observed in all patients. Relief rate at 1 week and 3 months postoperation was 85.5%(65/76) and 92.1%(70/76), respectively. Relief rate in AMR-complete-disappeared group was higher than that of AMR-partial-disappeared group, but the correlation in the both group was not statistically significant(all P values>0.05). The therapeutic effect in AMR-complete-disappeared group and AMR-partial-disappeared group were significanly better than that in AMR-non-disappeared group (all P values<0.05). Conclusions Intraoperative AMR monitoring is helpful in MVD surgery for HFS, which may improve the therapeutic effect. Key words: Hemifacial spasm; Microvascular decompression surgery; Facial nerve; Evoked potentials, motor; Abnormal muscle reaction