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.

Retrogasserian trigeminal radiofrequency-thermorhizotmoy for trigeminal neuralgia.

Based on a personal experience of 4200 surgeries, radiofrequency thermocoagulation is useful lesional treatment for those trigeminal neuralgias (TNs) not amenable to microvascular decompression (idiopathic or secondary TNs). Introduced through the foramen ovale, behind the trigemnial ganglion in the triangular plexus, the needle is navigated by radiology and neurophysiological testing to target the retrogasserian fibers corresponding to the trigger zone. Heating to 55-75 °C can achieve hypoesthesia without anaesthesia dolorosa if properly controlled. Depth of anaesthesia varies dynamically sedation for cannulation and lesioning, and awareness during neurophysiologic navigation. Proper technique ensures long-lasting results in more than 75% of patients.

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.

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.

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.

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.

The Primary Afferents of Trigeminal Autonomic Reflex May not be Nociceptive: A Case Report.

Autonomic symptoms have been long noticed coming along with pain in the head, e.g. Trigeminal Neuralgia, trigeminal autonomic cephalalgias. The symptoms show up during pain attacks, so they are assumed to be activated by the nociceptive afferents of the trigeminal nerve. Here, we present a case with hypersalivation as the complication after percutaneous balloon compression for trigeminal neuralgia, although the patient was pain-free after the treatment. A 71-year-old female with excessive salivation on the affected side after percutaneous balloon compression is described. The patient underwent microvascular decompression several years ago, and both the microvascular decompression and the preoperative imaging examination confirmed that there was no offending vessel at the root entry zone of the trigeminal nerve. After the percutaneous balloon compression, the patient was free of pain, but the autonomic symptoms (hypersalivation) still showed up. The autonomic symptoms which usually came along with pain presented solely as post-percutaneous balloon compression complication in the case. Contrary to popular belief, for the patient who was pain-free after percutaneous balloon compression, the transiently overactivated nerve fibers that led to hypersalivation were not nociceptive afferents of the trigeminal nerve.

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.

Intraoperative Brainstem Auditory Evoked Potentials and Postoperative Nausea and Vomiting After Microvascular Decompression.

BACKGROUND: We performed this study to investigate the effect of intraoperative brainstem auditory evoked potential (IBAEP) changes on the development of postoperative nausea and vomiting (PONV) after microvascular decompression (MVD) for neurovascular cross compression. METHODS: A total of 373 consecutive cases were treated with MVD. The use of rescue antiemetics after surgery was used as an objective indicator of PONV. IBAEP monitoring was routinely performed in all. RESULTS: The use of rescue antiemetics was significantly associated with female sex (OR = 3.427; 95% CI, 2.077-5.654; P < 0.001), PCA use (OR = 3.333; 95% CI, 1.861-5.104; P < 0.001), and operation time (OR = 1.017; 95% CI, 1.008-1.026; P < 0.001). A Wave V peak delay of more than 1.0 milliseconds showed a significant relation with the use of rescue antiemetics (OR = 1.787; 95% CI, 1.114-2.867; P = 0.016) and a strong significant relation with the use of rescue antiemetics more than 5 times (OR = 2.426; 95% CI, 1.372-4.290; P = 0.002). CONCLUSIONS: A wave V peak delay of more than 1.0 milliseconds might have value as a predictor of PONV after MVD. More detailed neurophysiological studies will identify the exact pathophysiology underlying PONV after MVD.

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.

Repeat Surgery for Recurrent or Refractory Trigeminal Neuralgia: A Systematic Review and Meta-Analysis.

OBJECTIVE: Surgery can effectively treat Trigeminal neuralgia (TN), but postoperative pain recurrence or nonresponse are common. Repeat surgery is frequently offered but limited data exist to guide the selection of salvage surgical procedures. We aimed to compare pain relief outcomes after repeat microvascular decompression (MVD), percutaneous rhizotomy (PR), or stereotactic radiosurgery (SRS) to determine which modality was most efficacious for surgically refractory TN. METHODS: A PRISMA systematic review and meta-analysis was performed, including studies of adults with classical or idiopathic TN undergoing repeat surgery. Primary outcomes included complete (CPR) and adequate (APR) pain relief at last follow-up, analyzed in a multivariate mixed-effect meta-regression of proportions. Secondary outcomes were initial pain relief and facial numbness. RESULTS: Of 1299 records screened, 61 studies with 68 treatment arms (29 MVD, 14 PR, and 25 SRS) comprising 2165 patients were included. Combining MVD, PR, and SRS study data, 68.8% achieved initial CPR after a repeat TN procedure. On average, 49.6% of the combined sample of MVD, PR, and SRS had CPR at final follow-up, which was on average 2.99 years postoperatively. The proportion (with 95% CI) achieving CPR at final follow-up was 0.57 (0.51-0.62) for MVD, 0.60 (0.52-0.68) for PR, and 0.35 (0.30-0.41) for SRS, with a significantly lower proportion of pain relief with SRS. Estimates of initial CPR for MVD were 0.82 (0.78-0.85), 0.68 for PR (0.6-0.76), and 0.41 for SRS (0.35-0.48). CONCLUSIONS: Across MVD, PR, and SRS, about half of TN patients maintain complete CPR at an average follow-up time of 3 years after repeat surgery. In treating refractory or recurrent TN, MVD and PR were superior to SRS in both initial pain relief and long-term pain relief at final follow-up. These findings can inform surgical decision-making in this challenging population.

Unusual Atrophic Nervus Intermedius in a Patient with Refractory Nervus Intermedius Neuralgia and History of Ipsilateral Sudden-Onset Central Facial Palsy and Sensorineural Hearing Loss: Cadaveric-Clinical Images with Surgical Video.

Nervus intermedius (NI) arises from the superior salivary nucleus, solitary nucleus, and trigeminal tract. It leaves the pons as 1 to 5 roots and travels between the facial and vestibulocochlear nerves before merging with the facial nerve within the internal auditory canal. The mastoid segment of the facial nerve then gives rise to a sensory branch that supplies the posteroinferior wall of the external auditory meatus and inferior pina. This complex pathway renders the nerve susceptible to various pathologies, leading to NI neuralgia. Here, the authors present an unusual intraoperative finding of an atrophic NI in a patient with refractory NI neuralgia and a history of ipsilateral sudden-onset central facial palsy and microvascular decompression for trigeminal neuralgia. The patient underwent NI sectioning via the previous retrosigmoid window and achieved partial ear pain improvement. The gross size of the NI is compared with a cadaveric specimen through stepwise dissection. This case highlights the potential significance of subtle central ischemic events and subsequent atrophy of NI in the pathogenesis of NI neuralgia, as well as the ongoing need to investigate the therapeutic efficacy of nerve sectioning.

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.

Comparison of microvascular decompression, percutaneous radiofrequency rhizotomy, and stereotactic radiosurgery in the treatment of trigeminal neuralgia: A long term quasi-experimental study.

BACKGROUND: Microvascular decompression (MVD), radiofrequency rhizotomy (RFR), and stereotactic radiosurgery (SRS) are surgical techniques frequently used in the treatment of idiopathic trigeminal neuralgia (TN), although the results reported for each of these are diverse. OBJECTIVE: This study aimed to compare long-term pain control obtained by MVD, SRS, and RFR in patients with idiopathic TN. METHODS: To compare the results obtained by MVD, SRS, and RFR we chose a quasi-experimental, ambispective design with control groups but no pretest. A total of 52 participants (MVD n = 33, RFR n = 10, SRS n = 9) were included. Using standardized outcome measures, pain intensity, pain relief, quality of life, and satisfaction with treatment were assessed by an independent investigator. The TREND statement for reporting non-randomized evaluations was applied. Clinical outcomes were evaluated at the initial postoperative period and at 6 months, 1, 2, 3, 4, and 5 years postoperatively. RESULTS: MVD has shown better results in pain scales compared to ablative procedures. Significant differences between groups were found regarding pain intensity and pain relief at the initial postoperative period (p < 0.001) and 6 months (p = 0.022), 1 year (p < 0.001), 2 years (p = 0.002), and 3 years (p = 0.004) after the intervention. Those differences exceeded the thresholds of the minimal clinically important difference. A higher percentage of patients free of pain was observed in the group of patients treated by MVD, with significant differences at the initial postoperative period (p < 0.001) and 6 months (p = 0.02), 1 year (p = 0.001), and 2 years (p = 0.04) after the procedure. Also, a higher risk of pain recurrence was observed in the RFR and SRS groups (HR 3.15, 95% CI 1.33-7.46; p = 0.009; and HR 4.26, 95% CI 1.77-10.2; p = 0.001, respectively) compared to the MVD group. No significant differences were found in terms of quality of life and satisfaction with treatment. A higher incidence of complications was observed in the MVD group. CONCLUSION: Concerning pain control and risk of pain recurrence, MVD is superior to RFR and SRS, but not in terms of quality of life, satisfaction with treatment, and safety profile.

Fully Endoscopic Microvascular Decompression for Trigeminal Neuralgia Caused by Vertebrobasilar Artery: A Case Series Review: 2-Dimensional Operative Video.

BACKGROUND AND OBJECTIVE: Microvascular decompression (MVD) is the most definitive and preferred surgical treatment for trigeminal neuralgia (TN). Treatment of TN caused by the vertebrobasilar artery (VBA) has been reported to be challenging and less satisfactory in complications and recurrence. Endoscopy has been implemented to provide a comprehensive view of neurovascular conflicts and minimize brain tissue stretch injury while exploring the trigeminal nerve. However, there are few retrospective studies on the treatment of TN caused by VBA by fully endoscopic microvascular decompression (E-MVD). This article aimed to illustrate the safety and efficacy of E-MVD for TN caused by the VBA. METHODS: Clinical data for 26 patients with TN caused by the VBA who underwent E-MVD from 2019 to 2022 were retrospectively analyzed. The characteristics of vertebrobasilar-associated TN were summarized. The safety and efficacy of E-MVD for vertebrobasilar-associated TN were estimated based on the analysis of intraoperative manipulation, postoperative symptom relief, and complications. RESULTS: Intraoperatively, the vertebrobasilar artery was regarded as a direct offending vessel in all 26 patients with TN, the vertebral artery in 18 (69.23%) and the basilar artery in 10 (38.46%). In addition to the vertebrobasilar artery, other vessels involved included the superior cerebellar artery in 12 patients, anterior inferior cerebellar artery in 9, posterior inferior cerebellar artery in 1, and veins in 4. All patients underwent E-MVD, and TN was entirely resolved in 26 (100%) patients immediately postoperatively. During the follow-up period of 12-45 months, no recurrence or serious complications were found. There were no serious postoperative complications, such as cerebellar swelling, intracranial hemorrhage, or death. CONCLUSION: E-MVD for vertebrobasilar-associated TN is effective and safe.

Preemptive strategies and lessons learned from complications encountered with microvascular decompression for hemifacial spasm.

OBJECTIVE: Microvascular decompression (MVD) is the only curative treatment modality for hemifacial spasm (HFS). Although generally considered to be safe, this surgical procedure is surrounded by many risks and possible complications. The authors present the spectrum of complications that they met in their case series, the possible causes, and the strategies recommended to minimize them. METHODS: The authors reviewed a prospectively maintained database for MVDs performed from 2005 until 2021 and extracted relevant data including patient demographics, offending vessel(s), operative technique, outcome, and different complications. Descriptive statistics with uni- and multivariable analyses for the factors that may influence the seventh, eighth, and lower cranial nerves were performed. RESULTS: Data from 420 patients were obtained. Three hundred seventeen of 344 patients (92.2%) with a minimum follow-up of 12 months had a favorable outcome. The mean follow-up (standard deviation) was 51.3 ± 38.7 months. Immediate complications reached 18.8% (79/420). Complications persisted in only 7.14% of patients (30/420) including persistent hearing deficits (5.95%) and residual facial palsy (0.95%). Temporary complications included CSF leakage (3.10%), lower cranial nerve deficits (3.57%), meningitis (0.71%), and brainstem ischemia (0.24%). One patient died because of herpes encephalitis. Statistical analyses showed that the immediate postoperative disappearance of spasms and male gender are correlated with postoperative facial palsy, whereas combined vessel compressions involving the vertebral artery (VA) and anterior inferior cerebellar artery can predict postoperative hearing deterioration. VA compressions could predict postoperative lower cranial nerve deficits. CONCLUSIONS: MVD is safe and effective for treating HFS with a low rate of permanent morbidity. Proper patient positioning, sharp arachnoid dissection, and endoscopic visualization under facial and auditory neurophysiological monitoring are the key points to minimize the rate of complications in MVD for HFS.

Application of Sequential Thresholding-Based Automated Reconstruction of the Trigeminal Nerve in Trigeminal Neuralgia.

OBJECTIVE: High-resolution magnetic resonance imaging (MRI) of the trigeminal nerve is indispensable for workup of trigeminal neuralgia (TN) before microvascular decompression; however, the evaluation is often subjective and prone to variability. We aim to develop and assess sequential thresholding-based automated reconstruction of the trigeminal nerve (STAR-TN) as an algorithm for segmenting the trigeminal nerve and contacting structures that will allow for a structured method for assessing neurovascular conflict. METHODS: A total of 42 patients with TN who underwent high-resolution MRI before microvascular decompression in 2022 were included in our study. Segmentation of the trigeminal nerve and contacting structures was performed on preoperative MRI scans using STAR-TN. The segmentations were then evaluated for neurovascular conflict and compared to the preoperative radiology and operative notes. Geometric features, including the area of contact and distance to conflict, were extracted. RESULTS: Of the 42 patients, 32 (76.2%) were found to show neurovascular conflict based solely on their STAR-TN segmentations and 10 (23.8%) were found to not show neurovascular conflict. Compared with the intraoperative findings, this resulted in a sensitivity of 78.0% and specificity of 100%. In contrast, assessments of neurovascular conflict by radiologists using only 2-dimensional MRI views had a sensitivity of 68.3% and specificity of 100%. Of the 32 patients with neurovascular conflict, 29 (90.9%) had conflict within the root entry zone. Overall, the patients had a median area of contact of 10.66 mm2. CONCLUSIONS: STAR-TN allows for 3-dimensional visualization and identification of neurovascular conflict with improved sensitivity compared with neuroradiologist assessments from MRI slices.

Risk of Bone Wax Migration During Retrosigmoid Craniotomy for Microvascular Decompression: Case-Control Study.

BACKGROUND AND OBJECTIVES: Bone wax is a flexible hemostatic agent commonly used for surgery in the posterior cranial fossa to control bleeding from the mastoid emissary vein. A large amount of bone wax can migrate into the sigmoid sinus through the mastoid emissary canal (MEC). We aimed to identify clinical factors related to intraoperative bone wax migration through the MEC during microvascular decompression (MVD) surgery, which may result in sigmoid sinus thrombosis. METHODS: We retrospectively collected the clinical data of patients with trigeminal neuralgia, hemifacial spasm, or trigeminal neuralgia accompanied by painful tic convulsif who underwent MVD. Basic information and the residual width and length (from the bone surface to the sigmoid sinus) of the MEC on computed tomography images were collected. We compared the collected clinical data between 2 groups of cases with and without intraoperative bone wax migration in the sigmoid sinus. RESULTS: Fifty-four cases with intraoperative bone wax migration and 187 patients without migration were enrolled. The t -test revealed significant differences in the width and length of the MEC ( P = .013 and P = .003, respectively). These variables were identified as significant factors in predicting intraoperative bone wax migration using multivariate logistic regression analysis. CONCLUSION: The large size of the MEC may be related to intraoperative bone wax migration into the sigmoid sinus in MVD. Neurosurgeons should be aware of these risks. Bone wax should be applied appropriately and hemostasis should be considered to control bleeding from the mastoid emissary vein in patients with a large MEC.

Abnormal Rhomboid Lip and Choroid Plexus Should be Valued in Microvascular Decompression for Vestibulocochlear Diseases.

BACKGROUND: Surgical outcomes for functional vestibulocochlear diseases vary, and the influencing factors are not fully understood. The role of a rhomboid lip (RL) and choroid plexus (CP) in microvascular decompression (MVD) of the vestibulocochlear nerve has not been studied. This study aims to evaluate the surgical efficacy of MVD for vestibulocochlear diseases, with and without addressing the RL and CP, to enhance our understanding of their etiology. METHODS: A total of 15 patients who underwent MVD for the vestibulocochlear nerve between 2013 and 2022 were retrospectively identified and followed up. The patients were classified into 4 categories: vestibular paroxysmia (VP), benign positional paroxysmal vertigo (BPPV), and Meniere disease (MD). The fourth was a "tinnitus" group. The relief of symptoms, recurrence, satisfaction after surgery, available relevant imaging studies, and intraoperative observation data were evaluated. RESULTS: Following MVD, 6 of the 7 patients in the VP group, the 1 patient in the BPPV group, and 1 of 2 patients in the MD group were completely relieved of vertigo. The seventh VP patient showed significant improvement. The 5 patients in the "tinnitus" group remained unchanged. Retrospectively, 4 patients from the VP, BPPV, and MD groups who underwent RL incision and CP excision were also free of vertigo, although vascular compression was not confirmed in these cases. CONCLUSIONS: MVD is generally considered a useful treatment for VP and could also be effective in managing recurrent vertigo caused by BPPV and MD. Our results highlight the potential role of an abnormal RL and CP in the development of vertigo symptoms. Patients presenting with "tinnitus" require further investigation and might not be suitable for MVD.