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Background and Objectives: Hemifacial spasm (HFS) is a rare movement disorder characterized by brisk, irregular, involuntary, and unilateral contraction of the facial musculature. This systematic review aims to synthesize the existing literature and compare the use of 2 microvascular decompression (MVD) techniques-transposition and interposition-used in the treatment of HFS., Methods: A retrospective systematic review of randomized controlled trials, meta-analyses, case-control studies, and case series examining transposition and/or interposition during MVD for HFS was performed using PubMed, Embase, and Scopus databases. Data extracted included study objective and size, surgical method, demographic information, operative technique notes, number and location of offending vessels, complications, follow-up duration, rate of spasm freedom at last follow-up, and additional outcomes. Cohorts of at least 20 patients with HFS treated with MVD reported in studies explicitly mentioning surgical techniques were included., Results: PubMed, Embase, and Scopus database searches yielded 1300 records, of which 528 were duplicates. Sixty-two studies reporting 68 cohorts met inclusion criteria, including 5 on transposition, 51 on interposition, and 6 using both techniques. Interposition was used in 18 627 cases, and transposition was used in 810 cases. Spasm freedom at final follow-up was similar between transposition and interposition (90.4% vs 89.6%). Complication rates were similar between techniques, with the largest difference being higher rates of temporary facial nerve weakness/palsy among the transposition series (9.52%) than the interposition series (6.03%)., Conclusion: Both transposition and interposition are safe and effective techniques for MVD in patients with HFS. Available literature to date does not provide conclusive evidence that 1 method is superior to the other in safety or efficacy although there are specific instances that favor the use of interposition. A prospective trial would be required to delineate the true differences between these techniques., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Background: Botulinum toxin is an effective treatment for hemifacial spasm in elderly patients. However, some patients do not tolerate the side effects and frequency of botulinum toxin treatments., Objectives: The purpose of this study was to evaluate the characteristics and outcomes of a cohort of elderly patients referred by neurologists for surgical decompression of the facial nerve following botulinum toxin treatment., Methods: In a prospective cohort study, logistic regression was used to detect potential predictors of spasm-freedom after surgical decompression of the facial nerve in elderly patients that received ≤8 and >8 botulinum toxin treatments for hemifacial spasm before surgery. Age, sex, side, preoperative symptom duration, and preoperative botulinum toxin treatment were assessed as potential predictors of spasm-freedom at last follow-up., Results: Of 76 elderly patients with hemifacial spasm treated with botulinum toxin and microvascular decompression, with at least 2-years of follow-up (median, 44.5 months), 84.2% were spasm-free at last follow-up. Age (P = 0.38), sex (P = 0.59), side (P = 0.15), preoperative symptom duration (P = 0.7), and number of preoperative botulinum toxin treatments (P = 0.3) were not predictors of long-term spasm-freedom. Permanent ipsilateral hearing loss was the most frequent complication (3.9%)., Conclusion: This study provides evidence that elderly patients can undergo botulinum toxin treatment for hemifacial spasm without compromising their likelihood of achieving spasm-freedom with future surgical decompression. Therefore, surgical decompression of the facial nerve is an effective therapy for elderly patients with hemifacial spasm refractory to botulinum toxin., (© 2024 International Parkinson and Movement Disorder Society.)

Objective: Tumors may be responsible for up to 5% of trigeminal neuralgia cases. Predictors of long-term pain relief after surgical resection of various cerebellopontine angle tumor types are not well understood. Previous studies found that size and extent of resection predict long-term pain status, although resection of tumor involving the trigeminal ganglion may be associated with high morbidity. This study evaluated predictors of TN pain freedom after resection of a nonacoustic CPA tumor, with avoidance of any portion involving the TG., Methods: In a retrospective cohort study, we evaluated clinical outcomes and complications after surgical resection of nonacoustic CPA tumors with purposeful avoidance of the TG causing trigeminal neuralgia. The primary outcome was pain-freedom. We performed logistic regression analyses to examine the relationship between pain-freedom at last follow-up and age, side of symptoms, preoperative symptom duration, tumor diameter, tumor type, and concurrent neurovascular compression (NVC)., Results: Of 18 patients with nonacoustic CPA tumors causing TN treated with surgical resection, 83.3% were pain-free at last follow-up (mean 44.6 months). Age (P = 0.12), side (P = 0.41), preoperative symptom duration (P = 0.85), tumor diameter (P = 0.29), tumor type (P = 0.37), and NVC presence (P = 0.075) were not associated with long-term pain freedom., Conclusions: This study provides additional evidence that various tumor types causing TN may safely undergo surgical resection and decompression of the trigeminal nerve to treat TN. This study presents a cohort of patients that underwent resection of a nonacoustic CPA tumor, with purposeful avoidance of the TG to minimize complications, demonstrating high rates of long-term pain freedom., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background and Objectives: Classical trigeminal neuralgia (cTN) is a painful disease. Microvascular decompression (MVD) provides immediate and durable relief in many patients. A variety of positive and negative prognostic biomarkers for MVD have been identified. The sagittal angle of the trigeminal nerve at the porus trigeminus (SATNaPT) is an MRI biomarker that can identify a subset of patients with cTN whose trigeminal nerve anatomy is different from normal controls. The purpose of this case-control study was to determine whether an abnormally hyperacute SATNaPT is a negative prognostic biomarker in patients with cTN undergoing MVD., Methods: Preoperative MRIs from 300 patients with cTN who underwent MVD were analyzed to identify patients with a hyperacute SATNaPT (defined as less than 3 SDs below the mean). The rate of surgical success (pain-free after at least 12 months) was compared between patients with a hyperacute SATNaPT and all other patients., Results: Patients without a hyperacute SATNaPT had an 82% likelihood of surgical success, whereas patients with a hyperacute SATNaPT had a 58% likelihood of surgical success ( P < .05). Patients with a hyperacute SATNaPT who also had no evidence of vascular compression on preoperative MRI had an even lower likelihood of success (29%, P < .05)., Conclusion: In patients with cTN being considered for MVD, a hyperacute SATNaPT is a negative prognostic biomarker that predicts a higher likelihood of surgical failure. Patients with a hyperacute SATNaPT, particularly those without MRI evidence of vascular compression, may benefit from other surgical treatments or a modification of MVD to adequately address the underlying cause of cTN., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Background: Developmental venous anomaly (DVA) is a rare cause of hemifacial spasm (HFS). The treatment of HFS caused by a DVA varies in the literature and includes medication management, botulinum toxin injections, and microvascular decompression (MVD)., Observations: A 64-year-old woman presented with right-sided HFS. Preoperative magnetic resonance imaging showed a DVA in the right inferior pons, with an enlarged segment compressing the facial nerve at its root detachment point prior to drainage into the superior petrosal sinus. MVD was performed, and the facial nerve was decompressed without sacrifice of the vein. Immediately following the procedure, the patient had significantly reduced spasms. The patient became spasm-free 3 months after MVD and maintained spasm freedom for 3 months. Six months after MVD, the patient had a partial return of spasms. At 8 months, the patient continued to have reduced and intermittent spasms in the right orbicularis oculi muscle., Lessons: MVD for HFS caused by a DVA is a safe procedure and can be effective at reducing spasm frequency and severity.

Individuals with osteogenesis imperfecta develop pathologic bone due to genetic defects in collagen synthesis. These patients are prone to skull base abnormalities with resultant lower cranial nerve deficits, most common of which is trigeminal neuralgia. Typically, such patients are managed medically, and surgical options are not well explored for those patients, who become refractory to medication management. While microvascular decompression is often recommended for patients with classical trigeminal neuralgia, neurovascular compression by MRI, and normal skull base anatomy, ablative procedures have been described for patients with trigeminal neuralgia and osteogenesis imperfecta. MVD via a retrosigmoid approach has not been described in a patient with trigeminal neuralgia and skull base abnormalities secondary to osteogenesis imperfecta. A 23-year-old man with osteogenesis imperfecta was referred with right-sided classical trigeminal neuralgia. His trigeminal pain had become refractory to a number of medications. High-resolution MRI demonstrated compression of the trigeminal nerve by the superior cerebellar artery. Microvascular decompression of the trigeminal nerve via a retrosigmoid craniectomy was performed, and he remains pain-free 6 months after surgery. Microvascular decompression of the trigeminal nerve through a retrosigmoid approach can be an effective surgical treatment for young patients with trigeminal neuralgia secondary to osteogenesis imperfecta.

Background and Purpose: Patients with idiopathic trigeminal neuralgia (TN) with absent arterial contact or venous contact only and classic TN with morphological changes of the trigeminal nerve secondary to venous compression are not routinely recommended microvascular decompression at our institution. In patients with these anatomical subtypes of TN, limited data exists describing the outcomes of percutaneous glycerol rhizolysis (PGR) of the trigeminal ganglion (TG)., Methods: We performed a retrospective single-center cohort study and analyzed outcomes and complications after PGR of the TG. Clinical outcome after PGR of the TG was assessed via the Barrow Neurological Institute (BNI) Pain Scale., Results: Forty-five patients underwent a total of 66 PGRs of the TG. At short-term follow-up, 58 procedures (87.9%) resulted in a BNI score of I (i.e., freedom from pain without medication). At a median follow-up of 3.07 years, 18 procedures (27.3%) resulted in a BNI score of I, 12 procedures (18.1%) resulted in BNI score of IIIa, and 36 procedures (54.5%) resulted in a BNI score of IIIb-V. The median length of freedom from pain without medication was 1.5 years. Eighteen procedures (27.3%) caused hypesthesia and two (3.0%) caused paresthesias. There were no serious complications., Conclusion: In patients with these anatomical subtypes of TN there was a high rate of short-term pain relief for the first 1-2 years and thereafter a large proportion of patients experienced pain relapse. In this patient group, PGR of the TG represents a safe procedure that is efficacious in the short term., (© 2023 European Academy of Neurology.)

Spontaneous cerebellar hemorrhage (scICH) is a subset of intracerebral hemorrhage accounting for 5-10% of all cases. Despite potential advantages, minimally invasive surgical evacuation of scICH may be an underutilized strategy when compared to unilateral or bilateral large suboccipital craniectomy or craniotomy, with or without duraplasty. We performed a retrospective single-center cohort study and a systematic literature review. Radiographic and clinical data were recorded and analyzed. Five consecutive patients with minimally invasive surgical evacuation of scICH were identified. Average hematoma size was 16.4 ± 3.0 cm 3 . Mean Glasgow coma score (GCS) prior to surgery was 11.6 ± 3.0 with improvement to 14.6 ± 0.4 postoperatively. Mean hematoma evacuation was 92.6 ± 0.6% as confirmed by postoperative computed tomography (CT) imaging. All patients achieved a modified Rankin Scale (mRS) score of 0 or 1 with an average follow-up time of 31 ± 22 months. Mean length of hospital stay was 8.8 ± 3.0 days. No patients experienced significant complications or required reoperation. Systematic review revealed similar results for minimally invasive evacuation of scICH when reporting disaggregated outcomes. A review of recent studies utilizing large unilateral or bilateral suboccipital craniectomy or craniotomy, with or without duraplasty, revealed higher morbidity and mortality rates than minimally invasive surgical evacuation of scICH. Minimally invasive evacuation of scICH is safe and effective. Near complete evacuation of hematoma can be achieved with lower morbidity and mortality than large suboccipital craniectomy or craniotomy. A multi-center, prospective, and rigorous trial comparing the two strategies for evacuation of scICH is warranted., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background  Stereotactic radiosurgical rhizolysis of the trigeminal nerve is an established modality increasingly employed to alleviate the symptoms of refractory trigeminal neuralgia. This study analyzes the academic impact of the top 100 cited articles on the radiosurgical management of trigeminal neuralgia. Methods  The Scopus database was searched for articles containing "radiosurgery" and one or more of "trigeminal neuralgia," "trigeminus neuralgia," and "tic douloureux." The top 100 articles written in English were arranged in descending order by citation count. Documents were evaluated for authors, publication year, journal and impact factor, total citations, nationality, study type, radiosurgical modality, and the affiliated institution. Quantitative and qualitative analyses were performed on the data. Results  The most cited articles were published between 1971 and 2019. The average citation per year was 4.3. The most targeted anatomic area was the "root entry zone" or proximal portion of the cisternal segment of the trigeminal nerve. The most utilized modality was Gamma Knife radiosurgery. The country with the highest number of publications was the United States. Thirty-six percent of the articles were published in the Journal of Neurosurgery . Lunsford, Kondziolka, Flickinger, and Régis, respectively, were the most frequently listed co-authors. The most prolific institute was the University of Pittsburgh Medical Center. Conclusion  Stereotactic radiosurgery is an important modality in the management of medically or surgically refractory trigeminal neuralgia. This analysis assesses its contributions over the past five decades to identify trends in treatment practices for neurosurgeons and to highlight areas where further study is needed., Competing Interests: Conflict of Interest None declared., (Asian Congress of Neurological Surgeons. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. ( https://creativecommons.org/licenses/by-nc-nd/4.0/ ).)

Background: The lateral supraorbital approach (LSO) provides an optimal access corridor for various skull bases lesions, including olfactory groove meningiomas (OGMs). The aim of this study is to describe the authors' experience with the management of large and giant OGMs utilizing the LSO approach and describe the technical nuances of the procedure., Methods: A retrospective review of seven patients with large and giant OGMs managed with the LSO approach between 2013 and 2019 was performed. Radiographic and clinical data were recorded and analyzed., Results: Seven patients with large and giant OGMs underwent surgical resection via the LSO approach. Six patients were female, with a median age of 56 years. Patients commonly presented with altered mentation, anosmia, and headaches. The average tumor volume was 120.6 ± 64.7 cm 3 with five cases of vascular encasement. Simpson grade II resection was achieved in four patients while Simpson grade IV resection was achieved in three patients. The median length of stay was 2.0 days. The median preoperative Karnofsky Performance Scale (KPS) score was 70, improving to 100 at last postoperative follow-up visit. Two complications were encountered in the form of postoperative cerebrospinal fluid leak in one patient and a transient diplopia in another patient. Tumor recurrence/progression was identified in two patients during a median follow-up time of 65.5 months. Both cases have been managed with adjuvant radiosurgery., Conclusion: The LSO approach is a safe and effective minimally invasive transcranial corridor for the management of OGMs that should be part of the armamentarium of skull base neurosurgeons.

Pain is an experience of a subjective nature, interpreted in a personal way and according to an extensive palette of factors unique to each individual. Orofacial pain can be acute or chronic and it is usually the main reason for the patient to seek dental care. Pain perception varies widely among individuals. This variability is considered a mosaic of factors, which include biopsychosocial factors and genetic factors. Understanding these differences can be extremely beneficial for pain management in a personalized and more efficient way. We performed association studies to investigate phenotypes associated with genetic markers in pain-related genes in two groups of patients who received more or less anesthesia during dental treatment. The study group was comprised of 1289 individuals participating in the Dental Registry and DNA Repository Project (DRDR) of the University of Pittsburgh, with 900 participants in the group that received the most anesthesia and 389 constituting the comparison group that received less anesthesia. We tested 58 phenotypes and genotypic data of seven SNPs in genes that are associated with pain perception, pain modulation and response to drugs used in pain treatment: COMT (rs4818 and rs6269), GCH1 (rs3783641), DRD2 (rs6276), OPRM1 (rs1799971), SCN9A (rs6746030) and SCN10A (rs6795970). The analysis revealed a protective effect of rs1799971 on asthma in the total sample. rs3783641 was associated with salivary secretion disorders in females who received more anesthesia. rs1799971 was also associated with periodontitis in Whites who received less anesthesia. rs4818 was associated with disease and other tongue conditions in the group composed of Blacks who received less anesthesia. In conclusion, our study implicated variants in pain-related genes in asthma and oral phenotypes., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2022 Lisboa et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: After microvascular decompression (MVD) for hemifacial spasm (HFS), a minority of patients realize little to no relief of spasms. In some patients, the absence of relief of spasms results from incomplete or inadequate decompression of vascular compression of the facial nerve, and these patients represent excellent candidates for repeat MVD. However, in other patients, repeat MVD is not appropriate because adequate decompression and resolution of neurovascular compression, as determined by postoperative high-resolution MRI, was achieved with the initial operation., Objective: To present a cohort of patients with a history of HFS refractory to MVD, with no evidence of neurovascular compression on postoperative MRI, who underwent facial nerve massage (FNM) in the posterior fossa in an attempt to relieve spasms., Methods: Thirteen patients with a history of incomplete relief of spasms after technically adequate MVD surgery for hemifacial spasm underwent FNM. Immediate and long-term degree of spasm relief and complications after FNM were documented through in-person or telemedicine interview., Results: At follow-up after FNM, 7 of 12 patients (58.3%) reported complete spasm relief (grade I), 2 of 12 patients (16.7%) reported &gt;75% spasm relief (grade II), 0 patient (0%) reported &gt;50% spasm relief (grade III), 3 of 12 (25.0%) patients reported &lt;50% spasm relief (grade IV), and 1 patient was lost to follow-up. One patient experienced a delayed facial paresis, and another patient experienced high-frequency hearing loss., Conclusion: After FNM, durable and, at least, partial relief of spasms with a relatively low complication rate was observed in most patients with HFS with incomplete relief of spasms after technically adequate prior MVD., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Objective: Lumbar spondylolysis occurs in 5%-8% of adults. This study aimed to report clinical and radiographic outcomes of direct pars repair in adults with lumbar spondylolysis., Methods: We conducted a retrospective review of all patients treated for lumbar spondylolysis via open fracture reduction and direct pars repair with cannulated screws using a lag technique. Demographics, clinical presentation, perioperative and intraoperative imaging, and postoperative data were collected. We subsequently performed a systematic review to describe radiographic and clinical outcomes following direct pars repair., Results: Three patients were identified (mean age 40.3 years; range, 21-72 years; 2 male). All patients had bilateral L5 pars fractures treated via open, direct repair with cannulated screws. There were no intraoperative complications. Length of stay was <24 hours for each patient. All patients reported back/radicular symptom relief and returned to full-time manual labor by latest follow-up. Noncontrast lumbar computed tomography performed 14-20 months postoperatively confirmed that all patients had good bilateral screw placement without fracture. Two patients (21 and 28 years old at surgery) had evidence of fusion across fracture sites, while 1 patient exhibited radiolucency around the screws and no progression of spondylolisthesis. Additionally, we reviewed 8210 articles and included 15 in a systematic review of direct pars repair. Fusion rates were 67%-100%, with improved average Oswestry Disability Index and visual analog scale back pain scores by latest follow-up., Conclusions: Lumbar spondylolysis treatment with open fracture reduction and direct pars repair with cannulated screws in adults is safe and may result in mechanical back/radicular pain relief, even in the absence of radiographic fusion., (Copyright © 2022. Published by Elsevier Inc.)

Different peripheral nerve injuries cause neuropathic pain through distinct mechanisms. Even the site of injury may impact underlying mechanisms, as indicated by the clinical finding that the antiseizure drug carbamazepine (CBZ) relieves pain because of compression injuries of trigeminal but not somatic nerves. We leveraged this observation in the present study hypothesizing that because CBZ blocks voltage-gated sodium channels (VGSCs), its therapeutic selectivity reflects differences between trigeminal and somatic nerves with respect to injury-induced changes in VGSCs. CBZ diminished ongoing and evoked pain behavior in rats with chronic constriction injury (CCI) to the infraorbital nerve (ION) but had minimal effect in rats with sciatic nerve CCI. This difference in behavior was associated with a selective increase in the potency of CBZ-induced inhibition of compound action potentials in the ION, an effect mirrored in human trigeminal versus somatic nerves. The increase in potency was associated with a selective increase in the efficacy of the Na V 1.1 channel blocker ICA-121431 and Na V 1.1 protein in the ION, but no change in Na V 1.1 mRNA in trigeminal ganglia. Importantly, local ICA-121431 administration reversed ION CCI-induced hypersensitivity. Our results suggest a novel therapeutic target for the treatment of trigeminal neuropathic pain. SIGNIFICANCE STATEMENT This study is based on evidence of differences in pain and its treatment depending on whether the pain is above (trigeminal) or below (somatic) the neck, as well as evidence that voltage-gated sodium channels (VGSCs) may contribute to these differences. The focus of the present study was on channels underlying action potential propagation in peripheral nerves. There were differences between somatic and trigeminal nerves in VGSC subtypes underlying action potential propagation both in the absence and presence of injury. Importantly, because the local block of Na V 1.1 in the trigeminal nerve reverses nerve injury-induced mechanical hypersensitivity, the selective upregulation of Na V 1.1 in trigeminal nerves suggests a novel therapeutic target for the treatment of pain associated with trigeminal nerve injury., (Copyright © 2021 the authors.)

Identify preoperative imaging findings in hemifacial spasm patients that predict the post-surgical success following microvascular decompression. This is a retrospective study of patients who were diagnosed with hemifacial spasm, had a dedicated cranial nerve MRI, and underwent microvascular decompression for hemifacial spasm. Bilateral facial nerves were interrogated for neurovascular compression. If neurovascular compression was identified, we recorded whether the offending vessel was an artery, a vein or both. The location of the neurovascular compression (proximal nerve versus distal nerve) was noted. The severity of the neurovascular compression was categorized as contact versus deformity of the nerve. Patients were contacted to determine their post-operative spasm status. The relationships between imaging findings and post-surgical outcome were assessed by Chi-square tests, and odds ratios were calculated to quantify the degree of association. The study included 212 patients. Upon follow up, 192 patients were spasm free (90.57%). Imaging findings on the symptomatic side were as follows: arterial neurovascular compression was seen in 207 patients (97.64%), venous only neurovascular compression in two patients (0.94%), and no neurovascular compression in three patients (1.42%). Arterial neurovascular compression along the proximal, susceptible segment of the nerve was observed in 202 patients (95.28%); deformity was observed more commonly than contact alone. Arterial neurovascular compression along the distal segment only of the nerve was observed in five patients (2.36%). In patients with arterial neurovascular compression of the proximal and distal portions of the nerve, 93.07% and 60.0% of patients were spasm-free respectively. If venous neurovascular compression only was observed on imaging, 0% of patients were spasm-free. Patients with arterial neurovascular compression of the susceptible segment are much more likely to be spasm free than patients without this imaging finding, [odds ratio 20.14 (CI 5.08, 79.81), P -value <0.0001]. When comparing the two groups of arterial neurovascular compression (deformity versus contact), no statistically significant difference in outcomes was observed. In patients with hemifacial spasm undergoing microvascular decompression, imaging findings do predict surgical outcome. Patients with arterial neurovascular compression of the proximal, susceptible portion of the nerve are much more likely to be spasm free after surgery than those without this imaging finding. The imaging findings inform the risk benefit analysis and discussion with patients before they undergo microvascular decompression for hemifacial spasm., (© The Author(s) (2021). Published by Oxford University Press on behalf of the Guarantors of Brain.)

Hemifacial spasm is typically caused by vascular compression of the proximal intracranial facial nerve. Although the prevalence of neurovascular compression has been investigated in a cohort of patients with classical trigeminal neuralgia, the prevalence and severity of neurovascular compression has not been well characterized in patients with hemifacial spasm. We aimed to investigate whether presence and severity of neurovascular compression are correlated to the symptomatic side in patients with hemifacial spasm. All patients in our study were evaluated by a physician who specializes in the management of cranial nerve disorders. Once hemifacial spasm was diagnosed on physical exam, the patient underwent a dedicated cranial nerve protocol magnetic resonance imaging study on a 3 T scanner. Exams were retrospectively reviewed by a neuroradiologist blinded to the symptomatic side. The presence, severity, vessel type, and location of neurovascular compression along the facial nerve was recorded. Neurovascular compression was graded as contact alone (vessel touching the facial nerve) versus deformity (indentation or deviation of the nerve by the culprit vessel). A total of 330 patients with hemifacial spasm were included. The majority (232) were female while the minority (98) were male. The average age was 55.7 years. Neurovascular compression (arterial) was identified on both the symptomatic (97.88%) and asymptomatic sides (38.79%) frequently. Neurovascular compression from an artery along the susceptible/proximal portion of the nerve was much more common on the symptomatic side (96.36%) than on the asymptomatic side (12.73%), odds ratio = 93.00, P < 0.0001. When we assessed severity of arterial compression, the more severe form of neurovascular compression, deformity, was noted on the symptomatic side (70.3%) much more frequently than on the asymptomatic side (1.82%) (odds ratio = 114.00 P < 0.0001). We conclude that neurovascular compression that results in deformity of the susceptible portion of the facial nerve is highly associated with the symptomatic side in hemifacial spasm., (© The Author(s) (2021). Published by Oxford University Press on behalf of the Guarantors of Brain.)

We sought to evaluate feasibility and cost-reduction potential of a pilot screening program involving neurosurgeon tele-consultation for inter-facility transfer decisions in TBI patients with GCS 14-15 and abnormal CT head at a community hospital. The authors performed a retrospective comparative analysis of two patient cohorts during the pilot at a large hospital system from 2015 to 2017. In "screened" patients (n = 85), images and examination were reviewed remotely by a neurosurgeon who made recommendations regarding transfer to a level 1 trauma center. In the "unscreened" group (n = 39), all patients were transferred. Baseline patient characteristics, outcomes, and costs were reviewed. Patient demographics were similar between cohorts. Traumatic subarachnoid hemorrhage was more common in screened patients (29.4% vs 12.8%, P = 0.02). The presence of midline shift >5 mm was comparable between groups. Among screened patients, 5 were transferred (5.8%) and one required evacuation of chronic subdural hematoma. In unscreened patients, 7 required evacuation of subdural hematoma. None of the screened patients who were not transferred deteriorated. Screened patients had significantly reduced average total cost compared to unscreened patients ($2,003 vs. $4,482, P = 0.03) despite similar lengths of stay (2.6 vs. 2.7 days, P = 0.85). In non-surgical patients, costs were less in the screened group ($2,025 vs. $2,939), although statistically insignificant (P = 0.38). In this pilot study, remote review of images and examination by a neurosurgeon was feasible to avoid unnecessary transfer of patients with traumatic intracranial hemorrhage and GCS 14-15. The true potential in cost-reduction will be realized in system-wide large-scale implementation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Introduction: Medical student involvement opportunities and educational experiences with surgical residents during medical school have been shown to increase the chance of students deciding to specialize in surgical specialties. This study aims to determine the effect of a neurosurgery elective during the second preclinical year on student interest and opinion of neurosurgery., Methods: Thirty-nine students completed opinion-based surveys and factual knowledge quizzes during a neurosurgical elective course over 3 iterations, which included lecture and skills lab instruction. Pre- and post-course surveys used the Likert scale, with a score of 1 corresponding to the most negative opinion and a score of 10 corresponding to the most positive opinion, in order to measure various aspects including interest in neurological surgery, understanding of the field, and perception of female inclusion in the field. Weekly pre- and post-lecture quizzes assessed practical knowledge of neurosurgical topics., Results: A higher percentage of students rated neurosurgery highly as a career possibility (⩾8/10 interest level) post-course (58.6%) compared to pre-course (45.7%). Post-course, students reported a significantly increased mean understanding of neurosurgery on the Likert scale compared to pre-course (6.1 ± 1.7 vs 4.4 ± 2.0; P  = .001). Knowledge based-content assessment revealed a significant increase in overall correct answers after lectures (mean pre  = 3.85, mean post  = 5.05, P  = .001). Inclusion of female instructors in the second and third iteration of the course resulted in a significant increase in students' perception of female inclusion in the field of neurosurgery (7.6 compared to 5.6, P  = .01)., Conclusions: Early exposure to subspecialties may assist in making important career decisions. The implementation of this neurosurgical elective improved medical students' perception of the field and enhanced knowledge of the lectures and procedures. This study can be used as a framework for implementation of this curriculum at other institutions., Competing Interests: Declaration of conflicting interests:The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2020.)

Background: Microvascular decompression (MVD) is the surgical treatment of choice for hemifacial spasm (HFS). During MVD, monitoring of the abnormal lateral spread response (LSR), an evoked response to facial nerve stimulation, has been traditionally used to monitor adequacy of cranial nerve (CN) VII decompression., Objective: To assess the utility of LSR monitoring in predicting spasm-free status after MVD postoperatively., Methods: We searched PubMed, Web of Science, and Embase for relevant publications. We included studies reporting on intraoperative LSR monitoring during MVD for HFS and spasm-free status following the procedure. Sensitivity of LSR, specificity, diagnostic odds ratio, and positive predictive value were calculated., Results: From 148 studies, 26 studies with 7479 patients were ultimately included in this meta-analysis. The final intraoperative LSR status predicted the clinical outcome of MVD with the following specificities and sensitivities: 89% (0.83- 0.93) and 40% (0.30- 0.51) at discharge, 90% (0.84-0.94) and 41% (0.29-0.53) at 3 mo, 89% (0.83-0.93) and 40% (0.30-0.51) at 1 yr. When LSR persisted after MVD, the probability (95% CI) for HFS persistence was 47.8% (0.33-0.63) at discharge, 40.8% (0.23-0.61) at 3 mo, and 24.4% (0.13-0.41) at 1 yr. However, when LSR resolved, the probability for HFS persistence was 7.3% at discharge, 4.2% at 3 mo, and 4.0% at 1 yr., Conclusion: Intraoperative LSR monitoring has high specificity but modest sensitivity in predicting the spasm-free status following MVD. Persistence of LSR carries high risk for immediate and long-term facial spasm persistence. Therefore, adequacy of decompression should be thoroughly investigated before closing in cases where intraoperative LSR persists., (Copyright © 2020 by the Congress of Neurological Surgeons.)

Trigeminal neuralgia (TN) is a common, debilitating neuropathic face pain syndrome often resistant to therapy. The familial clustering of TN cases suggests that genetic factors play a role in disease pathogenesis. However, no unbiased, large-scale genomic study of TN has been performed to date. Analysis of 290 whole exome-sequenced TN probands, including 20 multiplex kindreds and 70 parent-offspring trios, revealed enrichment of rare, damaging variants in GABA receptor-binding genes in cases. Mice engineered with a TN-associated de novo mutation (p.Cys188Trp) in the GABA A receptor Cl - channel γ-1 subunit ( GABRG1 ) exhibited trigeminal mechanical allodynia and face pain behavior. Other TN probands harbored rare damaging variants in Na + and Ca + channels, including a significant variant burden in the α-1H subunit of the voltage-gated Ca 2+ channel Ca v 3.2 ( CACNA1H ). These results provide exome-level insight into TN and implicate genetically encoded impairment of GABA signaling and neuronal ion transport in TN pathogenesis., Competing Interests: The authors declare no competing interests., (© 2020 The Authors.)

Background: Microvascular decompression (MVD) can be an effective intervention for trigeminal neuralgia (TN); however, an optimal system for patient selection and surgical outcome prediction has not been defined., Objective: To develop and validate a preoperative TN grading system for the prediction of long-term pain relief after MVD., Methods: This retrospective cohort study included consecutive patients suffering unilateral TN who underwent MVD with >18-mo follow-up. A grading system was formulated using 3 previously validated preoperative characteristics. The primary end-point was long-term, pain-free status without use of medication. Ability to predict pain-free status was analyzed by multiple regression and assessed by area under the receiver operating characteristic curve (AUC). Clinical utility to predict MVD success and reduce unnecessary surgeries was assessed by decision-curve analysis., Results: Of 208 patients analyzed, 73% were pain-free without medication at >18-mo follow-up. Pain-free status was predicted by classical TN type, positive response to carbamazepine and/or oxcarbazepine, and presence and nature of neurovascular compression demonstrated on MRI (all P < .01). The TN grading system demonstrated good discriminatory ability for prediction of pain-free status (AUC 0.85, 95% CI 0.80-0.91). Decision-curve analysis demonstrated a net reduction of 20 cases likely to be unsuccessful per 100 patients evaluated with this grading system above a decision threshold of 80%., Conclusion: This TN grading system reliably predicts long-term pain-free status without medications following MVD. The use of the TN grading system as part of a comprehensive work-up may reduce the number of unsuccessful operations., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Introduction  Facial weakness can result from surgical manipulation of the facial nerve. Intraoperative neuromonitoring reduces functional impairment but no clear guidelines exist regarding interpretation of intraoperative electrophysiological results. Most studies describe subjects with facial nerves encumbered by tumors or those with various grades of facial nerve weakness. We sought to obtain the neurophysiological parameters and stimulation threshold following intraoperative facial nerve triggered electromyography (t-EMG) stimulation during microvascular decompression for trigeminal neuralgia to characterize the response of normal facial nerves via t-EMG. Methods  Facial nerve t-EMG stimulation was performed in seven patients undergoing microvascular decompression for trigeminal neuralgia. Using constant current stimulation, single stimulation pulses of 0.025 to 0.2 mA intensity were applied to the proximal facial nerve. Compound muscle action potentials, duration to onset, and termination of t-EMG responses were recorded for the orbicularis oculi and mentalis muscles. Patients were evaluated for facial weakness following the surgical procedure. Results  Quantifiable t-EMG responses were generated in response to all tested stimulation currents of 0.025, 0.05, 0.1, and 0.2 mA in both muscles, indicating effective nerve conduction. No patients developed facial weakness postoperatively. Conclusions  The presence of t-EMG amplitudes in response to 0.025 mA suggests that facial nerve conduction can take place at lower stimulation intensities than previously reported in patients with tumor burden. Proximal facial nerve stimulation that yields responses with thresholds less than 0.05 mA may be a preferred reference baseline for surgical procedures within the cerebellopontine angle to prevent iatrogenic injury., Competing Interests: Competing Interests Statement The authors have no personal or institutional interest with regards to the authorship and/or publication of this manuscript., (© Thieme Medical Publishers.)

Objective: The aim of this study was to identify preoperative imaging predictors of surgical success in patients with classic trigeminal neuralgia (cTN) undergoing microvascular decompression (MVD) via retrospective multivariate regression analysis., Methods: All included patients met criteria for cTN and underwent preoperative MRI prior to MVD. MR images were blindly graded regarding the presence and severity (i.e., mild or severe) of neurovascular compression (NVC). All patients were contacted by telephone to determine their postoperative pain status., Results: A total of 79 patients were included in this study. Sixty-two patients (78.5%) were pain-free without medication following MVD. The following findings were more commonly observed with the symptomatic nerve when compared to the contralateral asymptomatic nerve: NVC (any form), arterial compression alone, NVC along the proximal trigeminal nerve, and severe NVC (p values < 0.0001). The only imaging variable that was a statistically significant predictor of being pain-free without medication following MVD was severe NVC. Patients with severe NVC were 6.36 times more likely to be pain-free following MVD compared to those without severe NVC (p = 0.007)., Conclusions: In patients with cTN undergoing MVD, severe NVC on preoperative MRI is a strong predictor of an excellent surgical outcome.

Background and Objective: Both microvascular decompression (MVD) and Gamma Knife radiosurgery (GKRS) are time-tested treatment modalities for trigeminal neuralgia (TN). There is little evidence in the literature studying these modalities head to head in a cost-effectiveness comparison., Objective: To evaluate the cost-effectiveness of MVD compared with GKRS for treating patients with TN., Methods: We developed a Markov cost-effectiveness model for the U.S. health care system to account for all costs related to MVD and GKRS as treatment modalities for TN, from the health care system perspective, over a patient lifetime horizon. A base case was estimated using data from previous studies, from our own GKRS experience, and from a current data analysis of patients undergoing MVD. We derived model inputs, including health care costs, survival, and utility estimates, from the literature. We used age-specific, sex-specific, and race-specific mortality from national registries. Costs studied included those for MVD, for GKRS, for treating complications from either procedure, and for medications throughout patient lifetimes. We performed multiple 1-way, 2-way, and probabilistic sensitivity analyses to confirm the robustness of model assumptions and results. The incremental cost-effectiveness ratio (ICER), with a threshold of $50,000 per quality-adjusted life-year (QALY) gained, defined cost-effectiveness., Results: The base case had an ICER of $12,154 per QALY for MVD compared with GKRS. Probabilistic sensitivity (Monte Carlo) analysis showed that MVD was cost-effective in 70% of model iterations. GKRS was favored when the willingness to pay threshold was <$12,000 per QALY gained., Conclusions: In patients medically eligible for either procedure, we found MVD to be the most cost-effective modality to treat TN, primarily because of its reported greater durability. MVD remained the most cost-effective strategy across a broad range of model input values in sensitivity analyses., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: While high-resolution imaging is increasingly used in guiding decisions about surgical interventions for the treatment of trigeminal neuralgia, direct assessment of the extent of vascular contact of the trigeminal nerve is still considered the gold standard for the determination of whether nerve decompression is warranted., Objective: To compare intraoperative and magnetic resonance imaging (MRI) findings of the prevalence and severity of vascular compression of the trigeminal nerve in patients without classical trigeminal neuralgia., Methods: We prospectively recruited 27 patients without facial pain who were undergoing microvascular decompression for hemifacial spasm and had undergone high-resolution preoperative MRI. Neurovascular contact/compression (NVC/C) by artery or vein was assessed both intraoperatively and by MRI, and was stratified into 3 types: simple contact, compression (indentation of the surface of the nerve), and deformity (deviation or distortion of the nerve)., Results: Intraoperative evidence of NVC/C was detected in 23 patients. MRI evidence of NVC/C was detected in 18 patients, all of whom had intraoperative evidence of NVC/C. Thus, there were 5, or 28% more patients in whom NVC/C was detected intraoperatively than with MRI (Kappa = 0.52); contact was observed in 4 of these patients and compression in 1 patient. In patients where NVC/C was observed by both methods, there was agreement regarding the severity of contact/compression in 83% (15/18) of patients (Kappa = 0.47). No patients exhibited deformity of the nerve by imaging or intraoperatively., Conclusion: There was moderate agreement between imaging and operative findings with respect to both the presence and severity of NVC/C.

Objective: We have previously documented the utility of calcium phosphate cement cranioplasty following retromastoid craniectomy. In this study, we aimed to demonstrate its efficacy following a supraorbital approach for tumor resection., Methods: A retrospective analysis of a prospectively maintained database was conducted of eight patients (7 female, 1 male) with anterior cranial fossa meningiomas resected via a supraorbital approach followed by cranioplasty involving adjunctive or sole use of calcium phosphate cement., Results: Cranioplasty was achieved in all patients. No patient developed an incisional leak. The cohort had a mean follow-up of approximately 3.1 months (range: 0.5-7 months) in which time no further complications were noted. No patients developed post-surgical infections., Conclusion: In our experience, a low incidence of infection or CSF leaks has been noted after the use of calcium phosphate cement retromastoid cranioplasty. Extending this technique to supraorbital craniotomies may minimize incisional CSF leak.

Microsurgical procedures, such as petroclival meningioma resection, require careful surgical actions in order to remove tumor tissue, while avoiding brain and vessel damaging. Such procedures are currently performed under microscope magnification. Robotic tools are emerging in order to filter surgeons' unintended movements and prevent tools from entering forbidden regions such as vascular structures. The present work investigates the use of a handheld robotic tool (Micron) to automate vessel avoidance in microsurgery. In particular, we focused on vessel segmentation, implementing a deep-learning-based segmentation strategy in microscopy images, and its integration with a feature-based passive 3D reconstruction algorithm to obtain accurate and robust vessel position. We then implemented a virtual-fixture-based strategy to control the handheld robotic tool and perform vessel avoidance. Clay vascular phantoms, lying on a background obtained from microscopy images recorded during petroclival meningioma surgery, were used for testing the segmentation and control algorithms. When testing the segmentation algorithm on 100 different phantom images, a median Dice similarity coefficient equal to 0.96 was achieved. A set of 25 Micron trials of 80 s in duration, each involving the interaction of Micron with a different vascular phantom, were recorded, with a safety distance equal to 2 mm, which was comparable to the median vessel diameter. Micron's tip entered the forbidden region 24% of the time when the control algorithm was active. However, the median penetration depth was 16.9 μm, which was two orders of magnitude lower than median vessel diameter. Results suggest the system can assist surgeons in performing safe vessel avoidance during neurosurgical procedures.

Background and Purpose: Glossopharyngeal neuralgia causes extreme paroxysmal pain in the posterior pharynx, tonsillar region, base of tongue, or deep ear, that is, the distribution of the glossopharyngeal nerve. Some cases of glossopharyngeal neuralgia are associated with neurovascular conflict, usually by the posterior inferior cerebellar artery. Such symptomatic compression occurs only in proximal, centrally myelinated portions of the glossopharyngeal nerve near the brainstem. Microvascular decompression provides effective and durable pain relief for properly selected patients with medically refractory glossopharyngeal neuralgia. The purpose of this study is to describe a tailored MRI evaluation of neurovascular conflict in glossopharyngeal neuralgia to improve candidate selection for microvascular decompression., Methods: Our team developed a glossopharyngeal neuralgia imaging and evaluation protocol including a grading system for neurovascular conflict of the glossopharyngeal nerve and applied it to evaluate candidates for microvascular decompression., Results: Our team grades neurovascular conflict as "contact" (vessel touching nerve without intervening cerebrospinal fluid) versus "deformation" (deviation or distortion of nerve from its normal course by the offending vessel). MRIs of patients with glossopharyngeal neuralgia demonstrate proximal neurovascular conflict. Postoperative MRI demonstrates separation of the glossopharyngeal nerve from the offending vessel., Conclusion: A tailored glossopharyngeal neuralgia imaging evaluation protocol is presented. We believe this approach has helped improve microvascular decompression outcomes and reduce unnecessary procedures at our institution. Further research may elucidate whether clinical and imaging features, including neurovascular conflict severity, predict surgical outcome for glossopharyngeal neuralgia., (© 2018 by the American Society of Neuroimaging.)

OBJECTIVE Hemifacial spasm (HFS) is a movement disorder characterized by involuntary spasms of the facial muscles, and it can negatively impact quality of life (QOL). This retrospective study and systematic review with meta-analysis was conducted to investigate the QOL in patients with HFS following intervention with microvascular decompression (MVD) and botulinum toxin (BT). METHODS In the retrospective analysis, a QOL questionnaire was administered to all patients undergoing MVD performed by a single surgeon. The QOL questionnaire included unique questions developed based on the authors' experience with HFS patients in addition to the health-related QOL HFS-8 questionnaire. The authors also report on a systematic review of the English literature providing outcomes and complications in patients with HFS undergoing treatment with either MVD or BT. RESULTS Regarding the retrospective analysis, 242 of 331 patients completed the questionnaire. The mean score of the 10 QOL questions improved from 22.78 (SD 9.83) to 2.17 (SD 5.75) following MVD (p < 0.001). There was significant improvement across all subscales of the questionnaire between pre- and postoperative responses (p < 0.001). Regarding the systematic review, it is reported that approximately 90% of patients undergoing MVD for HFS experience a complete recovery from symptoms, whereas the mean peak improvement of symptoms following treatment with BT is 77%. Furthermore, patients undergoing MVD reported a greater improvement in the mean supplemental index of QOL as compared with patients receiving BT therapy. CONCLUSIONS Microvascular decompression offers a significant improvement in QOL in well-selected patients suffering from HFS, and may offer an increased benefit for QOL over BT injections.