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Abstract: For trigeminal neuralgia (TN), a major role of imaging is to identify the causes, but recent studies demonstrated structural and microstructural changes in the affected nerve. Moreover, an increasing number of studies have reported central nervous system involvement in TN. In this systematic review, recent quantitative magnetic resonance imaging (MRI) studies of the trigeminal nerve and the brain in patients with TN were compiled, organized, and discussed, particularly emphasizing the possible background mechanisms and the interpretation of the results. A systematic search of quantitative MRI studies of the trigeminal nerve and the brain in patients with TN was conducted using PubMed. We included the studies of the primary TN published during 2013 to 2023, conducted for the assessment of the structural and microstructural analysis of the trigeminal nerve, and the structural, diffusion, and functional MRI analysis of the brain. Quantitative MRI studies of the affected trigeminal nerves and the trigeminal pathway demonstrated structural/microstructural alterations and treatment-related changes, which differentiated responders from nonresponders. Quantitative analysis of the brain revealed changes in the brain areas associated with pain processing/modulation and emotional networks. Studies of the affected nerve demonstrated evidence of demyelination and axonal damage, compatible with pathological findings, and have shown its potential value as a tool to assess treatment outcomes. Quantitative MRI has also revealed the possibility of dynamic microstructural, structural, and functional neuronal plasticity of the brain. Further studies are needed to understand these complex mechanisms of neuronal plasticity and to achieve a consensus on the clinical use of quantitative MRI in TN., (Copyright © 2024 International Association for the Study of Pain.)

Purpose of Review: Trigeminal neuralgia (TN) is a highly heterogeneous condition with a wide choice of successful treatment options. However, differences between subtypes are poorly understood and it remains unknown which patients will respond to different treatments. This review aims to summarize the current state of the TN field and explore the problem of predicting surgical outcomes., Recent Findings: Attempts have been made to standardize classification, outcome reporting, and treatment guidelines. Identification of risk factors for poor surgical treatment outcomes has led to the development of prognostic scoring systems to predict outcomes and guide management. Advances in imaging techniques including diffusion tensor imaging show promise in better understanding the underlying pathophysiology and predicting surgical outcomes. Progress is hampered by lack of understanding of the pathophysiology in TN and differences between disease subtypes. Further work needs to be done to create accurate prediction tools for widespread use, including use of advanced imaging and computing tools, multicenter collaboration, and prospective validation., Competing Interests: Compliance with Ethical Standards. Ethical Approval: All reported studies/experiments with human or animal subjects performed by the authors have been previously published and complied with all applicable ethical standards (including the Helsinki declaration and its amendments, institutional/national research committee standards, and international/national/institutional guidelines). Conflict of Interest: The authors declare no competing interests. Human and Animal Rights and Informed Consent: This article does not contain any studies with human or animal subjects performed by any of the authors., (© 2025. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Objective: To explore the correlation between posterior fossa crowding and the occurrence of classical trigeminal neuralgia (TN)., Methods: A total of 60 patients diagnosed with classical TN and 60 age- and sex-matched healthy volunteers were included as a control group for a case-control study. All subjects underwent high-resolution 3D magnetic resonance imaging (MRI) examinations (including 3D-FIESTA and 3D-TOF MRA sequences). The original data were subjected to 3D reconstruction and measurement of posterior fossa volume (PFV) and hindbrain volume (HBV) using 3D-slicer software. The posterior fossa crowding index (PFCI) was calculated as HBV/PFV × 100%. Finally, data were analyzed using SPSS 22.0 statistical software., Results: The average PFCI in patients with TN was 85.0% ± 3.9%, compared to 82.7% ± 3.9% in the control group, with a significant statistical difference (P = 0.025). Female patients with TN had a more crowded posterior fossa than male patients (86.4% ± 3.8% vs. 83.4% ± 3.4%, P = 0.033). Multiple linear regression analysis showed that a higher PFCI was associated with being female (P = 0.022), younger age (P = - 0.003), and being a patient with TN (P = - 0.023)., Conclusion: Patients with PTN have a more crowded posterior fossa compared to the healthy control group. A higher PFCI is associated with being female, younger age, and being a patient with TN. Posterior fossa crowding may be a risk factor for neurovascular conflict (NVC), making it more likely to lead to the occurrence of TN., Competing Interests: Declarations. Ethics approval: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Consent for publication: All authors agreed with the content and that all gave explicit consent to submit and that they obtained consent from the responsible authorities at the institute/organization where the work has been carried out, before the work is submitted. Consent to participate: Due to the retrospective nature of this study, informed consent was not required. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

History: A 38-year-old previously healthy male patient presented with left-sided facial pain over the prior 5 weeks. He first noticed the pain while washing and applying pressure to his face. The pain was described as shock-like, sharp and shooting, and radiating along the left cheek and temple. It began as 1-2-second episodes occurring two to three times per day, sometimes spontaneously, progressing in severity and frequency over time. Mild progressive left facial weakness also developed a few weeks after initial symptoms. Physical examination demonstrated reproducible pain in the distribution of the maxillary division of the trigeminal nerve (V2), with normal motor and sensory function. A recent routine dental examination demonstrated healthy teeth and gums, and there was no history of dental procedures or trauma. The rest of the physical and neurologic examinations revealed no abnormalities. The patient was afebrile with normal vital signs. Findings of routine laboratory testing, including complete blood count, metabolic panel with electrolytes, kidney and liver function, and inflammatory markers such as C-reactive protein, were all within normal limits. Following the neurologic and otolaryngologic evaluations, imaging was recommended. The patient was also started on treatment with carbamazepine for trigeminal neuralgia, with modest improvement of symptoms. He initially underwent MRI of the temporal bones at an outside hospital. After subsequent referral to our hospital, follow-up concomitant MRI and CT (Figs 1-4) were performed approximately 3 months after the initial imaging.

The coincidence in a patient of Hemifacial Spasm and Trigeminal Neuralgia is not frequent. A case is presented with the objective of showing this association due to the abnormal activation of the Trigemino-Facial Reflex. A 55-year-old woman with an 8-year history of left-sided hemifacial spasm and typical trigeminal pain in the ipsilateral V1 and V2 territory. The physical examination shows spasms in the left hemiface, with reproduction of intense pain upon sensory stimulation of the skin on the forehead and upper dental arch. The MRI showed a vessel in intimate contact with the entrance area of ​​the left trigeminal nerve. A left retrosigmoid approach was performed. First, the entrance area of ​​the trigeminal nerve was accessed, finding a clear vascular conflict, which was isolated with Teflon. Then, the trajectory was changed and the exit zone of the facial nerve was accessed, and no type of vascular conflict was identified. The patient presented complete resolution of the Hemifacial Spasm and the associated trigeminal pain. The analysis of this case allows us to conclude that during microvascular decompression of the Facial Nerve, if frank proximal compression is not evident, the Trigeminofacial structural relationship must be taken into account, making it necessary to explore the Trigeminal Nerve., (Copyright © 2024. Published by Elsevier España, S.L.U.)

Background: Full-endoscopic microvascular decompression (fE-MVD) is an emerging treatment option for trigeminal neuralgia (TN). However, the risk factors associated with postoperative recurrence of TN after fE-MVD procedure remain controversial. The aim of the present study was to summarize the surgical technique of fE-MVD for the treatment of TN and to develop a predictive model for recurrence at 1 year postoperatively based on independent risk factors., Methods: A total of 124 consecutive patients with TN who underwent fE-MVD procedure were enrolled in this study between December 2008 and July 2022. Imaging data such as the area of cerebellopontine angle (CPA), the length of trigeminal cisternal segment, and the angle of trigeminal nerve (TGN) were measured from preoperative magnetic resonance imaging (MRI). Patients were randomly divided into a training set and a validation set according to the 7:3 ratio, respectively. Variables that were significant in the univariate logistic analyses were, subsequently, included in the multivariate logistic regression analyses in training set. Then, we developed a predictive nomogram for the 1-year recurrence of TN for patients who treated with fE-MVD., Results: All 124 patients experienced clinically significant pain relief (Barrow Neurology Institute (BNI) I-II) after fE-MVD. 124 patients had a follow-up time of more than 1 year, with 14 cases of recurrence. In the univariate analysis, the patients' responsible vessels of non-arterial, clinical features of atypical, and CPA area ratio (healthy/affected side) >1 were found to be significantly associated with recurrence of TN after fE-MVD. Multivariate logistic regression analyses result showed that the patients' responsible vessels of non-arterial (odds ratio (OR) = 21.067, 95% confidence interval (CI): 1.942-228.575), clinical features of atypical (OR = 9.027, 95% CI: 1.135-71.777), and CPA area ratio >1 (OR = 19.522, 95% CI: 2.906-131.160) were independent predictors of TN recurrence. Based on the independent predictive factors, we developed a predictive nomogram that predicts the 1-year recurrence of TN after fE-MVD. In the receiver operating characteristic (ROC) curve analysis, the area under the curve (AUC) of the nomograms for 1-year recurrence associated with optimal candidates prediction was 0.910 in the training set and 0.859 in the validation set., Conclusions: FE-MVD for the treatment of TN is a safe, reliable and effective procedure. Patients' responsible vessels of non-arterial, clinical features of atypical, and CPA area ratio (healthy/affected side) >1 are key risk factors associated with 1 year postoperative recurrence of TN after fE-MVD. Finally, we have developed a nomogram to predict the 1-year recurrence of TN for patients who treated with fE-MVD, which can be used to provide advice for patients after fE-MVD., Competing Interests: Declarations. Ethics approval and consent to participate: This single-centre, retrospective study was conducted in accordance with the tenets of the Helsinki Declaration of 1975 as revised in 2000. The study was approved by the Institutional Review Board of Beijing Shijitan Hospital, Capital Medical University (Approval No: sjtkyll-lx-2022-52). All patients or their legal guardians in this study authorized the release of their medical records and information. Consent for publication: Informed consent was obtained from all individual participants included in the study and alive at follow-up. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background: Trigeminal neuralgia (TN) is defined as spontaneous pain in the region of the trigeminal nerve that seriously affects a patient's quality of life. Percutaneous balloon compression of the trigeminal ganglion is a simple and reproducible surgical procedure that reduces the incidence of TN, but the postoperative outcome is poor in some patients, with it being ineffective or TN recurring., Objectives: To establish a machine learning-based clinical imaging nomogram to predict the recurrence of trigeminal neuralgia in patients treated with percutaneous balloon compression., Study Design: Retrospective study., Methods: The clinical data of 209 patients with TN treated with percutaneous balloon compression at Zhongnan Hospital of Wuhan University from January 2017 through August 2023 were retrospectively collected and randomized into training and validation cohorts. All imaging histologic morphological features were extracted from the intraoperative x-ray balloon region using 3D slicer software. The relationship among clinical factors, least absolute shrinkage and selection operator, and 4 machine learning predictions of the patient's TN prognosis were analyzed using a one-way analysis of clinical factors. A prediction model was constructed using receiver operating characteristics curve analysis. The performance of the clinical imaging histogram of patients' TN prognoses was evaluated using a receiver operating characteristics curve and decision curve analysis. The model was finally validated using a validation cohort and a receiver operating characteristics curve., Results: The training group included 149 patients; 16 morphology-related imaging histological features were extracted for analysis. After one-way logistic regression analysis, least absolute shrinkage and selection operator analysis incorporated original_shape_Elongation, original_shape_MajorAxisLength, original_shape_flatness morphology-related imaging histologic features, gender, and affected side to give a total of 6 predictors. The final results were obtained for gender, affected side, and MajorAxisLength. Finally, 4 machine learning receiver operating characteristics curves for random forest tree, support vector machine, generalized linear model, and extreme gradient boosting models were obtained for the clinical and imaging features of gender, affected side, drug, original_shape_MajorAxisLength, and original_shape_flatness. The areas under the receiver operating characteristics curves were 0.990, 0.993, 0.990, and 0.986, respectively. Finally, predictive column maps of affected side, gender, original_shape_flatness, and MajorAxisLength were constructed using the support vector machine method, and the area under the receiver operating characteristics curve of the model was 0.99, which suggests that the model had good predictive ability. Decision curve analysis  and calibration curves showed high applicability of column-line diagrams in clinical practice. Our validation cohort consisting of 60 patients had an area under the receiver operating characteristics curve of 0.857., Limitations: This study was performed in a single center. The nature of this study was retrospective rather than prospective and randomized, and it was not possible to entirely control for nuisance variables., Conclusion: Screening clinical information by machine learning, combined with a clinical imaging histology nomogram, has good potential for predicting the prognosis of a patient's TN treated with percutaneous balloon compression, and is suitable for clinical application in patients with TN after percutaneous balloon compression.

Purpose: Inferior alveolar nerve (IAN) and lingual nerve (LN) blocks are commonly performed using the intraoral landmark techniques. However, these methods have a risk of unanticipated nerve and arterial injury or a higher failure rate. We developed a novel extraoral approach for the IAN and LN blocks, the "inferior alveolar nerve block mandibular angle approach (IANB-MA)," using ultrasound guidance. The mechanism of action of this nerve block was examined anatomically, and its clinical feasibility was reported., Methods: We performed the IANB-MA on four cadavers using different dye volumes (2, 4, 6 and 8 mL). The ultrasound probe was placed on the lower edge of the mandibula of each cadaver, and the needle was advanced to the mandibular inner surface. Blue acrylic paint solution was injected, and its spread was evaluated by dissection., Results: Our study showed that the medial pterygoid muscle fascia was stained in all cadavers. The dye reached the LN consistently, and the IAN was stained with higher volumes (6 mL and 8 mL). The pterygomandibular space was filled with 6 mL and 8 mL of the dye. The IANB-MA successfully reduced pain in three patients with trigeminal neuralgia, tongue or jaw pain., Conclusions: The IANB-MA is a novel ultrasound-guided approach to the IAN and the LN. The clinical feasibility and effectiveness of this technique were confirmed in our patients. It may be a good alternative analgesic approach to other conventional approaches., Competing Interests: Declarations. Conflict of interest: All authors have no conflicts of interest., (© 2024. The Author(s) under exclusive licence to Japanese Society of Anesthesiologists.)

Abstract: Trigeminal neuralgia (TN) is characterized by excruciating facial pain usually caused by neurovascular compression of the trigeminal nerve roots. TN can be treated medically or invasively. Microvascular decompression is the procedure of choice and usually results in complete symptom relief. During surgical decompression, Teflon can be placed between the offending vessel and the nerve root entry zone. In some cases, chronic Teflon-related inflammation can cause recurrent TN, which might lead to additional surgical intervention. We present imaging and histopathological correlation of a patient presenting with intractable recurrent TN approximately 2 years after microvascular decompression with Teflon implant., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

The etiology of classical trigeminal neuralgia (CTN) is still unclear. A better understanding of the cerebral structural and functional changes in female patients with CTN may provide important novel insights into the pathophysiologic mechanisms of female CTN. A total 37 female CTN patients were included and referred to MRI scans, comprising with 19 left CTN and 18 right CTN patients. We analyzed the volume and shape of subcortical gray matter (GM), and the functional connectivity (FC) between the accumbens nucleus (NAc) and whole brain in right and left CTN patients respectively. We found left CTN patients had a reduced right NAc volume compared to controls, similarly, the right CTN had the decreased volume in the left NAc. Vertex-wise shapes of right NAc in left CTN patients showed significant regional shape deformation on the anterior, medial and ventroposterior aspects, in contrast, left NAc of right CTN patients showed significant regional shape deformation on the anterior and posterior aspect. Furthermore, patients with left CTN showed significantly lower FC between the right NAc and right orbitofrontal cortex than control subjects. The volume of NAc in all CTN was significantly related to the perception of present pain intensity. The CTN might be majorly caused by volume reduction in NAc. A greater understanding of the neurobiological basis of pain-related changes in NAc will provide the knowledge for the development of novel NAc based therapeutic targets for pain management or even prevention in CTN patients., Competing Interests: Declarations. Ethics approval and consent to participate: All procedures contributing to this work comply with the ethical standards of the relevant national and institutional committees on human experimentation and the Helsinki Declaration of 1975, as revised in 2008. The Clinical Trials and Biomedical Ethics Committee of Kunming Medical University approved our study protocol. All participants have written informed consent. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Objective: Microvascular decompression (MVD) in trigeminal neuralgia (TN) is currently managed using an operating microscope (OM). Recent experiences with endoscopy-assisted, fully endoscopic, and exoscopic surgery have been described, aiming to improve ergonomics and image quality. The aim of this study was to report the first series of patients operated on with the aid of a robotic binocular exoscope using a head-mounted display (RoboticScope)., Methods: From September 2023 to March 2024, 9 patients with TN were treated using the RoboticScope. A classic mini-retrosigmoid approach was performed and standard microsurgical techniques were applied. Surgical timing, ergonomics, visual performances, adverse events, and 1-month postoperative pain outcomes were evaluated., Results: All surgeries were completed without shifting to the OM. Surgeon comfort with the RoboticScope was better compared with the OM and visualization was good. No intraoperative adverse events were recorded. The duration of the procedure was significantly shorter with the RoboticScope compared to those using the OM (median 18 vs 34 minutes, p = 0.0001)., Conclusions: MVD can be safely and effectively performed using the RoboticScope. Surgeons benefit from better ergonomics, stereoscopic image quality, and shorter surgical duration.

Background: Patients with trigeminal neuralgia frequently undergo magnetic resonance imaging (MRI) prior to surgery. In patients without the signs and symptoms of face discomfort, MRI has shown the presence of neurovascular contact (NVC) in humans. Therefore, its capacity to accurately exclude NVC of the trigeminal nerve is not properly understood. A meta-analysis of the literature satisfied the criteria to further explore the value of MRI for the diagnosis of classical trigeminal neuralgia (CTN)., Study Design: The association between the symptomatic and asymptomatic trigeminal nerves, NVC, root entry zone (REZ), non-REZ, and anatomical variation was measured by a comprehensive review and meta-analysis of 13 observational studies using MRI for CTN neurovascular compression diagnosis., Objectives: This study aimed to evaluate the effectiveness of MRI in detecting the neurovascular compression that causes symptoms in individuals with classic trigeminal neuralgia., Setting: This study was conducted at the Department of Neurosurgery, Yantai Yuhuangding Hospital, Qingdao University., Methods: Digital searches of PubMed, Embase, and the Cochrane Library were performed to identify studies published until December 31, 2023. The following were evaluated: (1) MRI evidence of NVC in symptomatic and asymptomatic trigeminal nerves; (2) MRI indication of NVC at the REZ in symptomatic and asymptomatic trigeminal nerves; (3) MRI substantiation of non-REZ neurovascular contact in patients with CTN; and (4) asymptomatic and symptomatic anatomical changes at the NVC site of the trigeminal nerves. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using the fixed effects models., Results: We identified 13 observational studies (1 prospective and 12 retrospective studies) with data collected from 1770 nerves (728 symptomatic and 1042 asymptomatic) were meta-analyzed. First, MRI of 649/728 (88.2%) symptomatic versus 378/1042 (36.3%) asymptomatic trigeminal nerves revealed marked differences in NVC in the REZ (OR = 16.3; CI 95%=12.2-21.8; p < 0.00001). Second, pooled data showed that REZ NVC was detected in 206/262 (78.6%) symptomatic and in 129/340 (37.9%) asymptomatic nerves (OR = 5.0; CI 95% = 3.4-7.3; p < 0.00001); Third, no significant differences were detected between 44/267 (16.5%) symptomatic and 23/189 (12.1%) asymptomatic nerves on MRI examination of NVC in the NON-REZ (OR = 0.9; CI 95% 0.5-1.6) (p = 0.77); Finally, MRI revealed marked differences in 302/567 (53.2%) symptomatic and 73/919 (7.9%) asymptomatic anatomic changes (atrophy, dislocation, distorsion, flattening or indentation) at the NVC site of the trigeminal segments (OR = 11.9; CI 95% = 8.8-16.2; p < 0.00001)., Limitations: Despite the systematic evaluation of 13 observational studies, large-scale randomized controlled trials should be conducted, focusing on the specificity of MRI for the diagnosis of trigeminal neuralgia and evaluating the specificity of the imaging findings and the impact of the patient's postoperative treatment., Conclusions: A previous meta-analysis showed that patients with CTN were more likely to have NVC-specific anatomical changes. MRI of patients with CTN can detect anatomical changes in the REZ NVC with higher sensitivity., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: This study was conducted in accordance with the guidelines of the Declaration of Helsinki and all experimental protocol were approved by the Yantai Yuhuangding Hospital ethics committee. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background: Percutaneous rhizotomy of the Gasserian ganglion is a well-established intervention for patients suffering from refractory trigeminal pain, not amenable to pharmacological management or microvascular decompression. Traditionally conducted under fluoroscopic guidance using Hartel's technique, this study investigates a modified approach employing low-dose CT guidance to achieve maximal procedural precision and safety with the emphasis on minimizing radiation exposure., Methods: A retrospective analysis of patients undergoing percutaneous rhizotomy of the Gasserian ganglion at our institution was undertaken. Procedures were divided into fluoroscopy and CT-guided foramen ovale (FO) cannulation cohorts. Radiation doses were assessed, excluding cases with incomplete data. The study included 32 procedures in the fluoroscopy group and 30 in the CT group., Results: In the CT-guided group, the median effective dose was 0.21 mSv. The median number of CT scans per procedure was 4.5, and the median procedure time was 15 min. Successful FO cannulation was achieved in all 30 procedures (100%). In the fluoroscopy group, the median effective dose was 0.022 mSv, and the median procedure time was 15 min. Cannulation of FO was successful in 31 of 32 procedures (96.9%). The only complications in the CT-guided group were three minor cheek hematomas. Immediate pain relief in the CT-guided group was reported in 25 of 30 procedures (83.3%), 22 of 30 (73.3%) provided relief at one month, and 10 of 18 (55.6%) procedures resulting in pain relief at one month continued to provide relief after two years., Conclusion: Low-dose CT-guided percutaneous rhizotomy conducted in the radiology suite carries negligible radiation exposure for patients and eliminates it for personnel. This method is fast, simple, precise, and carries a very low risk of complications., Competing Interests: Declarations. Ethical approval: All procedures performed in studies involving human participants were in accordance with the ethical standards of the University Hospital Pilsen and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background and Purpose: Trigeminal neuralgia (TN) is a severe chronic pain condition, typically affecting patients over 50-year-old, caused by the compression of the nerve at the root entry zone (REZ) by blood vessels. While the diagnosis is clinical, advanced imaging like diffusion tensor imaging (DTI) is crucial to identify underlying causes and assessing nerve damage. DTI may help develop neuroimaging markers to improve understanding of TN and predict surgical outcomes. The goal of the present systematic review is to evaluate the effectiveness of DTI and tractography in order to better assess treatment planning and outcome prediction through the analysis of trigeminal nerve alterations., Methods: The authors conducted a systematic review and meta-analysis of the literature to compare radiological parameters identified in pre- and post-operative MRI with DTI sequences, including fractional anisotropy (FA), quantity of anisotropy (QA), radial diffusivity (RD), and to correlate these findings with post-operative clinical outcomes. A comprehensive search of the PubMed and Scopus databases was carried out for studies published between April 2010 and January 2024., Results: This review included 11 studies and 603 patients. Of the 363 patients with trigeminal neuralgia (TN), 193 underwent microvascular decompression (MVD), with 72.5% showing clinical improvement and 27.5% not improving, possibly due to chronic nerve damage. Four studies assessed radiological parameters before and after MVD, while two focused only on post-MVD data. The mean fractional anisotropy (FA) in affected nerves increased from 0.328 before MVD to 0.382 afterward. Five studies did not report postoperative outcomes, just comparing radiological parameters in TN patients versus healthy controls., Conclusions: Recent studies show that MRI-DTI parameters, including FA, RD, and QA, are useful for diagnosing trigeminal neuralgia and predicting treatment outcomes. Lower FA and higher RD values indicate better results after surgery. More research is mandatory to guide treatment decisions and enhance patients' care., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: The Hartel anterior approach is a commonly used puncture method in percutaneous balloon compression (PBC) surgery. However, anatomical variations along the puncture path, and visual errors on x-ray 2-dimensional imaging, may increase the difficulty of a successful first attempt. Our clinical practice has shown that employing the quadrant localization technique to plan puncture points and angles can enhance the puncture success rate., Objectives: We will demonstrate that the quadrant localization technique increases the success rate of the first puncture of the foramen ovale and the initial placement of the balloon catheter, thereby improving the efficiency of PBC surgery., Study Design: Retrospective study., Setting: A single center, tertiary general hospital., Methods: This study included a total of 371 patients with classic trigeminal neuralgia who underwent PBC surgery from January 2019 through May 2023. All patients received general anesthesia and underwent PBC surgery under radiographic guidance. In total, 170 patients underwent a puncture using the quadrant localization technique (Group Q), and 201 underwent a puncture using the conventional Hartel anterior approach (Group P)., Results: Group Q demonstrated higher success rates for the first puncture and insertion of the balloon catheter, along with a lower total radiographic radiation dose, shorter surgical duration, and shorter hospital stay (P < 0.05). However, there were no significant differences in PBC success rates or the incidence of puncture-related side effects and complications between the 2 groups (P > 0.05)., Limitations: This study lacked information on long-term complications and pain recurrence rates. Also, single-center results may be influenced by institution-specific practices and physician-related biases., Conclusion: In PBC surgery, the quadrant localization technique improves efficiency and reduces hospital stay compared with the conventional Hartel anterior approach, without increasing the risk of complications.

Purpose: Percutaneous lesioning-techniques for treating refractory Trigeminal Neuralgias not amenable to Micro-Vascular Decompression remain useful in neurosurgical practice. Success, avoidance of complications and reduction of side-effects depend on the accurate location of the lesion-maker especially for Radio-Frequency-Thermo-Rhizotomy (RF-Th-Rh). Added to X-ray-guidance, Intra-Operative Neurophysiology can be of significant help to achieve optimal accuracy of the surgery. Based on previous research, this article aims to describe the simplest way to use direct electrical stimulation of the trigeminal root to evoke clinically observable muscle responses allowing to precisely position the tip of the needle for accurate lesioning., Technique to Evoke Specific Localizing Muscle Responses: Masticatory twitches can be easily produced by stimulating the motor root, through orthodromic conduction to the masticatory muscles. Evoked Muscle Responses (EMRs) can be elicited in the facial nerve territory by stimulating the sensory rootlets, through Trigemino-Facial Reflexes' pathways (TFRs). Responses in the Orbicularis Oculi is the well-known and readily used "Blink reflex". On the contrary, TFRs in the lower territory of the facial nerve escaped clinical investigations not having been explored under direct stimulation of the trigeminal root. For both, stimulation at 5 c/s produces better observable twitches (because saccadic) than at 50 c/s which elicits tetanic contractions., Conclusion: The localizing-value of these facial EMRs (associated to evocation of paresthesias) and of the masticatory responses, justifies mapping the trigeminal root before lesioning. Their use could be extended to the other lesioning-techniques: not only Glycerol Neurolysis but also to Balloon Compression (to ascertain location of the trocar at the contact of the TGN inside the Meckel cave) and Open partial Rhizotomies (before deciding to cut the rootlets corresponding to the trigger-zone). This is of importance since lesioning-techniques are needed because not all trigeminal neuralgias are responsive to or even indications of Micro-Vascular Decompression., (© 2024. The Author(s).)

Objectives: This study aimed to develop a clinical-radiomics nomogram to predict the long-term outcomes of patients with classical trigeminal neuralgia (CTN) following microvascular decompression (MVD)., Materials and Methods: This retrospective study included 455 patients with CTN who underwent MVD from three independent institutions A total of 2030 radiomics features from the cistern segment of the trigeminal nerve were extracted computationally from the three-dimensional steady-state free precession and three-dimensional time-of-flight magnetic resonance angiography sequences. Using the least absolute shrinkage and selection operator regression, 16 features were chosen to develop radiomics signatures. A clinical-radiomics nomogram was subsequently developed in the development cohort of 279 patients via multivariate Cox regression. The predictive performance and clinical application of the nomogram were assessed in an external cohort consisting of 176 patients., Results: Sixteen highly outcome-related radiomics features extracted from multisequence images were used to construct the radiomics model, with concordance indices (C-index) of 0.804 and 0.796 in the development and test cohorts, respectively. Additionally, a clinical-radiomics nomogram was developed by incorporating both radiomics features and clinical characteristics (i.e., pain type and degree of neurovascular compression) and yielded higher C-indices of 0.865 and 0.834 in the development and test cohorts, respectively. K‒M survival analysis indicated that the nomogram successfully stratified patients with CTN into high-risk and low-risk groups for poor outcomes (hazard ratio: 37.18, p < 0.001)., Conclusion: Our study findings indicated that the clinical-radiomics nomogram exhibited promising performance in accurately predicting long-term pain outcomes following MVD., Clinical Relevance Statement: This model had the potential to aid clinicians in making well-informed decisions regarding the treatment of patients with CTN., Key Points: Trigeminal neuralgia recurs in about one-third of patients after undergoing MVD. The clinical-radiomics nomogram stratified patients into high- and low-risk groups for poor surgical outcomes. Using this nomogram could better inform patients of recurrence risk and allow for discussion of alternative treatments., (© 2024. The Author(s), under exclusive licence to European Society of Radiology.)

Background:  A neurovascular conflict (NVC) is considered the cause of trigeminal neuralgia (TN) in 75% of cases, and if so, a microvascular decompression (MVD) can lead to significant pain relief. A reliable preoperative detection of NVC is essential for clinical decision-making and surgical planning, making detailed neuroradiologic imaging an important component. We present our experiences and clinical outcomes with preoperative planning of the MVD procedure in a virtual reality (VR) environment, based on magnetic resonance imaging (MRI) including magnetic resonance angiography (MRA) and magnetic resonance venography (MRV) sequences., Methods:  We analyzed the data of 30 consecutive MVDs in patients treated for TN, in a retrospective single-surgeon (R.A. Kockro) study. Out of the 30 cases, 26 were included. Preoperatively, MRA/MRV and MRI series were fused and three dimensionally reconstructed in a VR environment. All critical structures such as the trigeminal nerve as well as the arteries and veins of the cerebellopontine angle, the brainstem, the neighboring cranial nerves, and the transverse and sigmoid sinus were segmented. The NVC was visualized and a simulation of a retrosigmoid approach, with varying trajectories, to the NVC was performed. The intraoperative findings were then compared with the data of the simulation. The clinical outcome was assessed by a detailed review of medical reports, and follow-up-interviews were conducted in all available patients (20/26)., Results:  The VR planning was well integrated into the clinical workflow, and imaging processing time was 30 to 40 minutes. There was a sole arterial conflict in 13 patients, a venous conflict in 4 patients, and a combined arteriovenous conflict in 9 patients. The preoperative simulations provided a precise visualization of the anatomical relationships of the offending vessels and the trigeminal nerves as well as the surrounding structures. For each case, the approach along the most suitable surgical corridor was simulated and the exact steps of the decompression were planned. The NVC and the anatomy of the cerebellopontine angle as seen intraoperatively matched with the preoperative simulations in all cases and the MVC could be performed as planned. At follow-up, 92.3% (24/26) of patients were pain free and all the patients who completed the questionnaire would undergo the surgery again (20/20). The surgical complication rate was zero., Conclusion:  Current imaging technology allows detailed preoperative visualization of the pathoanatomical spatial relationships in cases of TN. 3D interactive VR technology allows establishing a clear dissection and decompression strategy, resulting in safe vascular microsurgery and excellent clinical results., Competing Interests: None declared., (Thieme. All rights reserved.)

Background: Neurovascular compression (NVC) is a primary etiology of trigeminal neuralgia (TN) and hemifacial spasm (HFS). Despite Magnetic Resonance Tomographic Angiography (MRTA) being a useful tool for 3D multimodal fusion imaging (MFI) in microvascular decompression (MVD) surgery planning, it may not visualize smaller arterial vessels and veins effectively. We validate a novel computed tomography angiography and venography (CTA/V) - diffusion tensor tractography (DTT) -3D-MFI to enhance the MVD surgical guidance., Methods: In this prospective study, 80 patients with unilateral primary TN or HFS who underwent MVD surgery were included. Imaging was conducted using CTA/V-DTT-3D-MFI compared with CT-MRTA-3D-MFI in predicting the responsible vessel and assessing the severity of NVC. Surgical outcomes were subsequently analyzed. Neurosurgery residents were provided with questionnaires to evaluate and compare the two approaches., Results: CTA/V-DTT-3D-MFI significantly improved accuracy in identifying the responsible vessel (kappa = 0.954) and NVC (kappa = 0.969) compared to CT-MRTA-3D-MFI, aligning well with surgical findings. CTA/V-DTT-3D-MFI also exhibited higher sensitivity in identifying responsible vessels (98.0%) and NVC (98.7%) than CT-MRTA-3D-MFI. Additionally, CTA/V-DTT-3D-MFI showed fewer complications, shorter operation times, and lower recurrence after one year (all p < 0.05). Resident neurosurgeons emphasized that CTA/V-DTT-3D-MFI greatly assisted in formulating precise surgical strategies for more accurate identification and protection of responsible vessels and nerves (all p < 0.001)., Conclusion: CTA/V-DTT-3D-MFI enhances MVD surgery guidance, improving accuracy in identifying responsible vessels and NVC for better outcomes. This advanced imaging plays a crucial role in safer and more effective MVD surgery, as well as in training neurosurgeons., (© 2024. The Author(s).)

Microvascular decompression (MVD) has proven efficacy in trigeminal neuralgia (TN) and hemifacial spasm (HFS). This study utilized computational fluid dynamics (CFD) to investigate the impact of MVD on wall shear stress (WSS) of responsible arteries (RAs) at the neurovascular contact (NVC). A total of 21 cases (10 TN, 11 HFS) were analyzed, involving RAs at NVC validated through intraoperative photographs. Hemodynamic parameters (WSS, vessel diameter, flow rate, pressure drop) was calculated using CFD for the RAs based on 3D silent-magnetic resonance angiograms. The NVC was segmented into NVC-proximal, NVC-site, and NVC-distal portions using simulated 3D CFD images that correlated with surgical observations. WSS ratios of NVC-site to NVC-proximal (NVC-site/proximal) was calculated both before and after MVD. Prior to MVD, WSS in the RA at the NVC displayed a peaked curve with a maximum at NVC-site; however, post MVD, it presented a smooth curve without peaks. The WSS ratio exhibited a significant decrease after MVD. The impact of MVD on WSS of RAs at NVC was evaluated in both TN and HFS cases. Analyzing the hemodynamics of RAs through CFD and identifying WSS peaks at NVC portions before MVD provided a more detailed and localized understanding of the morphologically depicted NVC., (© 2024. The Author(s).)

Background: This study aims to utilize the deep learning method of VB-Net to locate and segment the trigeminal nerve, and employ radiomics methods to distinguish between CTN patients and healthy individuals., Methods: A total of 165 CTN patients and 175 healthy controls, matched for gender and age, were recruited. All subjects underwent magnetic resonance scans. VB-Net was used to locate and segment the bilateral trigeminal nerve of all subjects, followed by the application of radiomics methods for feature extraction, dimensionality reduction, feature selection, model construction, and model evaluation., Results: On the test set for trigeminal nerve segmentation, our segmentation parameters are as follows: the mean Dice Similarity Coefficient (mDCS) is 0.74, the Average Symmetric Surface Distance (ASSD) is 0.64 mm, and the Hausdorff Distance (HD) is 3.34 mm, which are within the acceptable range. Analysis of CTN patients and healthy controls identified 12 features with larger weights, and there was a statistically significant difference in Rad&#95;score between the two groups (p < 0.05). The Area Under the Curve (AUC) values for the three models (Gradient Boosting Decision Tree, Gaussian Process, and Random Forest) are 0.90, 0.87, and 0.86, respectively. After testing with DeLong and McNemar methods, these three models all exhibit good performance in distinguishing CTN from normal individuals., Conclusions: Radiomics can aid in the clinical diagnosis of CTN, and it is a more objective approach. It serves as a reliable neurobiological indicator for the clinical diagnosis of CTN and the assessment of changes in the trigeminal nerve in patients with CTN., (© 2024. The Author(s).)

Neurovascular compression syndrome (NVCS), characterized by cranial nerve compression due to adjacent blood vessels at the root entry zone, frequently presents as trigeminal neuralgia (TN), hemifacial spasm (HFS), or glossopharyngeal neuralgia (GN). Despite its prevalence in NVCS assessment, Magnetic Resonance Tomographic Angiography (MRTA)'s limited sensitivity to small vessels and veins poses challenges. This study aims to refine vessel localization and surgical planning for NVCS patients using a novel 3D multimodal fusion imaging (MFI) technique incorporating computed tomography angiography and venography (CTA/CTV). A retrospective analysis was conducted on 76 patients who underwent MVD surgery and were diagnosed with single-site primary TN, HFS, or GN. Imaging was obtained from MRTA and CTA/CTV sequences, followed by image processing and 3D-MFI using FastSurfer and 3DSlicer. The CTA/CTV-3D-MFI showed higher sensitivity than MRTA-3D-MFI in predicting responsible vessels (98.6% vs. 94.6%) and NVC severity (98.6% vs. 90.8%). Kappa coefficients revealed strong agreement with MRTA-3D-MFI (0.855 for vessels, 0.835 for NVC severity) and excellent agreement with CTA/CTV-3D-MFI (0.951 for vessels, 0.952 for NVC). Resident neurosurgeons significantly preferred CTA/CTV-3D-MFI due to its better correlation with surgical reality, clearer depiction of surgical anatomy, and optimized visualization of approaches (p < 0.001). Implementing CTA/CTV-3D-MFI significantly enhanced diagnostic accuracy and surgical planning for NVCS, outperforming MRTA-3D-MFI in identifying responsible vessels and assessing NVC severity. This innovative imaging modality can potentially improve outcomes by guiding safer and more targeted surgeries, particularly in cases where MRTA may not adequately visualize crucial neurovascular structures., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: Trigeminal neuralgia (TN) due to venous compression is far less common than that due to arterial compression, and its pathogenesis is less clear. We investigated the clinical and imaging features of TN caused by solely venous compression by measuring the morphologies of the posterior cranial fossa (PCF) and the trigeminal nerve., Methods: We retrospectively reviewed records of TN patients who underwent microvascular decompression at our institution and extracted cases with solely arterial or solely venous compression. Preoperative magnetic resonance imaging was used to find the length (Y), width (X), height (Z), and volume (V) of the PCF, the angle between the trigeminal nerve and pons, and the distance between Meckel's cave and the root entry zone of the trigeminal nerve., Results: Of 152 patients, 24 had TN caused solely by venous compression. The value of Y was significantly smaller in the venous group than the arterial group (P < 0.01). The trigeminal nerve and pons was significantly smaller in the venous group (P < 0.01). We hypothesized that TN patients with solely venous compression had a characteristic PCF morphology with a short anteroposterior diameter (Y), such that age-related changes in brain morphology could alter the course of the trigeminal nerve and cause compression by a vein., Conclusions: The morphological features of the PCF differed between patients with TN of venous and those with TN of arterial etiology. Age-related changes in brain morphology and changes of course of the trigeminal nerve may also add to the possibility of developing TN, especially of venous etiology., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: Introducing a preoperative image simulation technique to streamline the visualization of the foramen ovale in percutaneous microcompression., Methods: Twenty-five trigeminal neuralgia patients were included in the study. Preoperative cranial computed tomography scans were processed with 3D Slicer software to create simulated fluoroscopic skulls. The angulations required for precise visualization of the foramen ovale were established via simulated anteroposterior imaging. These simulations informed the C-arm's angulations for foramen ovale targeting during surgery., Results: The preoperative simulations accurately forecasted skull rotation angulations, aligning closely with intraoperative observations with negligible discrepancies (0-2 degrees). In 17 patients, the foramen ovale was distinctly visible, while in 8 patients, it was partially obscured yet discernible using the simulated angles. Nonvisible of the foramen ovale did not occur. Postoperative pain relief and complications were recorded., Conclusions: Based on our initial findings, the application of preoperative image simulation shows significant referential value in achieving accurate visualization of the foramen ovale in percutaneous microcompression for trigeminal neuralgia., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose: Trigeminal neuralgia (TN) is a chronic pain disorder defined by unilateral shock-like pain in at least one division of the trigeminal nerve. Although several studies have investigated structural brain plasticity in patients with TN, treatment-induced alterations remain largely uninvestigated., Methods and Materials: Combining T1-weighted magnetic resonance imaging with voxel-based morphometry and multiple-regression analyses, we assessed gray matter maps of patients with TN to investigate changes in gray matter volume (GMV) before and 6 months after stereotactic radiosurgery (SRS)., Results: Comparison of pre- and post-SRS GMV of 25 patients with TN (16 women; mean age 67 years) did not yield any significant clusters, suggesting that the effect of SRS intervention itself on gray matter structure may be negligible. Regarding SRS-induced pain relief, we found a significant GMV increase in the left superior frontal gyrus associated with greater degree of pain relief (P = .024) and a trend toward an increase in GMV in the left dorsolateral prefrontal cortex (P = .097)., Conclusions: In this pilot study, we observed significant increases in GMV in the left superior frontal gyrus with SRS-induced improvements in pain and a trend toward an increase in GMV in the dorsolateral prefrontal cortex. Future studies are indicated to validate these findings and determine whether SRS-induced decrease in distracting pain events and subsequent increases in GMV result in improved functionality, decreased dependence on "top-down" control, and improved cognitive/executive balance with amelioration of pain events., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Structural covariance networks and causal effects within can provide critical information on gray matter reorganization and disease-related hierarchical changes. Based on the T1WI data of 43 classical trigeminal neuralgia patients and 45 controls, we constructed morphological similarity networks of cortical thickness, sulcal depth, fractal dimension, and gyrification index. Moreover, causal structural covariance network analyses were conducted in regions with morphological abnormalities or altered nodal properties, respectively. We found that patients showed reduced sulcal depth, gyrification index, and fractal dimension, especially in the salience network and the default mode network. Additionally, the integration of the fractal dimension and sulcal depth networks was significantly reduced, accompanied by decreased nodal efficiency of the bilateral temporal poles, and right pericalcarine cortex within the sulcal depth network. Negative causal effects existed from the left insula to the right caudal anterior cingulate cortex in the gyrification index map, also from bilateral temporal poles to right pericalcarine cortex within the sulcal depth network. Collectively, patients exhibited impaired integrity of the covariance networks in addition to the abnormal gray matter morphology in the salience network and default mode network. Furthermore, the patients may experience progressive impairment in the salience network and from the limbic system to the sensory system in network topology, respectively., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background and Objective: Radiofrequency lesioning (RFL) is a safe and effective treatment for medically refractory trigeminal neuralgia. Despite gaining mainstream neurosurgical acceptance in the 1970s, the technique has remained relatively unchanged, with the majority of series using lateral fluoroscopy over neuronavigation for cannula guidance. To date, there are no studies describing neuronavigation-specific parameters to help neurosurgeons selectively target individual trigeminal rootlets. In this cadaveric study, we sought to provide a neuronavigation-specific morphometric roadmap for selective targeting of individual trigeminal rootlets., Methods: Embalmed cadaveric specimens were registered to cranial neuronavigation. Frontotemporal craniotomies were then performed to facilitate direct visualization of the Gasserian ganglion. A 19-gauge cannula was retrofit to a navigation probe, permitting real-time tracking. Using preplanned trajectories, the cannula was advanced through foramen ovale (FO) to the navigated posterior clival line (nPCL). A curved electrode was inserted to the nPCL and oriented inferolaterally for V3 and superomedially for V2. For V1, the cannula was advanced 5 mm distal to the nPCL and the curved electrode was reoriented inferomedially. A surgical microscope was used to determine successful contact. Morphometric data from the neuronavigation unit were recorded., Results: Twenty RFL procedures were performed (10R, 10L). Successful contact with V3, V2, and V1 was made in 95%, 90%, and 85% of attempts, respectively. Mean distances from the entry point to FO and from FO to the clival line were 7.61 cm and 1.26 cm, respectively., Conclusion: In this proof-of-concept study, we found that reliable access to V1-3 could be obtained with the neuronavigation-specific algorithm described above. Neuronavigation for RFL warrants further investigation as a potential tool to improve anatomic selectivity, operative efficiency, and ultimately patient outcomes., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Aim: Advanced neuroimaging strategies may provide new insights into the underlying mechanisms of trigeminal neuralgia (TN). The objective of this study is to measure central pain centers in patients with long-standing trigeminal neuralgia and compare them to those of normal individuals. The findings of this study could improve the understanding of central region changes related to pain and improve the diagnosis and management of chronic trigeminal pain., Material and Methods: We examined radiologic data from 20 patients with trigeminal neuralgia and 28 healthy controls who underwent 3D iso T1-weighted brain MRI at our university hospital between 2018 and 2023. Patients with a minimum pain duration of 5 years were included and compared with healthy controls. Additionally, patients were categorized into groups based on the presence of vascular compression. The pain-related subcortical structures, such as the cingulate cortex and insula, were analyzed volumetrically using volBrain software. The results were evaluated statistically., Results: Significant differences were observed in the measurement of the posterior insula (p = 0.014) when comparing patients with trigeminal neuralgia and healthy subjects. Additionally, group comparisons based on the presence of vascular compression revealed significant differences in the Middle Cingulate Cortex (0.036) and Posterior Cingulate Cortex (0.031) between groups, which may be related to the etiological factor., Conclusion: Understanding changes in central regions related to pain can aid in the diagnosis and management of chronic trigeminal pain., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: 3D-Slicer is an open-source medical image processing and visualization software. In the surgical treatment of trigeminal neuralgia, it is commonly used to predict the responsible vessels. However, there are few reports on the use of 3D-Slicer software to quantitatively measure the bilateral trigeminal nerve volume in patients with primary trigeminal neuralgia (PTN) based on the three-dimensional images. Therefore, this study aims to explore the role of three-dimensional fused images processed by 3D-Slicer in the evaluation of trigeminal nerve atrophy, providing an objective basis for the diagnosis of PTN., Methods: 57 PTN patients who underwent microvascular decompression (MVD) or percutaneous balloon compression (PBC) surgery in Hebei general hospital between January 2020 and April 2023 were included. Additionally, 30 patients with facial spasms(HFS) were included as a control group. All patients underwent 3D-TOF-MRA and 3D-FIESTA sequence examinations. Comparisons of bilateral trigeminal nerve volumes within and between groups were conducted by performing image fusion using 3D-slicer., Results: The volume of the affected trigeminal nerve in the MVD group (33.96 mm³±12.61 mm³) and PBC group (23.05 mm³±7.71 mm³) was smaller than that of the unaffected trigeminal nerve in the MVD group (39.61 mm³±12.83 mm³) and PBC group (26.14 mm³±6.42 mm³), as well as the average volume of the trigeminal nerve in the control group (40.27 mm³±10.25 mm³) (P<0.05). The differences in bilateral trigeminal ganglion volume (∆V) was significant between the MVD group (∆V=23.59 %±14.32 %) and the control group (∆V=14.64 %±10.00 %) (P<0.05). There was no statistical difference in the trigeminal nerve volume difference between the MVD group (∆V=23.59 %±14.32 %) and the PBC group (∆V=26.52 %±15.00 %) (P>0.05)., Conclusion: Trigeminal nerve atrophy is correlated with primary trigeminal neuralgia. 3D-slicer software can quantitatively measure trigeminal nerve volume and assist in the diagnosis of primary trigeminal neuralgia based on the difference in bilateral trigeminal nerve volumes. However, trigeminal nerve atrophy is not associated with postoperative pain recurrence in patients., Competing Interests: Declaration of Competing Interest All authors declare no conflicts of interest regarding the subject matter or materials discussed in this manuscript., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Chronic neuropathic pain can result from nervous system injury and can persist in the absence of external stimuli. Although ongoing pain characterizes the disorder, in many individuals, the intensity of this ongoing pain fluctuates dramatically. Previously, it was identified that functional magnetic resonance imaging signal covariations between the midbrain periaqueductal gray (PAG) matter, rostral ventromedial medulla (RVM), and spinal trigeminal nucleus are associated with moment-to-moment fluctuations in pain intensity in individuals with painful trigeminal neuropathy (PTN). Since this brainstem circuit is modulated by higher brain input, we sought to determine which cortical sites might be influencing this brainstem network during spontaneous fluctuations in pain intensity. Over 12 min, we recorded the ongoing pain intensity in 24 PTN participants and classified them as fluctuating ( n  = 13) or stable ( n  = 11). Using a PAG seed, we identified connections between the PAG and emotional-affective sites such as the hippocampal and posterior cingulate cortices, the sensory-discriminative posterior insula, and cognitive-affective sites such as the dorsolateral prefrontal (dlPFC) and subgenual anterior cingulate cortices that were altered dependent on spontaneous high and low pain intensity. Additionally, sliding-window functional connectivity analysis revealed that the dlPFC-PAG connection anticorrelated with perceived pain intensity over the entire 12 min period. These findings reveal cortical systems underlying moment-to-moment changes in perceived pain in PTN, which likely cause dysregulation in the brainstem circuits previously identified, and consequently alter the appraisal of pain across time., Competing Interests: The authors declare no competing financial interests., (Copyright © 2024 Meylakh et al.)

Objective: To study the value of three-dimensional CT (3D-CT) reconstruction by comparing the surgical effects of C-arm and 3D-CT in the treatment of trigeminal neuralgia (TN) by percutaneous balloon compression (PBC)., Methods: A total of 136 patients were included from May 2018 to February 2019. Among them, 65 patients underwent PBC treatment with 3D-CT and others with C-arm. During 3D-CT-guided operation, 3D-CT reconstruction software was used to analyze and measure the distances from the internal orifice of Foramen ovale (FO-I) and the external orifice of Foramen ovale (FO-E) to the top of the balloon (BT) and the petrous bone ridge (PR). The data, including the angle between the puncture needle direction and the zygomatic arch, petrous bone ridge, and slope, were used to assist the puncture and balloon plasty. Postoperative follow-up for more than five years was performed to evaluate the efficacy and pain recurrence., Results: The distance from FO-E to PR was (2.10 ± 0.16)cm, the average distance from FO-I to BT was (2.39 ± 0.07)cm, and the average angles between the puncture needle and zygomatic arch, slope, and petrous bone ridge were (56.19 ± 5.59)°, (69.12 ± 6.92)°, and (104.49 ± 6.46)°, respectively. One (1.5 %) patient in the 3D-CT group and three (4.2 %) patients in the C-arm group failed to receive PBC treatment because of failure of FO puncture (P = 0.032).In terms of postoperative pain improvement, 3D-CT group achieved better results than the C-arm group (P = 0.043). There were no significant differences in the rates of major complications and short-term recurrence (P = 0.926) between the two groups after surgery, but the five-year recurrence rate in the 3D-CT group was lower than that in the C-arm group (P = 0.032)., Conclusion: By guiding the angle and depth of puncture, the intraoperative application of 3D-CT reconstruction technology can improve the accuracy of foramen ovale puncture and alleviate postoperative pain, and also maintain long-term postoperative pain relief, which can be used as a potentially better guidance method to improve the surgical efficacy of PBC., 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 © 2024. Published by Elsevier Ltd.)

Background: The classic percutaneous balloon compression (PBC) technique is used to complete an operation under the guidance of C-arm radiography under general anesthesia, making communication with patients during the operation impossible. It is not accurate or objective to predict the classic technique's curative effect solely by determining whether the projection of the x-ray lateral image of the filled balloon is pear-shaped., Objectives: This study aimed to upgrade classic PBC to awake computed tomography (CT)-guided PBC technology under conscious local anesthesia and analgesia monitoring., Study Design: Prospective clinical study., Setting: Department of Anesthesiology and Pain Medical Center, Jiaxing, People's Republic of China., Methods: Puncture was designed and guided by CT scanning, and the curative effect was assessed by asking the patients about what they are feeling during the operation., Results: CT can design the puncture path and accurately guide puncture, observe the position and shape of the balloon through 3-dimensional reconstruction during the operation, and judge the curative effect according to the patient's chief concern., Limitations: Local anesthetic analgesia is not perfect, resulting in some patients experiencing pain during surgery., Conclusions: PBC can be completed under conscious local anesthesia and analgesia. Its curative effect and operative end standard can be determined according to the patient's chief concern. Under CT guidance, the puncture path can be designed to complete an accurate puncture and to intuitively understand the position and shape of the balloon.

Purpose: Secondary (TN) caused by an arachnoid cyst in the (CPA) region is a rare finding. Based on the reported literature, there are only 5 cases of secondary trigeminal neuralgia caused by an arachnoid cyst in the cerebellopontine angle region., Case Report: A 27-year-old female presented to our neurosurgery clinic with a 2-year history of brief episodes of paroxysm pain in the left cheek. The pain was described as an electric shock-like pain triggered by simple stimuli. The magnetic resonance imaging (MRI) showed a well-confined cystic lesion in the left CPA, which compresses the left pons and the cisternal segment of the left trigeminal nerve. The patient was managed operatively to fenestrate the cyst and decompress the trigeminal nerve. The histopathological result of the cyst wall was consistent with an arachnoid cyst. Six months after surgery, the patient is in good health condition and symptom-free without medication., Conclusion: Arachnoid cyst in the CPA region is one of the rare causes of secondary TN. Preoperative imaging with MRI is important to provide better results to differentiate the pathology. Surgical treatment to fenestrate the arachnoid cyst and decompress the trigeminal nerve have a good result and can improve the patient's quality of life.

Background: Radiofrequency thermorhizotomy (TRZ) is an established treatment for trigeminal neuralgia (TN). TRZ can result risky and painful in a consistent subset of patients, due to the need to perform multiple trajectories, before a successful foramen ovale cannulation. Moreover, intraoperative x-rays are required., Method: TRZ has been performed by using a neuronavigated stylet, before trajectory planning on a dedicated workstation., Conclusion: Navigated-TRZ (N-TRZ) meets the expectations of a safer and more tolerable procedure due to the use of a single trajectory, avoiding critical structures. Moreover, N-TRZ is x-ray free. Efficacy outcomes are similar to those reported in literature., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Microvascular decompression (MVD) is a well-established and definitive treatment option for trigeminal neuralgia (TN). 1 However, complex vascular geometry and numerous offending vessels make it difficult to perform nerve decompression in certain cases. 2 The trigeminocerebellar artery (TCA) is a unique branch of the basilar artery. The vessel is named the TCA because it supplies both the trigeminal nerve root and the cerebellar hemisphere. 3 This anatomical variant may increase the risk of neurovascular compression in the trigeminal nerve. We present the case of a 74-year-old man with left TN in whom a TCA was one of the responsible compression vessels. Preoperative images revealed the ipsilateral anterior inferior cerebellar artery, well-developed TCA, and superior cerebellar artery, wherein these branches were all suspected to be involved in trigeminal nerve compression. In MVD, 3 arteries were suspected to compress the trigeminal nerve in 5 sites, and all of them needed to be meticulously dissected from the nerve root and decompressed. Moreover, 2 of them branched many short perforators to the brainstem. Three decompression procedures (transposition to the dura, transposition to the brain, and interposition) were performed to decompress the trigeminal nerve. Postoperatively, TN was completely resolved immediately. MVD for TN could be difficult to perform in cases with TCA, as in the present case, and rigorous procedures were required intraoperatively., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Trigeminal neuralgia (TN) is a highly debilitating facial pain condition. Magnetic resonance imaging (MRI) is the main method for generating insights into the central mechanisms of TN pain in humans. Studies have found both structural and functional abnormalities in various brain structures in TN patients as compared with healthy controls. Whereas studies have also examined aberrations in brain networks in TN, no studies have to date investigated causal interactions in these brain networks and related these causal interactions to the levels of TN pain. We recorded fMRI data from 39 TN patients who either rested comfortably in the scanner during the resting state session or tracked their pain levels during the pain tracking session. Applying Granger causality to analyze the data and requiring consistent findings across the two scanning sessions, we found 5 causal interactions, including: (1) Thalamus → dACC, (2) Caudate → Inferior temporal gyrus, (3) Precentral gyrus → Inferior temporal gyrus, (4) Supramarginal gyrus → Inferior temporal gyrus, and (5) Bankssts → Inferior temporal gyrus, that were consistently associated with the levels of pain experienced by the patients. Utilizing these 5 causal interactions as predictor variables and the pain score as the predicted variable in a linear multiple regression model, we found that in both pain tracking and resting state sessions, the model was able to explain ∼36 % of the variance in pain levels, and importantly, the model trained on the 5 causal interaction values from one session was able to predict pain levels using the 5 causal interaction values from the other session, thereby cross-validating the models. These results, obtained by applying novel analytical methods to neuroimaging data, provide important insights into the pathophysiology of TN and could inform future studies aimed at developing innovative therapies for treating TN., Competing Interests: Declaration of Competing Interest The authors declare no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

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., (© 2024. The Author(s).)

Achieving a pear-shaped balloon holds pivotal significance in the context of successful percutaneous microcompression procedures for trigeminal neuralgia. However, inflated balloons may assume various configurations, whether it is inserted into Meckel's cave or not. The absence of an objective evaluation metric has become apparent. To investigate the relationship between the morphology of Meckel's Cave and the balloon used in percutaneous microcompression for trigeminal neuralgia and establish objective criteria for assessing balloon shape in percutaneous microcompression procedures. This retrospective study included 58 consecutive patients with primary trigeminal neuralgia. Data included demographic, clinical outcomes, and morphological features of Meckel's cave and the balloon obtained from MRI and Dyna-CT imaging. MRI of Meckel's cave and Dyna-CT of intraoperative balloon were modeled, and the morphological characteristics and correlation were analyzed. The reconstructed balloon presented a fuller morphology expanding outward and upward on the basis of Meckel's cave. The projected area of balloon was strongly positively correlated with the projected area of Meckel's cave. The Pearson correlation coefficients were 0.812 (P<0.001) for axial view, 0.898 (P<0.001) for sagittal view and 0.813 (P<0.001) for coronal view. Similarity analysis showed that the sagittal projection image of Meckel's cave and that of the balloon had good similarity. This study reveals that the balloon in percutaneous microcompression essentially represents an expanded morphology of Meckel's cave, extending outward and upward. There is a strong positive correlation between the volume and projected area of the balloon and that of Meckel's cave. Notably, the sagittal projection image of Meckel's cave serves as a reliable predictor of the intraoperative balloon shape. This method has a certain generalizability and can help providing objective criteria for judging balloon shape during percutaneous microcompression procedures., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Mapping the localization of the functional brain regions in trigeminal neuralgia (TN) patients is still lacking. The study aimed to explore the functional brain alterations and influencing factors in TN patients using functional brain imaging techniques. All participants underwent functional brain imaging to collect resting-state brain activity. The significant differences in regional homogeneity (ReHo) and amplitude of low frequency (ALFF) between the TN and control groups were calculated. After familywise error (FWE) correction, the differential brain regions in ReHo values between the two groups were mainly located in bilateral middle frontal gyrus, bilateral inferior cerebellum, right superior orbital frontal gyrus, right postcentral gyrus, left inferior temporal gyrus, left middle temporal gyrus, and left gyrus rectus. The differential brain regions in ALFF values between the two groups were mainly located in the left triangular inferior frontal gyrus, left supplementary motor area, right supramarginal gyrus, and right middle frontal gyrus. With the functional impairment of the central pain area, the active areas controlling memory and emotion also change during the progression of TN. There may be different central mechanisms in TN patients of different sexes, affected sides, and degrees of nerve damage. The exact central mechanisms remain to be elucidated., (© 2024. The Author(s).)

Background: Target selection during Gamma Knife radiosurgery (GKRS) in cases of tumor-related trigeminal neuralgia is always debatable. We analyzed the correlation of regression of tumor size and degree of release of the nerve with long-term pain control., Methods: Between March 2012 and March 2023, 50 cases of tumor-related trigeminal neuralgia were treated with GKRS (tumor was targeted). Radiological findings after GKRS were categorized into 3 types: 1) tumor volume remained same or decreased, additional segment of nerve not seen; 2) tumor volume decreased, additional segment of trigeminal nerve seen, but tumor still adherent to the nerve; 3) tumor volume decreased, adjacent nerve seen completely separated from tumor. Pain score before and after GKRS (Barrow Neurological Institute I-III: good; Barrow Neurological Institute IV and V: poor) was correlated with these subgroups., Results: At median follow-up of 46.5 months, 18 cases showed type 1 radiological response, 23 showed type 2 response, and 9 showed type 3 response. Good pain control was achieved in 10 (55.5%) patients with type 1, 15 (65.21%) with type 2, and 7 (77.8%) with type 3 responses. The outcome differences among these 3 groups were not statistically significant (P = 0.519). Five patients with type 3 radiological response were off medication, which was statistically better than type 1 and type 2 radiological responses, with 3 patients (P = 0.012) and 2 patients (P = 0.002), respectively, still receiving medication., Conclusions: Tumor volume reduction after GKRS may be associated with good pain control in tumor-related trigeminal neuralgia. Further, this allows visualization of additional segment of nerve that can be targeted in a second session for treating recurrent or failed cases., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Classical trigeminal neuralgia (CTN) refers to episodic pain that is strictly confined to the trigeminal distribution area, and the thalamus is an important component of the trigeminal sensory pathway. Probabilistic tracking imaging algorithm was used to identify specific connections between the thalamus and the cortex, in order to identify structural changes in the thalamus of patients with CTN and perform thalamic segmentation. A total of 32 patients with CTN and 32 healthy controls underwent DTI-MRI scanning (3.0 T). Differences in fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD) and mean diffusivity (MD) between the groups were studied. Correlation analysis was performed with clinical course and pain level. Compared to the healthy controls, patients in the CTN group had significantly reduced FA, increased AD, RD and MD in somatosensory subregion of the bilateral thalamus, increased RD in frontal subregion, increased RD and MD in motor subregion. Correlation analysis showed that patient history was positively correlated with pain grading, and that medical history was positively correlated with significantly reduced FA in somatosensory subregion, negatively correlated with increased RD and MD in motor subregion. We used DTI-based probabilistic fiber tracking to discover altered structural connectivity between the thalamus and cerebral cortex in patients with CTN and to obtain a thalamic segmentation atlas, which will help to further understand the pathophysiology of CTN and serve as a future reference for thalamic deep brain stimulation electrode implantation for the treatment of intractable pain., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Trigeminal neuralgia (TN), a severe facial pain condition, is often treated with microvascular decompression (MVD). While MVD is effective for arterial neurovascular compression, its efficacy in cases of venous compression and the intraoperative management of such cases remain areas of debate. This review aimed to analyze the intraoperative management strategies for offending veins during MVD and evaluate the outcomes of these procedures in cases of TN with purely venous compression. An extensive review of studies reporting on the intraoperative handling of veins and the surgical outcomes of MVD in purely venous compression cases was conducted. Fifteen full-text studies were included, encompassing a total of 600 patients. Notably, 82.33% of these patients achieved a Barrow Neurological Institute (BNI) I pain score, with follow-up periods ranging from 3 months to 12 years. MVD is a viable and effective treatment option for TN in cases of venous compression, with a significant proportion of patients experiencing substantial pain relief., Competing Interests: The authors declare no conflict of interest., (© 2024 by the authors.)

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.

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., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Magnetic resonance-diffusion tensor imaging (MR-DTI) has been used in the microvascular decompression and gamma knife radiosurgery in trigeminal neuralgia (TN) patients; however, use of percutaneous stereotactic radiofrequency rhizotomy (PSR) to target an abnormal trigeminal ganglion (ab-TG) is unreported. Fractional anisotropy (FA), mean and radial diffusivity (MD and RD, respectively), and axial diffusivity (AD) of the trigeminal nerve (CNV) were measured in 20 TN patients and 40 healthy control participants immediately post PSR, at 6-months, and at 1 year. Longitudinal alteration of the diffusivity metrics and any correlation with treatment effects, or prognoses, were analyzed. In the TN group, either low FA (value < 0.30) or a decreased range compared to the adjacent FA (dFA) > 17% defined an ab-TG. Two-to-three days post PSR, all 15 patients reported decreased pain scores with increased FA at the ab-TG (P < 0.001), but decreased MD and RD (P < 0.01 each). Treatment remained effective in 10 of 14 patients (71.4%) and 8 of 12 patients (66.7%) at the 6-month and 1-year follow-ups, respectively. In patients with ab-TGs, there was a significant difference in treatment outcomes between patients with low FA values (9 of 10; 90%) and patients with dFA (2 of 5; 40%) (P < 0.05). MR-DTI with diffusivity metrics correlated microstructural CNV abnormalities with PSR outcomes. Of all the diffusivity metrics, FA could be considered a novel objective quantitative indicator of treatment effects and a potential indicator of PSR effectiveness in TN patients., (© 2024. The Author(s).)

Objective: Percutaneous microballoon compression (PMC) is a simple and effective surgical procedure for the treatment of trigeminal neuralgia. The difficulty with this surgery is related to accurate and quick foramen ovale puncture. In this study, we compared the application of personalized 3D-printed guides and the traditional puncture method in trigeminal PMC surgery., Method: Data from 40 patients with primary trigeminal neuralgia treated with PMC between June 2017 and August 2019 were analyzed retrospectively. Personalized 3D-printed jigs were used to assist foramen ovale puncture in 20 patients, and Hartel positioning was used for puncture in 20 patients. Three-dimensional reconstruction was performed preoperatively using 3DSlicer software to understand the size of the foramen ovale and positioning of related anatomical structures. Based on the reconstruction, personalized surgical paths were created for the jig plate-assisted treatment group, and the printed jig plate was applied to the surgery through 3D printing to explore the surgical effect., Results: Foramen ovale puncture was successful in all patients. Better results were achieved with guides than with the traditional method in terms of the foramen ovale puncture time ( p  < 0.01), total operation time ( p  < 0.01), and number of computed tomography scans ( p  < 0.01). The efficacy of surgery and postoperative complications did not differ between groups ( p  = 1)., Conclusions: The use of personalized 3D-printed guides enables accurate puncture positioning in PMC, and improves the success rate of surgery, shortens the operation time, and reduces surgical risk, which has broad prospects in clinical application.

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., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc on behalf of Congress of Neurological Surgeons.)