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The removal of vestibular schwannomas carries a risk of facial palsy. This study aims to evaluate the usefulness and technical aspects of intraoperative monitoring (IOM) for the facial nerve. A total of 96 patients who underwent surgery for vestibular schwannoma were retrospectively investigated. The cohort was divided into two groups: those with intraoperative facial nerve monitoring (IOM group) and those without IOM (non-IOM group). Preoperative and postoperative facial nerve functions were assessed using the House-Brackmann (HB) scale immediately after surgery, at discharge, and at the 1-year follow-up. HB grade I and II were classified as satisfactory outcomes, HB grade III and IV as intermediate, and HB grade V and VI as poor. Facial nerve functions were compared between the groups. Additionally, the ratio of satisfactory results was investigated in the IOM group, focusing on whether the root exit zone (REZ) was identified at an early or late stage of surgery. Among the 65 (67%) patients in the IOM group and 31 (32%) patients in the non-IOM group, there were no differences in demographic and tumor characteristics. The extent of resection varied from subtotal to gross total removal, with no statistical differences between the groups. Although facial nerve function was more favorably preserved in the non-IOM group immediately after surgery, this trend reversed at discharge and the 1-year follow-up, showing significant statistical differences. In the IOM group, more patients achieved satisfactory outcomes when the REZ was identified early compared to late during tumor resection. Intraoperative facial nerve monitoring provides more satisfactory outcomes in preserving nerve function in vestibular schwannoma surgery. Early recognition of the REZ may contribute to improved surgical outcomes., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: In microvascular decompression (MVD) procedures for hemifacial spasm (HFS), surgeons often encounter a rhomboid lip which may obscure the root exit zone (REZ) of the facial nerve. This study aims to explore the anatomical variations of rhomboid lips and their surgical implications to improve safety and effectiveness in MVD surgeries., Methods: A retrospective analysis was conducted on 111 patients treated for HFS between April 2021 and March 2023. The presence of a rhomboid lip was assessed through operative video records, and its characteristics, dissection methods, and impact on nerve decompression outcomes were further examined. Preoperative magnetic resonance imaging (MRI) scans were reviewed for detectability of the rhomboid lip., Results: Rhomboid lips were identified in 33% of the patients undergoing MVD, with a higher prevalence in females and predominantly on the left side. Two distinct types of rhomboid lips were observed: membranous and cystic variations. The membranous type was noted for its smaller size and position ventral to the choroid plexus. In contrast, the cystic variation was distinguished by its larger size and a thin membrane that envelops the choroid plexus. Preoperative MRI successfully identified rhomboid lips in only 21% of the patients who were later confirmed to have them in the surgical procedures. Surgical approaches primarily involved incisions on the dorsal wall and along the glossopharyngeal nerve root, with only limited need for extensive dissection from lower cranial nerves. Immediate spasm relief was observed in 97% of the patients. One case exhibited a lower cranial nerve deficit accompanied by brainstem infarction, which was caused by the dissection from the lower cranial nerves., Conclusions: Recognizing the two variations of the rhomboid lip and understanding their anatomical structures are essential for reducing lower cranial nerve injuries and ensuring effective nerve decompression., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: Microvascular decompression (MVD) is effective for refractory trigeminal neuralgia (TN), but its accessibility is often limited in lower-to-middle-income countries (LMICs). This study aims to assess the impact of implementing a single-surgeon policy on MVD for TN in LMICs., Methods: A prospective cohort study was conducted from 2014 to 2020, comparing outcomes between multi-surgeon and single-surgeon policies. Residents were included in MVD procedures starting in 2019. The Barrow Neurological Institute (BNI) pain scale (P), numbness scale (N), and result conclusion scale (P + N) were used to evaluate outcomes (1 week, 1 month, 1 year, and yearly thereafter). Propensity score matching was performed before comparing the groups. Pain-free survival was assessed using Kaplan-Meier and Cox-regression analysis., Results: We comprehensively analyzed data from 72 patients with a minimum one-year follow-up. The implementation of the single-surgeon policy had several notable impacts. Firstly, it led to an increased referral rate (p < 0.05) and a reduced duration to surgery (p < 0.05). During MVD, there was a significant increase in the identification of complex compression (p < 0.05) and a reduced frequency of internal neurolysis (p < 0.05). After surgery, the single-surgeon group exhibited a superior pain-control profile (RR 1.9, p < 0.001; ARR 26-36%), higher pain-free survival rate (p < 0.001), lower likelihood of pain recurrence (HR 0.2, p < 0.0001), and fewer additional surgical interventions compared to the multi-surgeon group. Moreover, the involvement of residents did not significantly impact surgical outcomes., Conclusions: Implementing a single-surgeon policy for MVD in LMICs has the potential to improve surgical outcomes, provide social benefits, and offer educational opportunities., 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 © 2023 Elsevier Ltd. All rights reserved.)

Trigeminal neuralgia (TN) is a neuropathic pain that can be treated with microvascular decompression (MVD) or percutaneous radiofrequency rhizotomy (PRR) when medications fail. However, the cost-effectiveness of these interventions is uncertain, and it is unclear whether TN should be considered as a single entity for cost-effectiveness analysis. To address these issues, a prospective cohort study was conducted between 2017 and 2020, documenting Burchiel et al.'s clinical classification, pain-free survival, complications, and costs. Two models of quality-adjusted life years (QALYs) were calculated: pain-specific (PQALY) and pain-complication-specific (PCQALY), based on pain-free survival and complications data, followed by cost-effectiveness analysis. The study included 112 patients, of whom 70 underwent MVD and 42 underwent PRR. Our findings revealed that MVD was less cost-effective in the PCQALY model than PRR, but more cost-effective in the PQALY model and had an incremental cost-effectiveness ratio (ICER) that met the World Health Organization cost-effectiveness threshold in both models. Further clinical classification analysis showed that MVD was only cost-effective in type 1 TN patients, with an ICER of 0.9 and 1.3 times the GDP/capita, based on PQALY and PCQALY, respectively, meeting the cost-effectiveness criteria. Conversely, MVD was economically dominated by PRR for type 2 TN patients based on PQALY. These findings indicate that PRR may be more cost-effective for type 2 TN patients, while MVD remains the cost-effective option for type 1 TN patients. Our study highlights the importance of clinical classification and complication in determining the cost-effectiveness of MVD and PRR for refractory TN., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: A thorough observation of the root exit zone (REZ) and secure transposition of the offending arteries is crucial for a successful microvascular decompression (MVD) for hemifacial spasm (HFS). Decompression procedures are not always feasible in a narrow operative field through a retrosigmoid approach. In such instances, extending the craniectomy laterally is useful in accomplishing the procedure safely. This study aims to introduce the benefits of a skull base approach in MVD for HFS., Methods: The skull base approach was performed in twenty-eight patients among 335 consecutive MVDs for HFS. The site of the neurovascular compression (NVC), the size of the flocculus, and the location of the sigmoid sinus are measured factors in the imaging studies. The indication for a skull base approach is evaluated and verified retrospectively in comparison with the conventional retrosigmoid approach. Operative outcomes and long-term results were analyzed retrospectively., Results: The extended retrosigmoid approach was used for 27 patients and the retrolabyrinthine presigmoid approach was used in one patient. The measurement value including the site of NVC, the size of the flocculus, and the location of the sigmoid sinus represents well the indication of the skull base approach, which is significantly different from the conventional retrosigmoid approach. The skull base approach is useful for patients with medially located NVC, a large flocculus, or repeat MVD cases. The long-term result demonstrated favorable outcomes in patients with the skull base approach applied., Conclusions: Preoperative evaluation for lateral expansion of the craniectomy contributes to a safe and secure MVD., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Trigeminal Neuralgia is commonly triggered by stimuli in the area of the trigeminal nerve innervation. We report an exceptionally rare case of a 61-year-old woman who complained of recurrent trigeminal neuralgia, which sole trigger was seeing a bright light. Teflon felt that was placed on the nerve root in the initial surgery was suspected of causing this rare type of trigeminal neuralgia. A reflex circuit linking luminance to trigeminal nerve activity may be implicated in activating a trigeminal nociceptive pathway by a bright light trigger., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2022 Prasetya, Adidharma, Inoue, Sulistyanto, Fadhil, Oswari, Keswani, Kusdiansah, Aji and Arham.)