Anatomical considerations and surgical manipulation of the rhomboid lip in microvascular decompression for hemifacial spasm.

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.

Potential reasons for failure and recurrence in microvascular decompression for hemifacial spasm.

BACKGROUND: To examine the factors contributing to persistent and recurrent hemifacial spasms (HFS) following a microvascular decompression (MVD) procedure and to suggest technical improvements to prevent such failures. METHODS: A retrospective review was conducted on fifty-two cases of repeat surgery. The extent of the previous craniotomy and the location of neurovascular compression (NVC) were investigated. The operative findings were categorized into two groups: "Missing Compression" and "Teflon Contact". The analysis included long-term outcomes and operative complications after repeat MVD procedures. RESULTS: Missing compression was identified in 29 patients (56%), while Teflon contact was observed in 23 patients (44%). Patients with missing compression were more likely to experience improper craniotomy (66%) compared to those with Teflon contact (48%). Medially located NVC was a frequent finding in both groups, mainly due to compression by the anterior inferior cerebellar artery. In the missing compression group, during the repeat MVD, Teflon sling retraction was utilized in 79% of cases, while in the Teflon contact group, the most common procedure involved removing the Teflon in contact (65%). After the repeat MVD procedure, immediate spasm relief was achieved in 42 patients (81%), with six (12%) experiencing delayed relief. After a median follow-up of 54 months, 96% of patients were free from spasms. Delayed facial palsy, facial weakness, and hearing impairment were more frequently observed in the Teflon contact group. CONCLUSIONS: A proper craniotomy that provides adequate exposure around the REZ is crucial to prevent missing the culprit vessel during the initial MVD procedure. Teflon contact on the REZ should be avoided, as it poses a potential risk of procedure failure and recurrence.

Single-surgeon approach in microvascular decompression for trigeminal neuralgia: Lessons from an Indonesian Tertiary-Level Neurological Center.

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.

Analyzing the cost-effectiveness of microvascular decompression and percutaneous radiofrequency rhizotomy for trigeminal neuralgia: the role of clinical classification.

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.

Case report: Teflon granuloma following microvascular decompression manifesting as light-triggered trigeminal neuralgia.

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.

Characteristics of Patients With Trigeminal Neuralgia Referred to the Indonesian National Brain Center Neurosurgery Clinic.

Trigeminal neuralgia (TN) is a debilitating neuropathic pain involving the fifth cranial nerve. There has been no study investigating the clinical and socioeconomical characteristics of patients with TN in Indonesia. A total of 100 patients were included in this study. Symptoms indicating a later stage of the illness, namely, involvement of all the trigeminal nerve branches, numbness, and concomitant persistent pain, were the common presentations found in our cohort. Only one TN diagnosis was made by a general practitioner (GP). None were immediately referred to a neurosurgeon following their diagnosis. Access to our clinic took as long as 4.7 ± 5.1 years (mean ± SD) from the onset. Older age was a significant predictor of an increased likelihood of not knowing their illness upon the referral (21.9%, p = 0.008). Upon their first presentation, 25.5% of patients had experienced drug-related side effects due to prolonged medication. Only 50% of patients were compensated by the universal health coverage (UHC) system. Seven patients spent ≥ 50 million rupiahs and eight patients had already lost their jobs. In conclusion, early contact with a neurosurgeon contributes to better management of TN, both for the patients and healthcare system in Indonesia. A refined understanding of TN nature is still needed in this country.