Tag: Trigeminal neuralgia

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Gamma Knife radiosurgery for relapsing trigeminal neuralgia following microvascular decompression

J Neurosurg 142:1247–1255, 2025

Salvage Gamma Knife radiosurgery (GKRS) offers effective, noninvasive treatment for relapsing trigeminal neuralgia after microvascular decompression, with a favorable complications profile. Patients with facial numbness and better initial pain responses may experience more durable pain relief following salvage GKRS.

• Gamma Knife radiosurgery (GKRS) is explored as a treatment for relapsing trigeminal neuralgia (TN) following microvascular decompression (MVD).

• The study aimed to assess the response rate, complications, and predictors of pain relapse for salvage GKRS after MVD.

• 83.1% of patients experienced initial pain relief after salvage GKRS, with a median time to relapse of 1.75 years.

• Facial numbness post-GKRS decreased pain relapse risk, while a worse initial pain response increased it.

• Radiofrequency ablation (RFA) prior to MVD reduced the likelihood of an initial response to GKRS.

• Salvage GKRS is presented as an effective, noninvasive option for recurring TN after MVD, with a favorable complications profile compared to salvage MVD.

• The study acknowledges limitations, including potential selection bias and small sample size, and suggests further research with larger cohorts

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Morphological analysis of the trigeminal nerve in trigeminal neuralgia using the nerve’s centerline and multiple cross-sections of a 3D model

J Neurosurg 142:884–891, 2025

• Study Objective: Quantify morphological changes in trigeminal nerve causing trigeminal neuralgia (TN).

• Methods: Retrospective analysis of patients with TN undergoing microvascular decompression (MVD).

• Parameters Analyzed: Centerline length, curvature, torsion, cross-sectional area, flattening ratio, long-axis angle.

• Results: Affected side showed longer centerline, greater curvature, smaller area pre-surgery.

• Postoperative Changes: Affected side showed shorter centerline, larger cross-sectional area post-surgery.

• Concordance Rate: 91.4% between intraoperative findings and 3D model flexion locations.

• Accuracy of Segmentation: Manual segmentation showed 80%-90% concordance with surgical findings.

• Limitations: Retrospective, single institution, manual segmentation, not fully matching surgical findings.

• Further Analyses: Needed for patients without neurovascular compression (NVC) and with venous compression.

• Study Implications: Method helps analyze TN pathophysiology, aid diagnosis, predict treatment efficacy.

• Statistical Analysis: Mann-Whitney U-test, significance set at p < 0.05

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Tobacco Use and Trigeminal Neuralgia: Clinical Features and Outcome After Microvascular Decompression

Neurosurgery 96:667–672, 2025

• Tobacco use affects trigeminal neuralgia (TN) outcomes: Smokers with TN tend to develop symptoms at a younger age and have worse long-term outcomes after microvascular decompression (MVD) surgery compared to nonsmokers.

• Smokers show more widespread facial pain: TN in smokers is associated with a more widespread distribution of facial pain, suggesting a more severe form of the disease.

• Immediate postoperative outcomes similar: There is no significant difference in immediate postoperative outcomes between smokers and nonsmokers, although smokers are less likely to be pain-free in the long term.

• Potential benefits of smoking cessation: Patients with a remote history of smoking have outcomes similar to those who never smoked, indicating potential benefits of quitting smoking before surgery.

• Study limitations: The study is a single-center retrospective analysis and may not be generalizable to all TN patients or those undergoing different treatments.

• Implications for treatment: Findings suggest the need for presurgical counseling and support for smoking cessation to improve outcomes for TN patients undergoing MVD.

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Microvascular Decompression Using the Gelatin Sponge Insertion Technique for Trigeminal Neuralgia

Operative Neurosurgery 28:52–58, 2025

Microvascular decompression (MVD) is the primary surgical intervention for trigeminal neuralgia (TN), with Teflon being the most conventional decompressing material. However, Teflon has been associated with adhesion and granulomas after MVD, which closely correlated with the recurrence of TN. Therefore, we developed a new technique to prevent direct contact between Teflon and nerve. The purpose of this study is to compare the efficacy of MVD using the gelatin sponge (GS) insertion technique with that of Teflon inserted alone in treating primary TN.

METHODS: We retrospectively analyzed the medical records and the follow-up data of 734 patients with unilateral primary TN who underwent MVD at our center from January 2014 to December 2019. After exclusions, we identified 313 cases of GS-inserted MVD and 347 cases of traditional MVD. The follow-up exceeded 3 years.

RESULTS: The operating time of the GS-inserted group was longer than that of the Teflon group (109.38 ± 14.77 vs 103.53 ± 16.02 minutes, P < .001). There was no difference between 2 groups in immediate surgical outcomes and postoperative complications. The yearly recurrence rate for GS-inserted MVD was lower at first (1.0%), second (1.2%), and third (1.2%) years after surgery, compared with its counterpart of Teflon group (3.7%, 2.9%, and 1.7% respectively). The first-year recurrence rate (P = .031) and total recurrence rate in 3 years (P = .013) was significantly lower in the GS-inserted group than Teflon group. Kaplan–Meier survival analysis demonstrated better outcomes in GS-inserted Microdescompresión vascular groups (P = .020).

CONCLUSION: The application of the GS insertion technique in MVD reduced first-year postoperative recurrence of TN, with similar complications rates compared with traditional MVD.

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Anterior selective targeting for radiosurgical treatment of trigeminal neuralgia: a cohort study

Acta Neurochirurgica (2024) 166:482

Before commonly used targets such as the Retrogasserian Zone (RGZ) and the Root Entry Zone (REZ) were adopted for the radiosurgical treatment of trigeminal neuralgia (TN), a more anterior target involving the Gasserian ganglion was used. Thanks to advancements in imaging technology, it is now possible to identify and target separate nerve divisions in Meckel’s Cave as desired. Although this approach has been mentioned previously, no clinical study has investigated it until now. This study aims to fill this gap in the literature.

Methods Trigeminal neuralgia patients who received radiosurgical treatment between February 2019 and June 2022 in a single centre were included in the study. Pain relief, medication dependency and side effect profiles of the investigated anterior selective target (AST) were compared to those of the classical targets at 1 week, 1–3-6 months, and 1 year.

Results A total of 66 patients were included in the study. Effectiveness, safety and application convenience parameters were compared between; the REZ (n = 21), RGZ (n = 20) and AST (n = 25) groups. All groups showed significant improvement in pain with similar results to each other. AST treatments were performed in significantly shorter beam-on-times and with significantly lower brainstem doses.

Conclusions The investigated AST showed comparable results to the classical targets without any indication of superiority or inferiority in terms of efficacy and safety in this preliminary investigation. As no blocks were needed to protect the brainstem with this method, it can be used for select patients as needed and could even be investigated in larger studies as an alternative approach.

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External assessment of preoperative scores for predicting outcome after microvascular decompression for trigeminal neuralgia

J Neurosurg 141:1056–1062, 2024

Recently, two scoring systems have been developed for predicting pain-free outcomes after microvascular decompression (MVD). Evaluation of these scores on large external datasets has been limited. In this study, the authors aimed to evaluate the performance of published MVD scoring systems in predicting pain-free outcome.

METHODS A total of 458 patients who underwent MVD for trigeminal neuralgia (TN) between 2007 and 2020 and had at least 6 months of follow-up were included in this study. Hardaway and Panczykowski scores were retrospectively computed for each patient and compared with postoperative pain recurrence and pain-free duration.

RESULTS The mean ± SD area under the receiver operating characteristic curve for predicting any pain recurrence after MVD was 0.567 ± 0.081 using the Hardaway score and 0.546 ± 0.085 using the Panczykowski score. On log-rank tests and Kaplan-Meier analysis, the patients with Hardaway scores of 0–2 had significantly shorter pain-free survival times after MVD than did those with a score of 3. Patients with a Panczykowski score of 1 had a significantly shorter pain-free duration after surgery compared with both patients with scores of 2–3 and patients with scores of 4–5. Patients with Panczykowski scores of 2–3 also had significantly shorter pain-free duration compared with patients with scores of 4–5.

CONCLUSIONS Both the Hardaway and Panczykowski scores may be useful for predicting postoperative pain-free duration in TN patients, and their utility may be greatest when scores are clustered. Continued refinement of both scoring systems will help to improve our ability to predict patient outcomes after MVD.

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Endoscopic Retrolabyrinthine Craniotomy for Exposure of the Trigeminal Nerve Root Entry Zone

Operative Neurosurgery 27:464–470, 2024

Exposure of the root entry zone (REZ) of the trigeminal nerve (TN) for microvascular decompression is commonly obtained with a retrosigmoid approach, with or without endoscopic assistance. We hypothesized that adequate exposure of the TN REZ could be obtained through an endoscopic retrolabyrinthine (RL) approach. We aim to quantify exposure of the REZ of the TN using endoscopic RL approach, with and without drilling of the suprameatal tubercle of the internal auditory canal.

METHODS: Surgical dissection was performed bilaterally on 3 embalmed cadaveric human heads at the anatomy laboratory of the House Institute. Heads were scanned for volumetric analysis using 3D Slicer software both before and after dissection. Extent of exposure was quantified in 2 ways: first, by assessment of the surgeon’s ability to visualize 16 predetermined anatomic landmarks with the endoscope and second, we estimated the “working” area by placing fiducials under the fully endoscopic view and calculating the resultant 3D volume.

RESULTS: Using the standard endoscopic RL approach, anaverageof 13.8 landmarks (range 12-16) was visualized. The estimated working volume exposed by the RL on each side of each head varied from 189.28 to 527.85 mm3 . Drilling of the suprameatal tubercle provided both increases in landmark visualization and, on average, an additional 55 mm 3 of working volume.

CONCLUSION: The endoscopic RL approach is a viable alternative to the standard retrosigmoid approach. Potential advantages of the RL include a more lateral trajectory that minimizes the need for cerebellar retraction and a shorter working distance and shallower angle to the cerebellopontine angle. Potential disadvantages include longer surgery time, increased technical difficulty of exposure, and potential for cerebrospinal fluid leak and or hearing loss.

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Preoperative Opioid Use and Postoperative Outcomes in Patients Undergoing Microvascular Decompression for Trigeminal Neuralgia

Neurosurgery 95:548–555, 2024

The prescription of opioid analgesics for trigeminal neuralgia (TN) is controversial, and their effect on postoperative outcomes for patients with TN undergoing microvascular decompression (MVD) has not been reported. We aimed to describe the relationship between preoperative opioid use and postoperative outcomes in patients with TN undergoing MVD.

METHODS: We reviewed the records of 920 patients with TN at our institution who underwent an MVD between 2007 and 2020. Patients were sorted into 2 groups based on preoperative opioid usage. Demographic information, comorbidities, characteristics of TN, preoperative medications, pain and numbness outcomes, and recurrence data were recorded and compared between groups. Multivariate ordinal regression, Kaplan–Meier survival analysis, and Cox proportional hazards were used to assess differences in pain outcomes between groups.

RESULTS: One hundred and forty-five (15.8%) patients in this study used opioids preoperatively. Patients who used opioids preoperatively were younger (P = .04), were more likely to have a smoking history (P < .001), experienced greater pain in modified Barrow Neurological Institute pain score at final follow-up (P = .001), and were more likely to experience pain recurrence (P = .01). In addition, patients who used opioids preoperatively were more likely to also have been prescribed TN medications including muscle relaxants and antidepressants preoperatively (P < .001 and P < .001, respectively). On multivariate regression, opioid use was an independent risk factor for greater postoperative pain at final follow-up (P = .006) after controlling for variables including female sex and age. Opioid use was associated with shorter time to pain recurrence on Kaplan–Meier analysis (P = .005) and was associated with increased risk for recurrence on Cox proportional hazards regression (P = .008).

CONCLUSION: Preoperative opioid use in the setting of TN is associated with worse pain outcomes and increased risk for pain recurrence after MVD. These results indicate that opioids should be prescribed cautiously for TN and that worse post-MVD outcomes may occur in patients using opioids preoperatively.

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Standard operating procedure and surgical technique innovation in fully endoscopic microvascular decompression for trigeminal neuralgia

Acta Neurochirurgica (2024) 166:351

Microvascular decompression (MVD) is a well-established and effective treatment for primary trigeminal neuralgia (TN). Endoscopy has been implemented to provide a comprehensive view of neurovascular conflict and minimizes the damages of brain retraction during MVD.

Objectives To preliminarily evaluate the surgical safety and efficacy of fully endoscopic microvascular decompression (EMVD) for primary TN with surgeon performing two-hand manipulation and assistant holding endoscope.

Methods Retrospective clinical analysis of 189 patients with primary TN underwent EMVD between June 2019 and August 2022 was performed. By analyzing the intraoperative situation, the outcomes of postoperative symptoms and the main complications, we evaluated the reliability and effectivity of the operative technique in the treatment of primary TN.

Results We summarized the standard operating procedure of EMVD for primary TN with surgeon performing two-hand manipulation and assistant holding endoscope. In addition, acicular bipolar electrocoagulation technique was developed to handle venous compression. During the follow-up period, good pain relief was achieved in 178 patients (94.2%) and recurrence of pain was observed in 4 patients (2.1%). Postoperative temporary complications included trigeminal dysesthesias (7 patients, 4.8%), cerebrospinal fluid leak (2 patients, 1.1%), hearing difficulty (3 patient, 1.6%), facial paresis (2 patients, 1.1%) and vertigo (5 patients, 2.7%). There were no cases of intracranial hemorrhage, cerebellar swelling and death.

Conclusion This EMVD technique is reliable and effective, and can be used as a routine surgical procedure for primary TN.

 

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Standard operating procedure and surgical technique innovation in fully endoscopic microvascular decompression for trigeminal neuralgia: technical note on 189 patients

Acta Neurochirurgica (2024) 166:351

Microvascular decompression (MVD) is a well-established and effective treatment for primary trigeminal neuralgia (TN). Endoscopy has been implemented to provide a comprehensive view of neurovascular conflict and minimizes the damages of brain retraction during MVD.

Objectives To preliminarily evaluate the surgical safety and efficacy of fully endoscopic microvascular decompression (EMVD) for primary TN with surgeon performing two-hand manipulation and assistant holding endoscope.

Methods Retrospective clinical analysis of 189 patients with primary TN underwent EMVD between June 2019 and August 2022 was performed. By analyzing the intraoperative situation, the outcomes of postoperative symptoms and the main complications, we evaluated the reliability and effectivity of the operative technique in the treatment of primary TN.

Results We summarized the standard operating procedure of EMVD for primary TN with surgeon performing two-hand manipulation and assistant holding endoscope. In addition, acicular bipolar electrocoagulation technique was developed to handle venous compression. During the follow-up period, good pain relief was achieved in 178 patients (94.2%) and recurrence of pain was observed in 4 patients (2.1%). Postoperative temporary complications included trigeminal dysesthesias (7 patients, 4.8%), cerebrospinal fluid leak (2 patients, 1.1%), hearing difficulty (3 patient, 1.6%), facial paresis (2 patients, 1.1%) and vertigo (5 patients, 2.7%). There were no cases of intracranial hemorrhage, cerebellar swelling and death.

Conclusion This EMVD technique is reliable and effective, and can be used as a routine surgical procedure for primary TN.

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Transposition versus interposition method in microvascular decompression for trigeminal neuralgia

J Neurosurg 140:1777–1784, 2024

Operative interposition of material between the trigeminal nerve and offending artery for surgical treatment of drug-resistant trigeminal neuralgia (TGN), following the Jannetta method, has been proven to be the most successful invasive treatment. Reexplorations of patients with recurrence of TGN have revealed nerve root irritations and scarring due to interposed material. To prevent these complications, modifications of microvascular decompression (MVD) aim at transposing the vessel away from the trigeminal nerve, without attachment of additional material to the nerve root. Given that both techniques (interposition and transposition) have been performed in the authors’ institution, they decided to analyze them for the short- and midterm outcomes.

METHODS All patients who had undergone MVD for drug-resistant TGN in the authors’ institution between 2008 and 2022 were analyzed retrospectively. Outcome at discharge and follow-up was evaluated using the Barrow Neurological Institute pain intensity score. Additionally, complications and pain recurrence were assessed.

RESULTS A total of 114 patients were operated on using transposition and 110 patients were treated using interposition. For transposition 102 patients were followed up for a median of 31.5 months, and for interposition 100 patients were followed up for a median of 95 months. At discharge 92.1% versus 94.5% of patients in the transposition and interposition groups, respectively, experienced a good outcome (Barrow Neurological Institute pain intensity scores I–III). At followup, 83.3% versus 85% of patients in the transposition and interposition groups, respectively, continued to demonstrate a good outcome. In 4.9% of patients in the transposition group and in 6% of patients in the interposition group, recurrence of pain occurred. Complications occurred in 24.6% of patients in the transposition and in 27.3% of those in the interposition group. The most frequent complications were facial hypesthesia (10.5% vs 11.8%, transposition vs interposition), followed by CSF leaks (2.6% vs 8.2%).

CONCLUSIONS Transposition for MVD is an elegant way of solving vessel-nerve conflicts at the cerebellopontine angle. Similar to interposition, transposition shows positive short- and midterm outcomes for patients experiencing drugresistant TGN. However, the main objective of transposition, which is improved prevention of recurrence and reduction of complications at the trigeminal nerve, could not be confirmed in this study.

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The relevance of biologically effective dose for pain relief and sensory dysfunction after Gamma Knife radiosurgery for trigeminal neuralgia: an 871-patient multicenter study

J Neurosurg 141:461–473, 2024

Recent studies have suggested that biologically effective dose (BED) is an important correlate of pain relief and sensory dysfunction after Gamma Knife radiosurgery (GKRS) for trigeminal neuralgia (TN). The goal of this study was to determine if BED is superior to prescription dose in predicting outcomes in TN patients undergoing GKRS as a first procedure.

METHODS This was a retrospective study of 871 patients with type 1 TN from 13 GKRS centers. Patient demographics, pain characteristics, treatment parameters, and outcomes were reviewed. BED was compared with prescription dose and other dosimetric factors for their predictive value.

RESULTS The median age of the patients was 68 years, and 60% were female. Nearly 70% of patients experienced pain in the V2 and/or V3 dermatomes, predominantly on the right side (60%). Most patients had modified BNI Pain Intensity Scale grade IV or V pain (89.2%) and were taking 1 or 2 pain medications (74.1%). The median prescription dose was 80 Gy (range 62.5–95 Gy). The proximal trigeminal nerve was targeted in 77.9% of cases, and the median follow-up was 21 months (range 6–156 months). Initial pain relief (modified BNI Pain Intensity Scale grades I–IIIa) was noted in 81.8% of evaluable patients at a median of 30 days. Of 709 patients who achieved initial pain relief, 42.3% experienced at least one pain recurrence after GKRS at a median of 44 months, with 49.0% of these patients undergoing a second procedure. New-onset facial numbness occurred in 25.3% of patients after a median of 8 months. Age ≥ 63 years was associated with a higher probability of both initial pain relief and maintaining pain relief. A distal target location was associated with a higher probability of initial and long-term pain relief, but also a higher incidence of sensory dysfunction. BED ≥ 2100 Gy 2.47 was predictive of pain relief at 30 days and 1 year for the distal target, whereas physical dose ≥ 85 Gy was significant for the proximal target, but the restricted range of BED values in this subgroup could be a confounding factor. A maximum brainstem point dose ≥ 29.5 Gy was associated with a higher probability of bothersome facial numbness.

CONCLUSIONS BED and physical dose were both predictive of pain relief and could be used as treatment planning goals for distal and proximal targets, respectively, while considering maximum brainstem point dose < 29.5 Gy as a potential constraint for bothersome numbness.

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Neurovascular Compression in Patients With Trigeminal Neuralgia May Be Associated With Worse Outcomes After Primary Percutaneous Rhizotomy

Neurosurgery 94:1072–1078, 2024

Percutaneous rhizotomy may be an effective primary intervention in patients with trigeminal neuralgia who are poor candidates for microvascular decompression or those who desire a less invasive approach. However, the influence of neurovascular compression on pain-free survival after primary percutaneous rhizotomy is not well understood.

METHODS: We retrospectively reviewed all patients undergoing percutaneous rhizotomy at our institution from 1995 to 2022. Patients were included if they had no history of surgical intervention, available preoperative MRI imaging, and postoperative follow-up data. Barrow Neurological Institute pain scores were assigned at various time points. We collected baseline patient information, pain characteristics, and perioperative complications for each patient. In addition, we recorded evidence of pain recurrence. Patients were dichotomized into those with evidence of neurovascular compression on preoperative MRI vs those without. The effect of neurovascular compression on pain-free survival was assessed using Kaplan-Meier Cox proportional hazards analyses.

RESULTS: Of the 2726 patients reviewed, 298 met our inclusion criteria. Our study comprised 261 patients with no evidence of neurovascular compression on preoperative MRI vs 37 patients with evidence of neurovascular compression on preoperative MRI. Patients in the compression group had a shorter median duration to recurrence compared with those in the no compression group, P = .01. Kaplan-Meier survival analysis revealed that patients with preoperative evidence of neurovascular compression on MRI imaging demonstrated shorter pain-free survival compared with those without such evidence [hazard ratio = 1.57 (1.03-2.4), P = .037]. Cox proportional hazards analysis demonstrated that evidence of neurovascular compression was associated with poor pain-free survival [hazard ratio = 1.64 (1.06-2.53), P = .03].

CONCLUSION: Patients with neurovascular compression on preoperative MRI may experience reduced time to recurrence compared with those without after percutaneous rhizotomy. These patients should be counseled on potential reduced efficacy of percutaneous rhizotomy as a primary intervention for their pain.

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Retrogasserian trigeminal radiofrequency‑thermorhizotmoy for trigeminal neuralgia

Acta Neurochirurgica (2024) 166:209

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.

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Anatomic Variations of Foramen Ovale as a Predictor of Successful Cannulation in Percutaneous Trigeminal Rhizotomies

Operative Neurosurgery 26:279–285, 2024

Percutaneous trigeminal rhizotomies are common treatment modalities for medically refractory trigeminal neuralgia (TN). Failure of these procedures is frequently due to surgical inability to cannulate the foramen ovale (FO) and is thought to be due to variations in anatomy. The purpose of this study is to characterize the relationships between anatomic features surrounding FO and investigate the association between anatomic morphology and successful cannulation of FO in patients undergoing percutaneous trigeminal rhizotomy.

METHODS: A retrospective analysis was conducted of all patients undergoing percutaneous trigeminal rhizotomy for TN at our academic center between January 1, 2010, and July 31, 2022. Preoperative 1-mm thin-cut computed tomography head imaging was accessed to perform measurements surrounding the FO, including inlet width, outlet width, interforaminal distance (a representation of the lateral extent of FO along the middle fossa), and sella–sphenoid angle (a representation of the coronal slope of FO). Mann–Whitney U tests assessed the difference in measurements for patients who succeeded and failed cannulation.

RESULTS: Among 37 patients who met inclusion criteria, 34 (91.9%) successfully underwent cannulation. Successful cannulation was associated with larger inlet widths (median = 5.87 vs 3.67 mm, U = 6.0, P = .006), larger outlet widths (median = 7.13 vs 5.10 mm, U = 14.0, P = .040), and smaller sella–sphenoid angles (median = 52.00°vs 111.00°, U = 0.0, P < .001). Interforaminal distances were not associated with the ability to cannulate FO surgically.

CONCLUSION: We have identified morphological characteristics associated with successful cannulation in percutaneous rhizotomies for TN. Preoperative imaging may optimize surgical technique and predict cannulation failure.

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The Sagittal Angle of the Trigeminal Nerve at the Porus Trigeminus is a Radiologic Predictor of Surgical Outcome in Microvascular Decompression for Classical Trigeminal Neuralgia

Neurosurgery 94:524–528, 2024

Classical trigeminal neuralgia (cTN) is a painful disease. Microvascular decompression (MVD) provides immediate and durable relief in many patients. A variety of positive and negative prognostic biomarkers for MVD have been identified. The sagittal angle of the trigeminal nerve at the porus trigeminus (SATNaPT) is an MRI biomarker that can identify a subset of patients with cTN whose trigeminal nerve anatomy is different from normal controls. The purpose of this case-control study was to determine whether an abnormally hyperacute SATNaPT is a negative prognostic biomarker in patients with cTN undergoing MVD.

METHODS: Preoperative MRIs from 300 patients with cTN who underwent MVD were analyzed to identify patients with a hyperacute SATNaPT (defined as less than 3 SDs below the mean). The rate of surgical success (pain-free after at least 12 months) was compared between patients with a hyperacute SATNaPT and all other patients.

RESULTS: Patients without a hyperacute SATNaPT had an 82% likelihood of surgical success, whereas patients with a hyperacute SATNaPT had a 58% likelihood of surgical success (P < .05). Patients with a hyperacute SATNaPT who also had no evidence of vascular compression on preoperative MRI had an even lower likelihood of success (29%, P < .05).

CONCLUSION: In patients with cTN being considered for MVD, a hyperacute SATNaPT is a negative prognostic biomarker that predicts a higher likelihood of surgical failure. Patients with a hyperacute SATNaPT, particularly those without MRI evidence of vascular compression, may benefit from other surgical treatments or a modification of MVD to adequately address the underlying cause of cTN.

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Management outcomes of peripontine arteriovenous malformation patients presenting with trigeminal neuralgia

J Neurosurg 140:515–521, 2024

Trigeminal neuralgia as the presenting symptom of brain arteriovenous malformation (bAVM) has been rarely reported. Treatment of reported cases has been skewed toward surgery for these scarce, deeply located bAVMs. Here, the authors report their management and outcomes of bAVM patients presenting with ipsilateral trigeminal neuralgia (TN) at their institution.

METHODS This is a retrospective cohort study. The authors’ institutional bAVM database was queried for non–hereditary hemorrhagic telangiectasia bAVMs in pontine, cistern, brainstem, trigeminal nerve, or tentorial locations. Patients with complete data were included in a search for trigeminal neuralgia or “facial pain” as the presenting symptom with TN being on the same side as the bAVM. Demographics, TN and bAVM characteristics, management strategies, and outcomes of bAVM and TN management were analyzed.

RESULTS Fifty-seven peripontine bAVMs were identified; 8 (14.0%) of these bAVMs were discovered because of ipsilateral TN, including 4 patients (50%) with facial pain in the V2 distribution. Five patients (62.5%) were treated with carbamazepine as the initial medical therapy, 2 (25%) underwent multiple rhizotomies, and 1 (12.5%) underwent microvascular decompression. None of the patients with TN-associated bAVMs presented with hemorrhage, compared with 25 patients (51%) with bAVMs that were not associated with TN (p < 0.01). TN-associated bAVMs were overall smaller than non–TNassociated bAVMs, but the difference was not statistically significant (1.71 cm vs 2.22 cm, p = 0.117), and the SpetzlerMartin grades were similar. Six patients (75%) underwent radiosurgery to the bAVM (mean dose 1800 cGy, mean target volume 0.563 cm 3 ) and had complete resolution of TN symptoms (100%). The mean time from radiosurgery to TN resolution was 193 (range 21–360) days, and 83.3% of treated TN-associated bAVMs were obliterated via radiosurgery. Two patients (12.5%) were recommended for conservative management, with one undergoing subsequent rhizotomies and another patient died of hemorrhage during follow-up.

CONCLUSIONS TN-associated bAVM is a rare condition with limited evidence for management guidance. Radiosurgery can be safe and effective in achieving durable TN control in patients with TN-associated bAVMs. Despite their deep location and unruptured presentation, obliteration can reach 83.3% with radiosurgery.

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Clival-Meckel’s Cave Angle: A Predictor of Glycerol Displacement in Percutaneous Glycerol Rhizotomy for Trigeminal Neuralgia

Operative Neurosurgery 26:141–148, 2024

Percutaneous glycerol rhizotomy successfully treats trigeminal neuralgia although failure rates and durability of the procedure are variable. Some of this variability in clinical outcome might be due to egress of glycerol from Meckel’s cave (MC) because of surgical positioning and individual patient anatomy. In this article, we quantitatively analyzed the anatomic variances that affect glycerol fluid dynamics to better predict patients more amenable for percutaneous glycerol injections.

METHODS: Computed tomography imaging of 11 cadaveric heads was used to calculate bilateral Clival-Meckel’s cave (CMC) and sella-temporal (ST) angles. Twenty-two cadaveric percutaneous injections of dyed glycerol into the Meckel’s cave were performed using H¨artel’s approach, and the fluid movement was documented at prespecified intervals over 1 hour. The relationship between the angles and glycerol migration was studied.

RESULTS: Specimens with basal cistern involvement by 60 minutes had significantly greater CMC angles (median [IQR]: basal cistern involvement = 74.5°[59.5°-89.5°] vs no basal cistern involvement = 58.0°[49.0°-67.0°]), U = 6.0, P < .001. This model may predict which patients will experience glycerol migration away from the Gasserian ganglion (area under the curve: 0.950, SE: 0.046, CI: 0.859-1.041, P < .001). Increased ST angle was associated with lateral flow of glycerol (r s = 0.639, P = .001), and CMC angle was associated with total area of dispersion (r s = À0.474, P = .026).

CONCLUSION: Anatomic variation in skull base angles affects glycerol migration. Specifically, a more obtuse CMC angle was associated with a higher risk of posterior migration away from the Gasserian ganglion. This may be a reason for differing rates of surgical success. These results suggest that anterior head flexion for 60 minutes may prevent percutaneous glycerol rhizotomy failures and some patients with large CMC angles are more likely to benefit from postinjection head positioning. However, this clinical effect needs validation in vivo.

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Radiofrequency thermocoagulation under neuromonitoring guidance and general anesthesia for treatment of refractory trigeminal neuralgia

Acta Neurochirurgica (2024) 166:56

Radiofrequency thermocoagulation (RFT) for refractory trigeminal neuralgia is usually performed in awake patients to localize the involved trigeminal branches. It is often a painful experience. Here, we present RFT under neuromonitoring guidance and general anesthesia.

Method Stimulation of trigeminal branches at the foramen ovale with the tip of the RFT cannula is performed under short general anesthesia. Antidromic sensory–evoked potentials (aSEP) are recorded from the 3 trigeminal branches. The cannula is repositioned until the desired branch can be stimulated and lesioned.

Conclusion aSEP enable accurate localization of involved trigeminal branches during RFT and allow performing the procedure under general anesthesia.

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Repeat Gamma Knife radiosurgery for recurrent trigeminal neuralgia in patients with multiple sclerosis

Acta Neurochirurgica (2024) 166:15

Gamma Knife radiosurgery (GKRS) has emerged as an effective treatment option for trigeminal neuralgia (TN) in patients with multiple sclerosis (MS). To date, the outcomes of repeat GKRS for patients with TN and MS with recurrent pain have been investigated in a few patients. This study aims to report the outcomes and predictive factors of pain reduction for MS patients undergoing repeat GKRS for recurrent TN.

Methods Eighteen patients with MS underwent repeat GKRS for recurrent TN. A retrospective chart review and telephone interviews were conducted to determine background medical history, dosimetric data, and outcomes of the procedure. Facial pain and sensory function were evaluated using the Barrow Neurological Institute (BNI) scales.

Results Fifteen patients achieved a BNI pain score of IIIa or better, indicating pain reduction, within a median period of 21 days after repeat GKRS. The maximum dose for repeat GKRS ranged from 70 to 85 Gy. Pain recurred in 5 patients after a median period of 12 months after GKRS. Percentages of patients with pain reduction at 1, 2, 3, 5, and 7 years were 60%, 60%, 50%, 50%, and 50%, respectively. Older age at repeat GKRS predicted sustained pain reduction (P = 0.01). Seven patients developed facial sensory disturbances, which were bothersome in two patients.

Conclusions Repeat GKRS may be used as an effective treatment modality for prolonging the duration of pain reduction time in patients with MS and TN. After repeat GKRS, facial sensory disturbances are common; however, they are often not bothersome.

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