Category: Pain

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How to deal with the superior petrosal vein in microvascular decompression for trigeminal neuralgia?

Neurosurg Focus 59(3):E12, 2025

Sectioning the superior petrosal vein at its main trunk while maintaining venous crossflow is a safe and effective strategy during microvascular decompression for trigeminal neuralgia, improving surgical access without significantly increasing venous-related complications, according to a large retrospective study.

• Management of the superior petrosal vein (SPV) during microvascular decompression (MVD) for trigeminal neuralgia (TN) is controversial, with concerns about operative field access and potential complications.

• A retrospective study evaluated a technique of SPV division at its main trunk near the superior petrosal sinus, maintaining venous crossflow through contributories, in 171 out of 217 patients (79%).

• No statistically significant increase in venous-related complications was observed in the SPV division group compared to the preservation group.

• Only 3 possibly venous-related complications occurred in the SPV division group, all of which were mild and transient.

• Anatomical variations of the SPV require careful intraoperative assessment and preservation of collateral venous drainage for safety.

• Preoperative imaging and intraoperative techniques (e.g., indocyanine green angiography) are recommended to assess collateral flow before SPV division.

• The study concludes that SPV division at the main trunk with preservation of crossflow is a safe strategy that improves surgical exposure during MVD for TN.

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Trigeminal neuralgia or hemifacial spasm due to vertebrobasilar dolichoectasia

Neurosurg Focus 59(3):E6, 2025

Microvascular decompression (MVD) is the most effective treatment for trigeminal neuralgia and hemifacial spasm caused by vertebrobasilar dolichoectasia, offering higher symptom resolution and lower recurrence than radiosurgery or medication. Endoscope-assisted MVD reduces complications. Interposition and transposition surgical techniques show similar efficacy and recurrence rates.

• Vertebrobasilar dolichoectasia (VBD) is a rare vascular disorder that can compress cranial nerves, most commonly causing trigeminal neuralgia (TN) and hemifacial spasm (HFS).

• Microvascular decompression (MVD) is the most effective treatment, achieving symptom resolution in 87.3% of cases and having the lowest recurrence rate (6.5%) compared to radiosurgery and medication.

• Radiosurgery offers symptom relief in 63.7% of patients but has a high recurrence rate (47.2%) and is mainly used when surgery is contraindicated.

• Endoscope-assisted MVD significantly reduces complication rates (5.3% vs 23.8% with microscope) but does not improve symptom resolution compared to microscope-assisted surgery.

• Interposition and transposition techniques for nerve decompression show similar efficacy and recurrence rates, with no significant differences in complications.

• Nonsurgical treatments (medication, botulinum toxin, etc.) rarely result in full symptom resolution and are generally insufficient as standalone therapies.

• Multiple vessels (AICA, PICA, SCA) can be involved in nerve compression in VBD, affecting surgical planning and outcomes.

• Most patients experience long delays (mean 4–4.5 years) before diagnosis, and VBD-related cranial neuropathies remain challenging to manage due to anatomical complexity and limited high-quality evidence.

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Validation of Härtel Surface Anatomical Landmarks for Locating the Foramen Ovale: A Computed Tomography Scan Analysis and Revised Technique Description

Operative Neurosurgery 29:399–407, 2025

CT-based validation of Hartel’s anatomical landmarks shows the foramen ovale is closer to the tragus and more medial than previously described. Revised needle trajectories, targeting 2–2.5 cm anterior to the tragus and between the inner canthus and midpupillary lines, may improve safety and accuracy in trigeminal procedures.

• Hartel surface anatomical landmarks for foramen ovale (FO) localization were assessed using CT scans in 99 adults (198 foramina).

• The FO is typically closer to the external auditory canal (mean 23.26 mm) and more medial (mean 25.43 mm from midline) than Hartel’s original description.

• FO is usually located between the eye’s inner canthus (IC) and midpupillary (MP) lines, not directly along the MP line as previously thought.

• Recommended needle trajectory: 2–2.5 cm anterior to tragus and targeting a point between the IC and MP lines, avoiding excessive medial/posterior displacement.

• A posteromedial “Danger Zone” exists within 20 mm of the midline and EAC, where vascular injury risk increases.

• Imaging guidance (fluoroscopy, CT) remains essential for safe and accurate needle navigation.

• These adjustments may improve procedural accuracy, safety, and patient outcomes for percutaneous trigeminal procedures.

• Further clinical and cadaveric validation is needed for these technique modifications.

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Perioperative Evaluation and Monitoring of Percutaneous Balloon Compression in Treatment of Trigeminal Neuralgia

Operative Neurosurgery 29:263–270, 2025

This prospective study found that higher intraluminal balloon pressure during percutaneous balloon compression for trigeminal neuralgia reduces long-term pain recurrence without increasing persistent facial numbness. Preoperative MRI-based Meckel’s cave assessment and intraoperative pressure monitoring help optimize outcomes and balance pain relief with sensory side effects.

• Percutaneous balloon compression (PBC) is used to treat trigeminal neuralgia (TN), with outcomes influenced by intraluminal balloon pressure, balloon volume, and Meckel’s cave volume.

• Preoperative high-resolution MRI enables 3D reconstruction of Meckel’s cave, aiding in predicting intraoperative balloon volume.

• Intraoperative monitoring of balloon pressure and volume was performed in 37 patients; primary outcomes were facial numbness and pain recurrence up to 24 months.

• Facial numbness was common in the first month (38%), but typically resolved by 24 months; numbness was not linked to balloon pressure.

• TN recurrence rate was about 25% at 24 months and was significantly associated with lower intraluminal balloon pressure.

• No significant differences in Meckel’s cave or balloon volume were observed between subgroups, but Meckel’s cave volume correlated positively with balloon volume.

• Authors recommend maintaining intraluminal balloon pressure around 135.7 ± 27.1 kPa (with 120 seconds compression) to minimize recurrence without increasing sensory deficits.

• Perioperative assessment of balloon compression (including MRI and pressure monitoring) is feasible and may help balance TN recurrence risk and sensory complications.

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Neuroapraxia of Trigeminal Nerve Controlled by Neuromonitoring During Microvascular Decompression in Multiple Sclerosis Patients Affected by Drug-Resistant Trigeminal Neuralgia Recurrent After Previous Operations

Operative Neurosurgery 29:295–300, 2025

This case series reports the first use of intraoperative neuromonitoring-controlled neuroapraxia of the trigeminal nerve with a temporary aneurysm clip during microvascular decompression for drug-resistant, recurrent trigeminal neuralgia in multiple sclerosis patients, showing immediate pain relief and no complications at up to 10 months’ follow-up.

• Trigeminal neuralgia (TN) in multiple sclerosis (MS) patients is difficult to treat and often recurs after surgery.

• This report describes the first 3 cases of recurrent, drug-resistant MS-related TN treated with intraoperative neuromonitoring (IONM)-controlled neuroapraxia during microvascular decompression (MVD).

• Neuroapraxia was induced by applying a temporary titanium aneurysm clip to the trigeminal nerve for up to 30 seconds, with real-time IONM to avoid nerve damage.

• All patients achieved immediate pain relief and maintained Barrow Neurological Institute pain score I at 9–10 months follow-up, with no major complications.

• Compared to previous techniques, this approach minimized complications by reducing clip time and using neuromonitoring.

• This technique may offer a safe, promising option for MS patients with recurrent TN, but larger studies with longer follow-up are needed.

• The study’s main limitation is the small patient number and short follow-up period.

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The efficacy of combining pulsed radiofrequency with low-temperature continuous radiofrequency for the treatment of primary trigeminal neuralgia

J Neurosurg 143:100–110, 2025

High-voltage pulsed radiofrequency (PRF) combined with low-temperature continuous radiofrequency (CRF) significantly improved 12-month response rates and pain scores in primary trigeminal neuralgia compared to PRF alone, with minimal complications. This combined approach offers a promising alternative for patients unresponsive to medication.

High-voltage pulsed radiofrequency (PRF) combined with low-temperature (60°C) continuous radiofrequency (CRF) was compared to high-voltage PRF alone for treating primary trigeminal neuralgia (TN) in a randomized controlled trial.

• 146 patients were randomized to either PRF+CRF or PRF alone, with 12-month response rate as the primary outcome.

• The PRF+CRF group had a significantly higher response rate at 12 months (83.6% vs 67.1%, p = 0.021) and better pain relief at all measured time points.

• Patient satisfaction scores were higher in the PRF+CRF group at 1, 6, and 12 months.

• Facial numbness and masseter muscle weakness were more frequent in the PRF+CRF group but were mild and resolved within months; no serious complications occurred.

• Both treatments were safe, with no cases of anesthesia dolorosa, corneal anesthesia, or keratitis.

• The study was limited by single-center design, open-label nature, and a smaller than expected difference in primary outcome, suggesting the need for larger studies.

• Conclusion: High-voltage PRF combined with low-temperature CRF offers better pain control and satisfaction than PRF alone, with minimal side effects, for patients with refractory TN.

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Stratifying trigeminal neuralgia and characterizing an abnormal property of brain functional organization: a resting-state fMRI and machine learning study

J Neurosurg 143:74–82, 2025

Resting-state fMRI and machine learning revealed distinct brain connectivity and activity differences between classical and idiopathic trigeminal neuralgia (TN) and controls. These findings identify potential neuroimaging biomarkers for TN subtypes, aiding diagnosis and understanding of TN pathophysiology.

Primary trigeminal neuralgia (TN) includes classical (CTN) and idiopathic (ITN) types, sharing clinical features but differing in neurovascular compression (NVC) presence.

• Resting-state fMRI and machine learning were used to analyze brain functional connectivity and spontaneous activity in 50 TN patients (28 CTN, 22 ITN) and 43 controls.

• TN patients showed increased connectivity between the medial prefrontal cortex (mPFC) and left planum temporale, and decreased connectivity between mPFC and left superior frontal gyrus.

• CTN patients had further reduced connectivity between the left insula and left occipital pole, and decreased activity in the right temporal pole compared to ITN.

• TN patients exhibited heightened neural activity in frontal regions compared to controls.

• Machine learning (support vector machine) distinguished TN patients from controls with moderate accuracy (AUC 0.80).

• Findings suggest potential fMRI biomarkers for TN subtypes, aiding understanding of pathophysiology and improving diagnosis.

• Study limitations include small sample size and exclusion of bilateral/secondary TN, warranting further research.

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Effects of the length of preoperative conservative management on postoperative outcomes after primary microvascular decompression for trigeminal neuralgia

J Neurosurg 143:92–99, 2025

Prolonged preoperative conservative management with anticonvulsants in trigeminal neuralgia is associated with worse pain outcomes and higher pain recurrence after microvascular decompression. Early surgical intervention may improve postoperative results and reduce pain recurrence risk in these patients.

• Longer duration of preoperative conservative management (anticonvulsant use) before microvascular decompression (MVD) for trigeminal neuralgia (TN) is linked to worse postoperative pain outcomes and higher risk of pain recurrence.

• Median duration of conservative management before surgery was 1.74 years.

• Patients with longer conservative management had higher final BNI pain scores and greater rates of pain recurrence than those with shorter management.

• Longer conservative management predicted shorter pain-free survival after MVD.

• Younger age and longer conservative management duration were independent predictors of worse postoperative pain and recurrence.

• No significant difference in preoperative pain scores between groups; both had high pain levels pre-surgery.

• Findings suggest early surgical intervention may benefit TN patients who are candidates for MVD.

• Study was retrospective and single-institution, limiting generalizability; further research is needed.

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Deep learning–based segmentation of the trigeminal nerve and surrounding vasculature in trigeminal neuralgia

J Neurosurg 143:83–91, 2025

This study developed and validated deep learning U-Net models for automated 3D segmentation of the trigeminal nerve and surrounding vasculature in MRI of trigeminal neuralgia patients, enabling objective quantification of neurovascular conflict features and potentially improving preoperative evaluation and treatment planning.

• Deep learning (U-Net) models were used to segment the trigeminal nerve and surrounding vasculature in patients with trigeminal neuralgia using high-resolution CISS MRI.

• Six U-Net variants with different encoder backbones were tested; SE-ResNet50 performed best overall (Dice score = 0.775, IoU = 0.681).

• The models quantified anatomical features such as the surface area of neurovascular contact and distance to the contact point, showing no significant difference from manual segmentations.

• The best model achieved 100% sensitivity and specificity in detecting neurovascular conflict in the testing set.

• Automated 3D segmentation allows for objective, quantitative evaluation, improving on subjective and time-intensive manual methods.

• Limitations include inability to distinguish vessel type (artery vs. vein) and data from a single institution; future work should address these.

• The method may help standardize neurovascular conflict assessment and improve treatment selection for trigeminal neuralgia.

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Nervus intermedius sectioning for the treatment of geniculate neuralgia

J Neurosurg 143:111–118, 2025

Nervus intermedius (NI) sectioning for geniculate neuralgia (GN) provided pain relief in 81% and complete resolution in 68% of cases, with low complication rates. Combining NI sectioning with microvascular decompression improved outcomes. The study supports NI sectioning as a safe, effective surgical option when medical management fails.

• Geniculate neuralgia (GN) is a rare facial pain syndrome with severe stabbing ear pain, often involving the nervus intermedius (NI) as the primary structure.

• Medical management is first-line, but when ineffective, surgical options like NI sectioning and microvascular decompression (MVD) are considered.

• This study presents the largest case series (47 procedures in 45 patients) of NI sectioning for GN, with most patients also having trigeminal neuralgia or glossopharyngeal neuralgia.

• NI sectioning led to pain improvement (BNI score < IV) in 80.9% and complete pain resolution (BNI I) in 68.1% of procedures at latest follow-up.

• Combining NI sectioning with MVD further improved outcomes, especially in patients with concurrent neuralgias.

• Complications were rare: 2 cases of hearing loss, 1 confirmed permanent vestibular dysfunction, and 3 cases of loss of taste; no permanent facial paralysis or loss of lacrimation.

• Older age predicted worse pain outcomes after surgery.

• The study supports NI sectioning as a safe and effective treatment for GN, especially when tailored with MVD as needed.

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Designing and clinical application of a 3D-printed personalized model of a radiofrequency needle guide with a maxillary fixator for puncture of the gasserian ganglion for trigeminal neuralgia treatment

J Neurosurg 142:1256–1262, 2025

The study presents a 3D-printed personalized model (3D PPM) for radiofrequency needle guidance in trigeminal neuralgia treatment, reducing radiation exposure and pain during procedures. It showed effectiveness in controlled needle insertion and minimized postoperative complications compared to traditional methods.

• A 3D-printed personalized model (3D PPM) of a radiofrequency needle guide with a maxillary fixator was designed for gasserian ganglion puncture in trigeminal neuralgia treatment.

• 3D PPM reduces radiation exposure and pain during needle insertion, and minimizes postoperative complications.

• The study found that the use of 3D PPM significantly decreased radiation time and dose area product compared to traditional methods.

• Pain severity during the procedure was less in patients using 3D PPM, with more reporting mild pain compared to those not using it.

• Cheek swelling was less frequent in the group using 3D PPM, though not statistically significant due to small sample size.

• The 3D PPM enhances the accuracy of needle insertion and reduces radiation exposure, making it beneficial for less experienced neurosurgeons.

• Limitations include the unsuitability for patients with metal dental implants or missing teeth due to fixation issues.

• Despite limitations, the study shows promising results for 3D PPM in radiofrequency therapy of the gasserian ganglion, suggesting further research is needed.

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Revisiting Härtel’s technique for percutaneous transoval glycerol injection

Acta Neurochirurgica (2025) 167:126

The study revisits Härtel’s technique for percutaneous transoval glycerol injection in treating trigeminal neuralgia. It identifies an optimal entry point in the cheek, 2 mm below the horizontal plane, to improve procedural success and reduce complications, emphasizing the importance of precise needle guidance.

• Purpose: The study revisits Härtel’s technique for percutaneous transoval glycerol injection (GI) to treat trigeminal neuralgia, aiming to identify optimal needle entry points and trajectories using imaging-based simulations.

• Methods: CT and MRI-based simulations were conducted on eleven patients to determine optimal entry points and trajectories through the foramen ovale (FO) to reach Meckel’s cave.

• Findings: The optimal entry point is 2 mm below the horizontal plane through the angle of the mouth, providing better access to Meckel’s cave in most cases.

• Conclusion: Technical results of GI can be improved by selecting the optimal entry point and guiding the needle through the medial part of FO under fluoroscopy.

• Historical Context: Härtel’s technique, developed in 1912, provided a systematic approach to reach the trigeminal ganglion through FO.

• Variability in Techniques: Different variations of GI techniques have led to variable outcomes, highlighting the importance of standardizing the procedure.

• Simulation Insights: 3D simulations help in identifying reliable entry points and can be useful in cases with anatomical variations.

• Clinical Implications: The study suggests that lowering the entry point in the cheek could improve the success rate of GI procedures.

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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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The correlation study between posterior fossa crowding and classical trigeminal neuralgia

Acta Neurochirurgica (2025) 167:14

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.

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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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Technical report on intra-operative trigeminal root mapping in percutaneous lesioning for trigeminal neuralgias

Acta Neurochirurgica (2024) 166:434

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.

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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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