Category: Pain

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Hemodynamic parameters as biomarkers for predicting microvascular decompression efficacy in classic trigeminal neuralgia

J Neurosurg 145:36–44, 2026

This clinical study evaluates hemodynamic parameters derived from computational fluid dynamics (CFD) to predict microvascular decompression (MVD) efficacy in patients with classic trigeminal neuralgia (CTN). Using preoperative MR angiography and CFD, the authors compared PSF, PSPD, maximum WSS, and OSI between effective and ineffective MVD cohorts and developed logistic models to forecast surgical outcomes.

Results show lower peak systolic flow (PSF) and higher PSPD, maximum WSS, and OSI in effective cases; PSF and maximum WSS emerged as independent predictors. The best predictive model achieved AUC 0.920 with 90% sensitivity and specificity, supporting integration of hemodynamic metrics into preoperative decision-making for personalized CTN treatment.

Objective Evaluate whether CFD-derived hemodynamic parameters can predict microvascular decompression (MVD) efficacy in classic trigeminal neuralgia (CTN).

Design/participants 56 unilateral CTN patients (May 2022–Dec 2023) split into 28 effective vs 28 ineffective MVD outcomes; effectiveness defined as VAS pain score dropping to 0 on postoperative day 1, while ineffectiveness meant pain persisted (>0) through 3 months.

Workflow Use preoperative time-of-flight MR angiography to identify the neurovascular compression (NVC) zone, reconstruct the offending vessel segment, and run CFD to quantify PSF, PSPD, WSS, and OSI.

Key group differences Effective MVD associated with lower PSF (0.202 vs 0.306 ml/sec) and higher PSPD, maximum WSS, and OSI in the NVC zone (all statistically significant).

Independent predictors PSF and maximum WSS remained significant predictors of MVD efficacy in multivariable logistic regression.

Prediction performance A backward-selection logistic model achieved AUC 0.920 with 90% sensitivity and 90% specificity for predicting MVD efficacy.

Clinical interpretation Hemodynamic patterns consistent with higher vascular resistance/adverse shear environment at effective NVC sites, supporting use of CFD metrics to distinguish effective vs ineffective NVC.

Implication Integrating hemodynamic parameters (especially PSF and maximum WSS) could guide personalized treatment selection and improve preoperative prediction of MVD benefit.

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Repeat gamma knife radiosurgery for recurrent trigeminal neuralgia

Acta Neurochirurgica (2026) 168:143

This systematic review and meta-analysis evaluates outcomes after repeat Gamma Knife radiosurgery (GKRS) for recurrent trigeminal neuralgia, pooling data from 21 studies comprising 2,020 retreatments. It quantifies efficacy (BNI I–III favourable pain control ~77% after retreatment, 62% at long-term follow-up) and recurrence (~29%), and reports complication rates, notably facial hypoesthesia (~39%).

The paper follows PRISMA and Cochrane guidance, performs single-arm GLMM meta-analyses, sensitivity checks, and meta-regressions that found no consistent predictors of outcome. Limitations include retrospective series, moderate–severe bias, substantial heterogeneity, and variable dosimetry and reporting; prospective standardized studies are recommended.

Clinical context Trigeminal neuralgia causes intense, episodic, shock-like facial pain; Gamma Knife radiosurgery (GKRS) is used for medically refractory cases, and recurrence after initial GKRS can prompt consideration of repeat GKRS.

Study design Systematic review and meta-analysis conducted under PRISMA guidance; included English-language studies of patients needing repeat GKRS after inadequate response to medications and/or a single GKRS, with ≥12 months follow-up.

Evidence base 21 studies were included, comprising 2,486 initially treated patients and 2,020 undergoing repeat GKRS; most were female, median ages ranged 54.5–79.6 years, and ~85% were idiopathic trigeminal neuralgia.

Treatment patterns Most repeat procedures targeted the trigeminal root entry zone (REZ), typically using 70–80 Gy marginal doses; intervals between procedures varied widely (5–138 months; median ≈36 months).

Effectiveness Pain relief after repeat GKRS commonly occurred in ~70–90% of patients with typical improvement in BNI pain scores (often IV–V to I–IIIb); pooled favourable pain control (BNI I–III) after the latest treatment was 76.68%.

Durability & recurrence Median follow-up ranged 14–74 months; recurrence after repeat GKRS was reported around 10–35% (pooled recurrence 29.07%), and favourable pain control at last follow-up decreased to 61.94%.

Safety profile Facial sensory disturbances were frequent (reported 20–45%; pooled facial hypoesthesia 39.04%); bothersome dysesthesias and anesthesia dolorosa were uncommon (<3%).

Predictors/heterogeneity Meta-regression found no significant association between pain relief and age, pain duration, interval since prior GKRS, or dose, with substantial inter-study heterogeneity persisting.

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Hybrid fluoroscopy–neuronavigation technique for percutaneous balloon compression in trigeminal neuralgia

Acta Neurochirurgica (2026) 168:110

This article presents a hybrid fluoroscopy–electromagnetic neuronavigation technique for percutaneous balloon compression in trigeminal neuralgia, detailing preoperative CT trajectory planning, intraoperative dual guidance, and practical steps to optimize foramen ovale cannulation. Emphasis is placed on safety measures, anesthesia considerations, and procedural specifics such as entry point, stylet use, and balloon inflation parameters.

The manuscript discusses candidate selection, advantages for elderly or comorbid patients, limitations including equipment needs and limited evidence, and practical tips to minimize complications. Key points summarize indications, procedural timing, anatomical landmarks, and the hybrid approach’s potential to shorten the learning curve for junior surgeons.

Purpose: Hybrid fluoroscopy + electromagnetic neuronavigation improves accuracy and safety of foramen ovale cannulation for percutaneous balloon compression in trigeminal neuralgia, reducing multiple passes in anatomically variable cases

Planning: Preoperative thin-slice CT is used to design an individualized needle trajectory to the foramen ovale, sometimes modifying the classical Hartel entry point to avoid bony collision

Anesthesia: Performed under general anesthesia because trigeminal ganglion manipulation can trigger a vagal reflex causing severe bradycardia/asystole; atropine readiness is required

Setup & entry: Patient supine with slight head extension; entry point is typically ~2.5 cm lateral to the oral commissure, with neuronavigation confirming the skin site/trajectory and C-arm fluoroscopy providing real-time position checks

Needle guidance: Needle advanced under fluoroscopy toward the petrous ridge–clivus junction (lateral view alignment), then an electromagnetic sensor/stylet is inserted to confirm and fine-tune alignment with the preplanned path before FO passage

Balloon step: After cannulation, a 4F Fogarty balloon is inflated with ~0.75 ml iopamidol to achieve the characteristic pear-shaped configuration under fluoroscopy

Compression time: Balloon compression is maintained for ~1–3 minutes to balance pain relief with risks such as hypoesthesia and masticatory weakness; limit to a maximum of 3 minutes

Clinical role & limits: Useful for medication-refractory TN, especially elderly/comorbid patients or when MRI shows no neurovascular conflict; limitations include added cost/skill needs and low evidence base (lack of randomized trials)

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The utility of partial sensory rhizotomy and adjunct procedures in the surgical management of trigeminal neuralgia secondary to multiple sclerosis

J Neurosurg 144:1145–1153, 2026

This clinical study evaluates long-term outcomes of partial sensory rhizotomy (PSR) for trigeminal neuralgia (TN) secondary to multiple sclerosis (MS), comparing PSR alone, redo PSR, and PSR combined with microvascular decompression (MVD) or internal neurolysis (IN). Retrospective analysis of 37 procedures in 30 patients shows high immediate pain relief (89.2%), mean recurrence at 1.64 years, and variable durability across groups.

At final follow-up, combination therapy (PSR+MVD or PSR+IN) trended toward superior sustained pain freedom without increased complications, while first PSR commonly required additional interventions. The authors conclude PSR is an effective salvage option and suggest adjunctive MVD or IN may improve long-term outcomes, recommending prospective validation.

Objective Evaluate long-term outcomes of partial sensory rhizotomy (PSR) alone versus PSR combined with microvascular decompression (MVD) or internal neurolysis (IN) for trigeminal neuralgia secondary to multiple sclerosis.

Methods Retrospective review of PSR cases (2012–2023) grouped as first PSR, redo PSR, PSR+MVD, and PSR+IN; assessed pain outcomes, recurrence, and complications.

Cohort 30 patients underwent 37 procedures; 89.2% of procedures followed at least one prior ipsilateral TN procedure.

Immediate outcomes 89.2% achieved immediate postoperative pain relief (pain free with or without medication), with no significant differences between procedure groups.

Durability Pain recurred on average at 1.64 ± 1.71 years after the procedure, with no significant differences among groups.

Final follow-up pain freedom At mean 3.14 ± 2.58 years follow-up, 75% of PSR+MVD and 100% of PSR+IN cases were pain free; 52.3% of first PSR cases required additional procedures.

Complications Overall complication rate was 29.7% with no significant differences between groups; ipsilateral facial numbness was common (59.5%) and treated as an expected outcome rather than a complication.

Conclusion PSR functions effectively as a salvage option for MS-related TN, and adding MVD or IN may improve long-term pain relief without increasing complication rates.

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Long-term outcomes of microvascular decompression for trigeminal neuralgia in multiple sclerosis

J Neurosurg 144:1122–1133, 2026

This systematic review and meta-analysis evaluates microvascular decompression (MVD) outcomes for trigeminal neuralgia in patients with multiple sclerosis (TN-MS). The authors pooled 30 studies (265 unique TN-MS patients), finding neurovascular compression in 96.6% and a pooled long-term pain-free (BNI I) success rate of about 30%, with low heterogeneity and primarily transient sensory complications.

The report discusses limited, mostly retrospective evidence, methodological limitations, and potential dual mechanisms of TN in MS. Authors conclude MVD yields lower success than in classic TN but remains a reasonable option for selected TN-MS patients with demonstrable neurovascular compression; they call for prospective studies and refined patient selection.

Objective Evaluate long-term pain relief and complications of microvascular decompression (MVD) for trigeminal neuralgia in patients with multiple sclerosis (TN-MS), a group traditionally considered poor candidates for MVD.

Methods Systematic review/meta-analysis (PRISMA) of PubMed, Embase, Scopus, and Web of Science (search June 2024); primary endpoint was long-term pain-free status BNI I at final follow-up using random-effects meta-analysis of proportions.

Evidence base 30 studies were included, covering 429 TN-MS patients treated with MVD, representing 265 unique patients.

Neurovascular compression Compression was identified in 96.6% of reported TN-MS cases (via MRI and/or intraoperative findings).

Long-term efficacy Pooled long-term pain-free outcome (BNI I) after MVD was 30.2% (95% CI 24.2%–36.9%), with low heterogeneity across analyses.

Complications The most commonly reported complication after MVD was transient facial numbness (with other complications variably reported).

Interpretation MVD is less effective in TN-MS than in classic TN, but can still provide meaningful benefit, particularly when neurovascular compression is present.

Conclusion/implication MVD should not be categorically excluded for TN-MS; further prospective studies are needed to improve selection and outcomes.

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Percutaneous Trigeminal Ganglion Stimulation as a Treatment Modality for Anesthesia Dolorosa

Neurosurgery Practice 2026;7(1):e000191.

This case report describes successful percutaneous trigeminal ganglion stimulation (TGS) in a 71-year-old woman with anesthesia dolorosa (AD) after multiple rhizotomies for trigeminal neuralgia related to multiple sclerosis. The authors detail implantation technique, trial and permanent lead placement, stimulation parameters, and sustained clinical improvement over three years without major complications.

The article situates TGS within neuromodulation strategies for refractory deafferentation pain, reviews prior peripheral nerve stimulation evidence, and discusses mechanisms, patient selection considerations, and hardware anchoring challenges. The authors conclude TGS is a promising option for refractory AD and call for further research to refine indications and device fixation.

Condition Anesthesia dolorosa (AD) is a rare, debilitating deafferentation pain syndrome (incidence ~0.3%–2%) that often follows iatrogenic trigeminal nerve injury such as trigeminal rhizotomy and is frequently refractory to medications.

Patient case A 71-year-old woman with trigeminal neuralgia secondary to multiple sclerosis developed severe, medically refractory AD after multiple rhizotomies, with burning jaw pain and substantial numbness that impaired eating, talking, and oral hygiene.

Intervention An off-label percutaneous trigeminal ganglion stimulation (TGS) externalized trial was offered because some sensation was preserved.

Procedure Under fluoroscopic guidance, an electrode was advanced via a Jamshidi needle through the foramen ovale to the trigeminal ganglion region and secured on the cheek/postauricular area; an external generator was connected for the trial.

Trial outcome Over ~2 weeks of continuous stimulation, pain during episodes improved from 9/10 to 0–1/10, and relief persisted until permanent implantation 2 months later.

Durability After permanent implantation (St. Jude Octrode lead; generator in left chest wall), the patient reported 0–1/10 burning pain with return to baseline activities, with stable relief for 3 years with minimal setting adjustments alongside baclofen and pregabalin.

Rationale TGS is proposed to help restore tonic signaling to the trigeminal nucleus to rebalance excitatory/inhibitory processing and alleviate pain, potentially even with severe peripheral deafferentation.

Implications/limits This single case supports TGS as a promising option for refractory AD and warrants further investigation; practical challenges include achieving robust facial lead anchoring and defining optimal indications/trial criteria.

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Historical evolution of microvascular decompression after Jannetta’s establishment: Anatomical maps and physiological compasses—a narrative review

Acta Neurochirurgica (2026) 168:74

This narrative review chronicles five decades of refinement in microvascular decompression (MVD) for trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia, tracing developments from Jannetta’s microsurgical breakthrough to contemporary practice. It emphasizes evolving microsurgical anatomy, tailored craniotomies, endoscopic/exoscopic visualization, and nuanced decompression techniques such as noncompressive transposition versus prosthetic interposition.

The article also highlights operative support advances—high-resolution MRI/MRA, virtual simulation, and intraoperative neuromonitoring (BAEP, LSR)—as physiological “compasses” that improve safety and outcome durability. Together, anatomical “maps” and physiological feedback frame current standards and ongoing challenges in achieving long-term, biologically harmonious decompression.

Microvascular Decompression (MVD) Evolution: MVD has developed from Jannetta’s original microsurgical demonstration of vascular compression into a safe, durable, and standardized surgical treatment for neurovascular compression syndromes, especially trigeminal neuralgia (TN), hemifacial spasm (HFS), and glossopharyngeal neuralgia (GPN).

Anatomical Foundations: Detailed microsurgical anatomy, including the “Rule of Three” for the cerebellopontine angle (CPA), enables tailored, minimally invasive approaches and underpins the understanding of neurovascular conflicts and surgical route selection.

Tailored Surgical Approaches: Three individualized approaches—lateral supracerebellar-infratentorial for TN, infrafloccular for HFS, and transcondylar fossa for GPN—minimize cerebellar retraction and optimize decompression, improving safety and efficacy.

Decompression Strategies: Techniques have shifted from prosthetic interposition (placing a material between vessel and nerve) to noncompressive transposition (mobilizing and securing the vessel away from the nerve), with evidence supporting better long-term outcomes for transposition.

Visualization and Simulation Advances: The integration of endoscopic/exoscopic systems, neuronavigation, and virtual simulation has enhanced visualization, surgical precision, and education, extending the original ethos of microscopic surgery.

Intraoperative Monitoring: Real-time monitoring using brainstem auditory evoked potentials (BAEPs) and lateral spread response (LSR) on facial EMG helps avoid complications and assess decompression adequacy, significantly reducing postoperative morbidity.

Role of Imaging: High-resolution MRI and MRA now routinely identify neurovascular compression preoperatively, though imaging findings are considered supportive rather than diagnostic due to limited specificity in low-grade conflicts.

Sustained First-Line Role: Despite advances in radiosurgery and pharmacotherapy, MVD remains the first-line surgical option for appropriately selected patients, due to its proven long-term efficacy and safety.

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How I do it: microvascular decompression for vago-glossopharyngeal neuralgia

Acta Neurochirurgica (2026) 168:62

This surgical how-to describes microvascular decompression (MVD) for vago‑glossopharyngeal neuralgia, detailing patient selection, imaging requirements, anesthesia, positioning, and a retrosigmoid infrafloccular approach to expose the IX–X root entry zones. It emphasizes preoperative high-resolution MRI identification of neurovascular conflict—most often PICA or vertebrobasilar compression—and perioperative neurophysiological monitoring.

The technique section outlines stepwise microsurgical maneuvers: arachnoid dissection, vessel mobilization or transposition, cautious Teflon interposition when needed, hemostasis, watertight closure, and targeted postoperative surveillance for dysphagia, hoarseness, CSF leak, and other complications. Practical tips for avoiding complications and key informed‑consent elements are provided.

Vago-Glossopharyngeal Neuralgia (VGN): Rare craniofacial pain syndrome (<1% of facial pain cases), often caused by neurovascular conflict involving the posterior inferior cerebellar artery (PICA) and sometimes the vertebrobasilar artery.

Clinical Features: Characterized by paroxysmal, lancinating pain in the oropharynx, tonsillar fossa, base of tongue, or deep ear canal, typically triggered by swallowing, talking, or coughing.

Diagnosis: High-resolution MRI (T2-weighted CISS/FIESTA/DRIVE, 3D TOF angiography) is mandatory to demonstrate neurovascular conflict and guide surgical planning.

First-line Surgical Treatment: Microvascular decompression (MVD) is the most effective and durable option for drug-refractory VGN, aiming to relieve neurovascular conflict without damaging nerve rootlets.

Surgical Approach: Keyhole retrosigmoid craniectomy with infrafloccular approach exposes the root entry zone of cranial nerves IX and X; careful arachnoid dissection and vessel mobilization or Teflon interposition are performed.

Intraoperative Considerations: Intraoperative neuromonitoring of lower cranial nerves is recommended to minimize risk of postoperative deficits such as dysphagia or hoarseness.

Complications: Main risks include transient dysphagia, hoarseness, or lower cranial nerve palsies, which are usually temporary and resolve within three months.

Outcomes: MVD offers superior and lasting pain relief with functional preservation compared to ablative procedures, making it the preferred surgical option.

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Partial sensory rhizotomy in therapy‑refractory and recurrent trigeminal neuralgia

Acta Neurochirurgica (2026) 168:42

This single-center retrospective analysis reports outcomes of partial sensory rhizotomy (PSR) for therapy-refractory or recurrent trigeminal neuralgia (TN) in 48 patients treated between 2004 and 2023. The study details patient selection, surgical technique, and perioperative findings, noting immediate pain relief in most patients, variable hypesthesia, and acceptable complication rates without permanent deficits.

Long-term follow-up (mean 38 months) found 65% pain-free without medication and 95% overall satisfaction (BNI 1–3), including a substantive subset with multiple sclerosis; recurrence occurred in 27% with some successfully re-operated. The authors conclude PSR is a viable option for selected refractory or recurrent TN patients, emphasizing informed consent about unpredictable sensory deficits

Partial Sensory Rhizotomy (PSR) Role: PSR is a surgical option for therapy-refractory or recurrent trigeminal neuralgia (TN), especially in patients without neurovascular conflict or those who failed previous microvascular decompression (MVD) or other interventions.

Efficacy: PSR provided immediate total pain relief in 87.5% (42/48) of patients; long-term, 72.1% (31/43) had complete or partial pain relief without medication, and 23.3% were satisfied with ongoing medication.

Indications: PSR is particularly relevant for patients with multiple sclerosis (MS)-related TN and those without a clear neurovascular conflict, as well as for those not responding to or preferring to avoid repeated percutaneous or radiosurgical procedures.

Complications: Postoperative hypesthesia is expected and occurred in 77.1% of patients, but was generally well tolerated; no cases of anesthesia dolorosa or corneal anesthesia were observed. Other complications (e.g., CSF fistula, transient hearing impairment) were rare and resolved with treatment.

Recurrence: The observed recurrence rate after PSR was 27.1%, consistent with previously reported rates (10–49% over five years), and repeat PSR was effective in patients with recurrent pain.

Comparison with Other Treatments: While MVD is preferred when neurovascular conflict is present, PSR offers comparable long-term pain relief in selected patients, but with a higher risk of sensory deficits. Combined MVD+PSR does not improve long-term outcomes if no vascular conflict exists.

Patient Satisfaction: Overall, 95% of patients reported meaningful improvement and satisfaction with PSR, despite sensory deficits, when adequately counseled preoperatively.

Recommendation: PSR should be considered and discussed as a viable surgical alternative for therapy-refractory or recurrent TN, particularly in MS patients and those not suitable for or preferring to avoid other invasive procedures.

 

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Microvascular Decompression for Patients With Type 1 Trigeminal Neuralgia Using Vein Sacrifice and a Teflon Transposition Technique: A 23-Year Cohort

Neurosurgery 98:588–596, 2026

This study reports outcomes from a 23-year, prospectively maintained cohort of 523 patients with unilateral Type 1 trigeminal neuralgia treated by microvascular decompression using vein sacrifice and a Teflon transposition technique. Primary outcome was long-term pain-free survival without medications, with median follow-up 8.2 years and 5-, 10-, 15-year pain-free rates of 77.6%, 72.5%, and 69.7%, respectively.

Operative details, complications, and reoperation rates are presented: arterial transposition was performed when possible, veins contacting the nerve were sacrificed, and Teflon pledgets used to maintain separation. Complications were uncommon and generally non-disabling (most frequent: facial numbness, diplopia); true Teflon granulomas were rare but noted in isolated reoperations.

Microvascular decompression (MVD) is the most effective surgical treatment for medically unresponsive Type 1 trigeminal neuralgia (TN), aiming to eliminate neurovascular contact with the trigeminal nerve using arterial transposition, vein sacrifice, and polytetrafluoroethylene (PTFE, “Teflon”) implantation when appropriate.

Study outcomes show that 92.7% of patients were initially pain-free without medications after MVD, with pain-free survival rates of 77.6% at 5 years, 72.5% at 10 years, and 69.7% at 15 years.

Operative technique selection depends on intraoperative findings: arteries are transposed and secured with PTFE whenever possible, veins in contact with the nerve are sacrificed, and partial sensory rhizotomy is reserved for cases without significant vascular compression.

Complication rates are low; the most common was new or worsened facial numbness (7.1%), with higher rates when veins were sacrificed (6.9%) versus arterial decompression alone (1.6%). Venous infarction occurred in 0.6% of patients, and Teflon granuloma in 0.4%.

Pain-free survival was lower in women (hazard ratio 1.48, P = .03), but not associated with pain duration, previous ablative surgery, or new facial numbness.

Vein sacrifice is generally safe and facilitates surgical exposure, though it carries a low but real risk of venous complications; evidence is mixed regarding whether preserving or sacrificing the superior petrosal vein impacts complication rates.

PTFE (“Teflon”) material is widely used for vessel transposition; however, true Teflon granulomas—characterized by mass effect, edema, and inflammatory response—are rare and should not be used to describe all cases of recurrent pain with adherent PTFE.

Terminology precision is important: “Teflon” is a trademark for Chemours’ PTFE products, and not all PTFE felt used in surgery is identical. Variability in material properties may affect surgical outcomes and study reproducibility.

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A Scoping Review of Focused Ultrasound- Blood-Brain Barrier Opening for Treatment of Chronic Pain

Neurosurgery 98:328–338, 2026

This scoping review evaluates focused ultrasound–mediated blood–brain barrier opening (FUS‑BBBO) as a targeted drug‑delivery strategy to treat chronic pain, summarizing systematic literature screening and preclinical evidence. It outlines how FUS parameters, microbubbles, and regional targeting can transiently permit delivery of drugs and particles otherwise excluded by the BBB, potentially improving efficacy and reducing systemic toxicity.

The document surveys candidate therapeutics (opioids, peptides, antibodies, gene therapies) and particle vehicles (nanoparticles, liposomes, niosomes, AAVs), highlights preclinical successes and delivery challenges, and stresses safety, parameter optimization, and the need for human trials. It concludes that FUS‑BBBO combined with advanced delivery platforms holds promise but requires systematic clinical evaluation.

Blood-brain barrier (BBB) challenge: The BBB restricts most drugs from entering the brain, impeding effective pharmacological treatment of chronic pain, with only small, lipophilic molecules (<400–500 Da) able to cross easily, while 98% of small molecules and nearly all large molecules are excluded.

Focused ultrasound (FUS)-mediated BBB opening (FUSBO): FUSBO uses low-intensity ultrasound and microbubbles to temporarily, noninvasively open the BBB, enabling targeted drug delivery to specific brain regions without thermal damage.

Current pain therapies’ limitations: Opioids, gabapentin, cannabinoids, and other agents have limited efficacy and significant systemic side effects due to poor BBB penetration and susceptibility to efflux mechanisms like p-glycoprotein pumps.

Preclinical evidence, lack of human trials: While FUSBO has shown success in animal models for delivering pain therapies directly to the CNS and enhancing efficacy, no human studies have yet assessed FUSBO for chronic pain treatment.

Advancements in drug delivery particles: Nanoparticles, niosomes, polymeric nanoparticles, gold nanoparticles, and liposomes can be engineered to carry drugs across the BBB, improve bioavailability, and reduce toxicity, especially when combined with FUSBO.

Potential for biologics and gene therapy: FUSBO may enable delivery of monoclonal antibodies, single-chain fragment variable antibodies, and adeno-associated virus (AAV) gene therapies to the CNS, overcoming size and immune barriers.

Safety and technical considerations: FUSBO is generally safe in animal and early human studies, but potential risks include microglial activation, microhemorrhage, and neuronal suppression at high intensities; optimal parameters for various drugs and delivery systems remain to be established.

Outlook and clinical promise: FUSBO combined with advanced drug delivery particles could transform chronic pain management by bypassing the BBB, expanding the range of usable therapies, and improving the therapeutic window, but clinical trials are needed to confirm efficacy and safety in humans.

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Electrophysiological monitoring of trigeminal nerve sensory root using sensory-masseter response for microvascular decompression in trigeminal neuralgia

Acta Neurochirurgica (2026) 168:13

This study presents a novel intraoperative electrophysiological technique—the sensory-masseter response (SMR)—for localizing neurovascular compression (NVC) during microvascular decompression (MVD) for trigeminal neuralgia. In 34 patients, SMR was recorded in 82.4% and showed strong spatial correlation with intraoperatively identified NVC, with significantly lower stimulation thresholds at compression sites (median 0.3 mA).

The authors describe methodology, threshold analyses, mechanistic hypotheses linking focal demyelination and sensory-motor anastomoses to SMR, illustrative cases, safety considerations, and limitations. They conclude SMR offers high spatial specificity as a potential real-time adjunct for MVD, but recommend larger studies to validate clinical utility.

Sensory-Masseter Response (SMR) Technique: SMR is a novel intraoperative electrophysiological monitoring method that applies microcurrent stimulation to the intracranial trigeminal sensory root and records compound muscle action potentials (CMAPs) from the masseter muscle to localize neurovascular compression (NVC) during microvascular decompression (MVD) for trigeminal neuralgia (TN).

High Spatial Specificity and Correlation with NVC: SMR was successfully recorded in 82.4% of cases (28/34), with a strong spatial correlation between SMR-positive sites and intraoperatively identified NVC (p < 0.001).

Lower Stimulation Threshold at NVC Sites: The stimulation threshold required to elicit SMR was significantly lower at NVC sites (median 0.3 mA, IQR 0.2–0.4 mA) compared to distal, central, or non-compressed segments, indicating localized neural hyperexcitability likely due to demyelination.

Mechanistic Basis—Sensory-Motor Root Anastomoses: SMR is likely mediated by abnormal anastomotic pathways between the trigeminal sensory and motor roots at the NVC site, enabling direct excitation of the masseter muscle and bypassing the central reflex arc.

Clinical Utility and Limitations: SMR provides real-time functional feedback for intraoperative localization of NVC, but its clinical value and influence on surgical outcomes require further validation in larger, controlled studies.

Potential Pathogenic Insight: The ability to elicit SMR at NVC sites supports the hypothesis that focal demyelination and abnormal sensory-motor conduction contribute to TN pathogenesis and characteristic symptoms like chewing-triggered pain.

Safety Considerations: SMR stimulation can cause transient blood pressure elevation due to sympathetic activation; precautions include deepening anesthesia and monitoring hemodynamics during stimulation.

Study Limitations: The main limitations include small sample size, absence of SMR testing in non-TN or healthy controls, possible technical constraints in nerve exposure, and restriction of recordings to the masseter muscle only.

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Update and Evaluation of a Preoperative Scoring System to Predict Long-Term Outcomes After Microvascular Decompression in Trigeminal Neuralgia

Operative Neurosurgery 29:824–831, 2025

This clinical research article evaluates and compares two preoperative scoring systems predicting long-term pain freedom after microvascular decompression (MVD) for trigeminal neuralgia (TN). Using a retrospective cohort of 410 patients with mean 63-month follow-up, the study tests the Panczykowski score (system A) and proposes a new four-variable Preoperative TN Scoring System (system B) incorporating age, TN type, neurovascular compression, and response to carbamazepine.

Results show both systems reliably stratify likelihood of pain freedom without medication, with higher scores predicting better outcomes; immediate and late complication rates are reported and limitations—including selection bias and evolving diagnostic criteria—are discussed, emphasizing need for broader external validation before widespread adoption.

Scoring Systems for Trigeminal Neuralgia (TN): Two preoperative scoring systems, the Panczykowski Score (A) and a new 4-variable Preoperative Trigeminal Neuralgia Scoring System (B), were evaluated for predicting long-term pain freedom after microvascular decompression (MVD) in TN patients.

Key Predictive Variables: Age over 45 years, classical TN type, positive response to carbamazepine, and presence/severity of neurovascular compression (NVC) significantly predict postoperative pain freedom without medication.

Scoring System A (Panczykowski): Utilizes three variables—TN type (classical/nonclassical), response to carbamazepine, and graded NVC—to assign a score from 1 to 5; higher scores correlate with greater likelihood of long-term pain freedom.

Scoring System B (Updated): Incorporates four variables—age (>45), TN type, response to carbamazepine, and NVC grade (with updated definitions)—assigning one point for each, for a total score of 0 to 4; higher scores predict increased chance of pain freedom.

Predictive Value: Both scoring systems reliably predict long-term pain freedom after MVD, with patients scoring higher on either system significantly more likely to be pain free without medication at long-term follow-up (up to 82% for highest scores).

Complication Rates: Immediate postoperative complication rate was 3.7% and late complication rate was 8.1%, with facial numbness, infection, and hearing loss among the most common complications.

Clinical Application and Limitations: These scoring systems can guide preoperative counseling and surgical candidate selection but may be limited by selection bias, changing TN diagnostic criteria, and potential oversimplification of complex patient profiles; external validation is needed before universal adoption.

Conclusion: Incorporating individual patient factors into preoperative scoring helps identify TN patients most likely to benefit from MVD, but further research and validation in broader populations are necessary for widespread clinical use.

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Factors Affecting Long-Term Pain Control After Gamma Knife Radiosurgery in Secondary Tumor-Related Trigeminal Neuralgia

Neurosurgery 97:1003–1011, 2025

This clinical study evaluates long-term pain outcomes after Gamma Knife radiosurgery (GKRS) for secondary tumor-related trigeminal neuralgia in 156 patients, reporting complete pain relief (BNI 1) in 38.8% and adequate relief (BNI 2–3) in 47.4% over a median 48.5-month follow-up. The cohort—predominantly schwannomas and meningiomas—received tumor-targeted single-session GKRS with a median dose of 12 Gy and facial hypesthesia noted in 8.3%.

Multivariable analysis identified age ≥50 years and decreased or stable tumor volume at follow-up as strong predictors of favorable pain outcomes, while tumor progression and younger age predicted failure. The authors conclude tumor control contributes to pain relief but is not the sole mechanism, and targeting tumor alone achieved similar BNI 1–3 rates as reports that also targeted the nerve.

• Gamma Knife Radiosurgery (GKRS) Efficacy: GKRS provides complete pain relief (BNI 1) in 38.8% and adequate pain relief (BNI 2-3) in 47.4% of patients with secondary tumor-related trigeminal neuralgia, with a median follow-up of about 48.5 months.

• Predictors of Pain Relief: Age ≥50 years (odds ratio: 6.95) and decreased or stable tumor volume at follow-up (odds ratio: 40.38) significantly predict successful pain relief (BNI 1-3) after GKRS.

• Tumor Control and Pain Relief Relationship: While tumor control (stable or reduced volume) strongly correlates with pain relief, pain relief can still occur without significant tumor shrinkage, indicating other contributing mechanisms.

• Most Common Tumor Types: Schwannomas (67.9%) and meningiomas (29.6%) are the most frequent causes of secondary tumor-related trigeminal neuralgia treated with GKRS.

• Complications: Facial hypesthesia is the most common complication post-GKRS, affecting 8.3% of patients; no cases of anesthesia dolorosa or worsening pain were reported.

• Tumor Volume Impact: Larger pre-treatment tumor volume is associated with higher rates of pain relief failure; patients with pain relief failure had a median tumor volume of 5.9 cc versus 3.1–4 cc in those with successful outcomes.

• Prior Procedures: Previous interventions (such as radiofrequency ablation, rhizotomy, or tumor resection) do not significantly affect pain relief outcomes after GKRS.

• Alternative Approaches: Targeting the tumor alone with GKRS is effective; nerve targeting may be reserved for cases where tumor-targeted GKRS fails.

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Outcomes After Repeat-Percutaneous Balloon Compression for Recurrent Trigeminal Facial Pain

Neurosurgery 97:1012–1020, 2025

This clinical case series evaluates the safety and efficacy of repeat percutaneous balloon compression (PBC) for recurrent trigeminal neuralgia in 36 patients treated from 2019–2023, reporting 55 procedures. Outcomes include pain-free duration, BNI pain scores, facial numbness, medication reduction, operative metrics, and complications, with midterm follow-up averaging 33 months.

Key findings indicate repeat PBC yields durable pain relief for most patients (72% sustained complete relief), enables medication reduction in 71%, and incurs low complication rates without observed deafferentation pain; multiple sclerosis patients required more repeats but benefited similarly. The study calls for larger comparative trials to confirm these single-center results.

• Repeat Percutaneous Balloon Compression (PBC) Efficacy: Repeat PBC procedures are effective in managing recurrent trigeminal neuralgia, with 72% of patients maintaining complete pain relief at midterm follow-up (mean: 33 months), and 71% able to permanently decrease or eliminate facial pain medications.

• Safety of Repeat PBC: Repeat PBCs do not increase the risk of complications, regardless of the number of procedures or balloon inflation time, and no patients experienced deafferentation pain in this cohort.

• Complication Profile: Minor transient complications occurred in 10.9% of procedures, with only one major complication (carotid artery puncture); most adverse effects were temporary and non-severe, such as transient numbness, chewing difficulties, or partial corneal anesthesia.

• Pain-Free Interval: The mean pain-free interval after the first PBC was 18 months, with longer intervals observed after subsequent procedures (second: 20 months, third: 41 months in one case), and a decreasing proportion of patients requiring further interventions with each repeat procedure.

• Patient Selection and Outcomes: PBC was performed in patients with predominantly neuralgic facial pain who were not candidates for microvascular decompression; patients with multiple sclerosis (MS) required more repeat procedures but still achieved high rates of pain relief.

• Comparison to Other Techniques: Compared to other percutaneous procedures like radiofrequency thermocoagulation (RFT) and glycerol rhizotomy, repeat PBC appears to have fewer severe complications such as deafferentation pain, dysesthesia, or persistent sensory deficits.

• Balloon Compression Time: Longer balloon inflation times (up to 10 minutes for repeat procedures) did not correlate with increased complications and may contribute to longer pain-free intervals, though no statistical significance was found in this study.

• Clinical Recommendation: Given the likelihood of recurrence after percutaneous procedures, PBC is a safe and effective option for recurrent trigeminal neuralgia, especially for patients unsuitable for more invasive surgery, but larger multi-institutional studies are needed for broader validation.

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An Artificial Intelligence Tool for the Diagnosis of Facial Pain

Neurosurgery 97:993–1002, 2025

This study presents development and validation of an AI-based diagnostic decision support tool that distinguishes temporomandibular disorders (TMDs) from trigeminal neuralgia (TN) using a standardized facial pain questionnaire and targeted orofacial examination. Supervised machine learning models (Random Forest, Logistic Regression, SVM) were trained on data from 101 patients, with the Random Forest achieving the best performance (≈90% accuracy; ROC-AUC ~0.95).

The analysis identifies clinically interpretable predictors—TMJ and masticatory muscle tenderness favor TMD, while brief electric-shock–like pain and prior response to trigeminal surgery favor TN—and evaluates class imbalance effects and limitations for clinical deployment. The work emphasizes the need for external validation, cautious integration into workflows, and balanced training to improve generalizability.

• Differentiation Challenge: Temporomandibular disorders (TMDs) and trigeminal neuralgia (TN) both cause orofacial pain but require very different treatments, making accurate diagnosis crucial; TMDs are far more common and often misdiagnosed as TN, leading to inappropriate management.

• AI Diagnostic Tool: A machine learning (ML) model using questionnaire data and physical examination can reliably distinguish TMD from TN with approximately 90% accuracy, with a Random Forest Classifier showing the best performance (F1 score up to 0.953).

• Key Predictive Features: The most important diagnostic indicators are TMJ tenderness and masticatory muscle tenderness (favoring TMD), and brief, unpredictable, electric shock–like pain episodes (favoring TN).

• Data Collection: Comprehensive data—including both patient-reported symptoms and structured physical examination—significantly improves diagnostic accuracy compared to using only a subset of features.

• Prevalence and Misdiagnosis: TMDs affect 5–12% of the population, while TN is much rarer (0.03–0.3%); the high prevalence of TMD means misdiagnosis as TN is a significant concern, with many patients meeting criteria for TN2 possibly having TMD instead.

• Model Robustness: Training ML models on balanced datasets (even when real-world prevalence is imbalanced) improves accuracy and reduces false positives for the minority class (TN).

• Clinical Utility: The AI tool provides transparent, interpretable results that align with clinical reasoning, supporting clinicians in differentiating between TMD and TN, but external validation in diverse populations is needed before routine clinical adoption.

• Limitations: Further research is required for external validation, integration into workflows, and to address potential algorithmic bias; overreliance on algorithmic output should be avoided in favor of combined clinical expertise.

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Long-term outcomes of peripheral nerve field stimulation in patients with refractory trigeminal neuralgia: a cohort study

J Neurosurg 143:982–986, 2025

Peripheral nerve field stimulation (PNFS) for refractory trigeminal neuralgia showed high long-term treatment failure, especially in females, with frequent complications and revisions. Only half of male patients reported lasting benefit. PNFS should be considered cautiously for this condition.

Peripheral nerve field stimulation (PNFS) was studied for refractory trigeminal neuralgia with a long-term follow-up.

Fifteen patients (6 male, 9 female; median age 70) were included, with a median follow-up of 93 months.

PNFS had a high rate of long-term treatment failure, especially in females.

The median time to treatment failure was 2 years (5.1 years in males, 1.5 years in females; p = 0.003).

Only 3 patients (all male) reported ongoing benefit.

Complications and revision surgeries were common (4 patients, 7 revisions).

No significant differences in outcomes were found between classic and secondary trigeminal neuralgia or by patient age.

PNFS should be considered cautiously due to limited long-term efficacy and frequent complications.

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Outcome comparison between interposition and “contactless” transposition microvascular decompression approaches for trigeminal neuralgia

J Neurosurg 143:970–981, 2025

This study compared interposition and “contactless” transposition (Teflon and pericranial sling) microvascular decompression techniques for trigeminal neuralgia. Both were effective, but sling transposition showed improved midterm pain control and fewer complications. The only significant predictor of pain freedom was MRI evidence of clear nerve compression.

• Microvascular decompression (MVD) is a main surgical treatment for trigeminal neuralgia (TN), traditionally using Teflon interposition between nerve and artery.

• Recurrence of TN pain after MVD is often due to Teflon complications, prompting the development of “contactless” transposition techniques such as Teflon and pericranial sling transpositions.

• This retrospective study compared outcomes of interposition, Teflon transposition, and pericranial sling transposition in 305 TN patients.

• Sling transposition was mainly used for severe compression by the superior cerebellar artery and involved securing the artery to the tentorium with a pericranial graft.

• All techniques had similar short-term pain relief and complication rates, but sling transposition showed significantly higher pain-free rates at 2 years compared to other methods.

• Clear vascular compression on MRI was the only significant predictor of pain freedom in multivariate analysis.

• Sling transposition uses autologous tissue, avoids foreign body reactions, and may provide more durable pain control, but is technically more complex.

• Further long-term studies are needed to confirm the durability of sling transposition for TN pain control.

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Enhanced Recovery After Surgery Protocol for Microvascular Decompression in Trigeminal Neuralgia: A Retrospective Matched Cohort Study

Neurosurgery 97:936–944, 2025

Implementation of an enhanced recovery after surgery (ERAS) protocol for microvascular decompression in trigeminal neuralgia significantly reduced hospital length of stay, improved postoperative pain scores, and decreased transient hearing alterations compared to conventional care, without increasing complications, according to a retrospective matched cohort study.

• Enhanced Recovery After Surgery (ERAS) protocol was implemented for microvascular decompression (MVD) in trigeminal neuralgia (TN) patients and compared to conventional care in a retrospective matched cohort study.

• ERAS protocol included preoperative counseling, scalp block, small incisions, minimal muscle dissection, total intravenous anesthesia without narcotics, early enteral feeding, and early mobilization.

• 130 patients (65 ERAS, 65 non-ERAS) were analyzed after propensity score matching for key demographics and comorbidities.

• ERAS group had significantly shorter hospital length of stay (1.46 vs 2.95 days, P < .001) and lower postoperative verbal pain scores (1.63 vs 2.48, P = .03) than controls.

• ERAS patients experienced fewer transient postoperative subjective hearing alterations (0 vs 6 cases, P = .03).

• No significant difference in postoperative Barrow Neurological Institute (BNI) pain scores or major complications between groups.

• Subgroup analysis showed ERAS patients discharged at 24 hours had even lower pain scores than controls.

• Study limitations include retrospective design, small sample size, and use of subjective pain scores; larger randomized trials are needed.

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Long-term outcomes after microvascular decompression for glossopharyngeal neuralgia

Neurosurg Focus 59(3):E19, 2025

Microvascular decompression (MVD) without neurectomy is effective and safe for glossopharyngeal neuralgia (GPN), with 86% long-term pain freedom and minimal complications. Pain location or radiation did not affect outcomes. Redo MVD is effective for persistent neurovascular compression. High-resolution MRI is useful for preoperative assessment.

• Microvascular decompression (MVD) without neurectomy is effective for glossopharyngeal neuralgia (GPN), including redo procedures.

• In a cohort of 29 patients, 86% were pain free at long-term follow-up (mean 65.3 months); 83% were immediately pain free post-op.

• Complication rates were low: 10% immediate and 11% long-term, with mostly mild symptoms.

• Redo MVD was successful in 3 out of 4 patients with persistent neurovascular compression after prior procedures.

• Pain location or direction of radiation did not affect pain outcomes after MVD.

• Most patients had neurovascular compression (NVC) visible on preoperative MRI, commonly involving the posterior inferior cerebellar artery (PICA).

• MVD is effective even in elderly patients and those with failed prior treatments, provided NVC is present.

• Findings support MVD as a primary treatment for classical GPN, guiding patient selection and management.

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