Month: November 2025

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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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Central thalamic deep brain stimulation for disorders of consciousness: an individual participant data meta-analysis

J Neurosurg 143:1217–1226, 2025

This individual participant data meta-analysis evaluates central thalamic deep brain stimulation (DBS) for chronic disorders of consciousness, pooling 49 patients from seven centers to assess neurological outcomes via the JFK Coma Recovery Scale–Revised. Results show modest mean CRS-R improvement, with age and shorter delay to implantation predicting better gains, but insufficient evidence that DBS alters the natural recovery trajectory.

The report details heterogeneity in targets, stimulation schedules, and methodological limitations—no randomized controls, selection bias, and variable reporting—highlighting the need for matched comparative studies, standardized outcome metrics, and refined targeting (CL vs CM-Pf/DTTm) to determine DBS efficacy and optimize patient selection.

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Multi-institutional recommendations on the use of 7T MRI in deep brain stimulation

J Neurosurg 143:1165–1175, 2025

This multi-institutional review presents consensus recommendations for integrating 7T ultrahigh-field MRI into deep brain stimulation (DBS) workflows, drawing on experience from over 1,000 procedures. It summarizes technical challenges—B1+ heterogeneity, susceptibility and gradient nonlinear distortions—and practical solutions for acquisition, distortion correction, and coregistration to ensure stereotactic accuracy.

The document details optimized sequences and target-specific imaging strategies (STN, GPi, thalamic nuclei, ANT, CM), advanced modalities (DTI/DiMANI, QSM, tractography), and multidisciplinary workflow considerations to improve patient-specific anatomical and connectivity-based DBS targeting and programming.

• 7T MRI Advantages: Ultrahigh-field 7T MRI provides superior spatial resolution, signal-to-noise ratio, and tissue contrast, enabling clearer visualization of deep brain structures critical for deep brain stimulation (DBS) targeting compared to 1.5T and 3T MRI.

• Improved DBS Targeting: 7T MRI enhances direct anatomical and connectivity-based targeting for DBS, supporting more precise, patient-specific electrode placement for Parkinson’s disease, essential tremor, and epilepsy.

• Key Technical Challenges: 7T MRI introduces unique challenges including B1+ transmit field inhomogeneity, increased image distortions (gradient nonlinearity and susceptibility), and chemical shift artifacts, all of which require specialized correction and protocol optimization.

• Distortion Correction and Coregistration: Accurate DBS planning with 7T MRI demands robust correction for gradient and susceptibility distortions, careful coregistration with stereotactic CT, and often manual or nonlinear registration adjustments for optimal anatomical alignment.

• Recommended Imaging Sequences: Specific 7T MRI sequences, such as T2-weighted, FGATIR, MP2RAGE, SWI, QSM, and advanced diffusion imaging (DTI/DiMANI), are recommended for visualizing common DBS targets (STN, GPi, thalamic nuclei), each offering distinct advantages for different structures.

• Connectivity and Tractography: Advanced diffusion MRI at 7T allows submillimetric tractography, enabling functional parcellation of DBS targets (e.g., STN, GPi, DRTT), which can improve patient outcomes by supporting symptom- and network-specific targeting.

• Clinical Impact: Implementation of 7T MRI in over 1000 DBS procedures across multiple centers has demonstrated that, with appropriate workflow and expertise, technical challenges can be managed and targeting accuracy and patient outcomes can be improved.

• Multidisciplinary Collaboration: Effective use of 7T MRI for DBS requires close collaboration between neurosurgeons, MR technicians, physicists, and neuroradiologists to optimize protocols and address the complexity of ultrahigh-field imaging

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Fusion Sequence and Risk Factors for Pseudarthrosis in Multilevel Anterior Cervical Discectomy and Fusion

Neurosurgery 97:1153–1161, 2025

This clinical study evaluates fusion rates, fusion timing, and pseudarthrosis risk factors in 119 patients undergoing 2-level versus 3-level anterior cervical discectomy and fusion (ACDF) with minimum two-year follow-up. Fusion was assessed via angular and linear interspinous motion on dynamic radiographs, with Kaplan-Meier and Cox regression analyses.

Key findings show higher and faster fusion in 2-level ACDF; middle levels fuse earliest while caudal levels have lowest rates. Polyetheretherketone (PEEK) cages and multilevel constructs associate with increased pseudarthrosis risk, highlighting material choice and level-specific biomechanics as critical for surgical planning and future research.

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Indirect cognitive mapping in glioma surgery in patients not eligible for awake craniotomy

Acta Neurochirurgica (2025) 167:289

This article presents a neurosurgical technique for indirectly mapping cognitive subcortical white matter pathways during glioma resection in patients who cannot undergo awake craniotomy. Using preoperative DTI and fMRI to create a 3D functional map, the team employs intraoperative monopolar subcortical motor stimulation as a live landmark to infer and protect nearby cognitive tracts like the arcuate fasciculus and IFOF.

Three illustrative cases demonstrate planning limits based on measured motor stimulation thresholds (approx. 1 mA ≈ 1 mm) and show safe resections with preserved cognitive and motor function. The report discusses indications, limitations versus awake mapping, importance of patient counselling about transient deficits, and integration of neuronavigation, tractography, and intraoperative motor mapping.

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The Far-Lateral Approach and Its Variants

Operative Neurosurgery 29:740–745, 2025

This technical report details the far‑lateral craniotomy and its variants for accessing ventral and ventrolateral craniovertebral pathologies, emphasizing indications, anatomical considerations, and operative steps. It outlines positioning, incision choices, bone work including condylar modifications, dural handling, and strategies to protect the vertebral artery and lower cranial nerves.

The article highlights advantages, limitations, and common pitfalls—such as occipitocervical instability with extensive condylectomy, hypoglossal canal risk, and CSF leak prevention—and supplements the text with high‑quality dissections and a 4K instructional video aimed at trainees and early‑career neurosurgeons.

 

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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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Modic Change Edema in Chronic Low Back Pain Treated With Infliximab or Placebo

Spine 2025;50:1091–1101

This randomized, double-blind clinical trial evaluated whether infliximab reduces Modic type 1 (MC1) edema on STIR MRI and whether baseline edema or ADC values modify its effect on disability and low back pain (LBP). Patients with chronic LBP and MC1 received four infliximab or placebo infusions; MRI and clinical outcomes (ODI, pain) were assessed at five and six months.

Results showed no clinically relevant edema reduction by infliximab in the primary per-protocol analysis, and baseline STIR edema or MC-related ADC did not modify treatment effects or prognosticate ODI or LBP. Sensitivity analyses yielded a modest edema signal in the full analysis set, but overall findings do not support infliximab for chronic LBP with MC1.

• Infliximab: Did not have a clinically relevant effect in reducing Modic change (MC) edema at six months in patients with chronic low back pain and MC type 1 (MC1) compared to placebo.

• Disability and Pain: Infliximab did not improve disability (Oswestry Disability Index) or low back pain intensity at five or nine months follow-up versus placebo.

• Edema as Modifier: Baseline MC edema and apparent diffusion coefficient (ADC) values did not modify the effect of infliximab on disability or low back pain.

• Prognostic Value: Baseline MC edema and ADC values did not predict disability or low back pain outcomes, regardless of treatment group.

• Statistical Findings: The odds ratio for reduced MC edema at six months with infliximab versus placebo was not statistically significant in the per protocol analysis (OR 2.2, 95% CI: 0.8–5.8; P = 0.12), but reached statistical significance in the full analysis set (OR 2.1, 95% CI: 1.02–4.5; P = 0.04), though the clinical benefit was limited.

• Clinical Relevance: Any observed difference in clinical improvement between patients with and without reduced edema was near or below the threshold for clinical relevance (10 ODI points, 1.5–2.0 pain points).

• Reliability: MRI assessment methods for MC and edema (using STIR imaging and ADC) showed good to very good inter-rater reliability.

• Recommendation: These results do not support the use of infliximab as a treatment for chronic low back pain with MC1.

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Tentorial Dural Arteriovenous Fistulas: A Retrospective Cohort Study

Operative Neurosurgery 29:678–685, 2025

This single-center retrospective cohort study analyzes 275 patients with tentorial dural arteriovenous fistulas (TDAVFs) treated between 2001 and 2022, detailing demographic, angiographic, and treatment data across six Lawton-classified subtypes. Results highlight a predominance of middle-aged male patients, high immediate occlusion rates with endovascular techniques, and subtype-specific differences in venous drainage patterns and complication rates.

The manuscript compares treatment modalities and outcomes, noting superior petrosal sinus TDAVFs more often require microsurgery, while Galenic and torcular subtypes showed lower immediate cure rates and higher complications or new fistula formation. Follow-up angiographic and clinical data emphasize favorable functional recovery for most patients despite treatment-related risks.

• Patient Demographics: Tentorial dural arteriovenous fistulas (TDAVFs) predominantly affect middle-aged men, with 85.8% of cases occurring in males and a mean age of 51.1 years.

• Subtype Distribution: The most common TDAVF subtype is superior petrosal sinus (34.9%), followed by tentorial sinus (31.6%), Galenic (15.6%), torcular (7.3%), incisural (5.5%), and straight sinus (5.1%).

• Aggressiveness and Presentation: TDAVFs are less common than other DAVFs but are the most aggressive, frequently presenting with hemorrhage or progressive neurological deficits; more than half of patients present with intracranial hemorrhage or nonhemorrhagic neurological deficits (NHNDs).

• Treatment Approach: Most TDAVFs (83.0%) can be effectively treated with endovascular embolization, but superior petrosal sinus TDAVFs more often require microsurgical intervention (31.6% in this group).

• Immediate Occlusion and Complications: Immediate complete occlusion was achieved in 92.8% of treated cases, with Galenic TDAVFs showing a lower occlusion rate and both Galenic and superior petrosal sinus TDAVFs exhibiting higher complication rates (12.5% overall).

• Outcomes: Favorable clinical outcomes (mRS <3) were achieved in 82.6% of patients, with torcular and tentorial sinus TDAVFs associated with better outcomes compared to other subtypes.

• Recurrence and New Fistulas: Recurrence after complete occlusion was rare (0.9%), but torcular TDAVFs had a higher tendency to develop new fistulas post-treatment (2.6% of cases).

• Key Technical Considerations: Endovascular treatment is preferred when feasible, but surgical approaches are indicated for lesions with unfavorable arterial access or higher risk of complications, particularly in superior petrosal sinus TDAVFs.

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Avoidance of Major Vascular Injury in Transcranial Brain Tumor Surgery Using Real-Time Doppler Navigation

Operative Neurosurgery 29:633–638, 2025

This clinical technical note and case series evaluates real-time Doppler probe navigation during transcranial craniotomy for brain tumor resection, describing technique, operative workflow, and outcomes from 501 operations where the Doppler was used. The authors report a low rate of major vessel injury (<1%) and discuss how Doppler guidance complements neuronavigation and ultrasound as tumor resection progresses and brain shift reduces image accuracy.

The paper details patient selection, surgical approaches, probe specifications and intraoperative use, illustrates three case examples with video, and analyzes stroke and infarction rates attributable to vasospasm or small-vessel injury. Limitations include retrospective design and variable probe penetrance; the authors recommend routine Doppler adjunctive use for tumors encasing or adherent to major arteries.

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Sarcopenia Predicts Early Adjacent Segment Disease Development After Anterior and Oblique Lumbar Interbody Fusion

Operative Neurosurgery 29:667–677, 2025

his clinical study evaluates whether sarcopenia, measured by psoas-to-vertebral body morphometrics on preoperative MRI, predicts early adjacent segment disease (ASD) within three years after anterior or oblique lumbar interbody fusion (ALIF/OLIF). Retrospective analysis of 104 patients found sarcopenia strongly associated with ASD, with sarcopenic patients showing markedly higher ASD rates and greater muscle fat infiltration.

The paper reports that psoas area, P:VBR ratios, and age remained significant predictors on multivariate analysis, while spinopelvic parameters lost significance after adjustment. The authors propose routine preoperative morphometric screening to guide surgical planning, risk counseling, and targeted perioperative optimization for high-risk patients.

• Sarcopenia: Preoperative sarcopenia, defined by reduced psoas muscle area relative to vertebral body area, is a strong independent predictor of early adjacent segment disease (ASD) within 3 years after anterior or oblique lumbar interbody fusion (ALIF/OLIF) ().

• ASD Incidence: 24% of patients developed ASD within 3 years post-ALIF/OLIF; 84.21% of sarcopenic patients developed ASD compared to 10.59% of nonsarcopenic patients.

• Morphometric Assessment: Psoas:vertebral body ratio (P:VBR) at L4 on preoperative MRI provides a simple, objective screening tool for sarcopenia and ASD risk stratification.

• Spinopelvic Parameters: Postoperative pelvic tilt (PT) and pelvic incidence-lumbar lordosis (PI-LL) mismatch were associated with ASD in univariate analysis, but not after multivariate adjustment; sarcopenia remained the strongest predictor.

• Other Risk Factors: Older age, higher preoperative disability (ODI), more instrumented/interbody levels, and prior lumbar surgery also increased ASD risk, while gender, BMI, and comorbidities did not.

• Instrumentation vs. Stand-alone Cages: Patients with stand-alone ALIF/OLIF (no posterior instrumentation) had lower rates of ASD, possibly due to less mechanical stress on adjacent segments.

• Clinical Implications: Identifying sarcopenia preoperatively can inform surgical planning, patient counseling, and may guide targeted pre- and postoperative interventions to improve outcome.

• Future Directions: Further research is needed to determine if interventions like resistance training or dietary modification can reduce ASD risk in sarcopenic patients, and to establish standardized diagnostic criteria for sarcopenia in spine surgery.

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Does the Presence of Preoperative Myelomalacia Impact Outcomes Following ACDF?

Spine 2025;50:1539–1546

This retrospective cohort study examines whether preoperative cervical myelomalacia on MRI influences patient-reported outcomes after anterior cervical discectomy and fusion (ACDF) in 518 adults. Results show similar modified JOA (mJOA) recovery between groups, with myelomalacia not independently predicting worse mJOA up to one year postoperatively.

Secondary findings reveal myelomalacia patients had lower baseline pain/disability and less frequent NDI MCID achievement, but multivariable analysis attributed those differences to baseline scores, smoking, and demographics rather than myelomalacia itself. Multilevel myelomalacia correlated with worse baseline mJOA but did not independently affect long-term improvement.

• Preoperative Myelomalacia: Presence of myelomalacia on MRI before anterior cervical discectomy and fusion (ACDF) in patients with mild-moderate myelopathy does not predict worse postoperative mJOA scores or overall patient-reported outcomes at any time point up to one year after surgery.

• Functional Outcomes: Both patients with and without preoperative myelomalacia achieve similar improvements in functional outcomes (mJOA), with no significant difference in the likelihood of reaching the minimum clinically important difference (MCID) for mJOA.

• Neck Disability Index (NDI): Patients with myelomalacia less commonly achieve MCID for NDI at one year, but this is attributable to less severe baseline symptoms and higher rates of current smoking, not the presence of myelomalacia itself.

• Multilevel Myelomalacia: Patients with two or more levels of myelomalacia have worse preoperative mJOA scores but show greater short-term improvement, resulting in similar one-year outcomes compared to single-level myelomalacia; preoperative severity, not the extent of myelomalacia, predicts improvement.

• Baseline Differences: Patients with myelomalacia tend to have lower baseline pain and disability, possibly due to earlier surgical intervention prompted by MRI findings rather than symptom severity.

• Other Patient-Reported Outcomes: Myelomalacia patients may have better physical component scores (SF-12 PCS) and lower neck pain (VAS neck) at one year, but these differences are small and likely reflect baseline characteristics rather than effects of myelomalacia.

• Prognostic Value: Myelomalacia seen on MRI should not be used as a binary prognostic indicator for surgical outcomes in mild-moderate myelopathy; clinical decision-making should consider baseline function and other patient factors.

• Research Implications: Further studies are needed to clarify the impact of myelomalacia severity, chronicity, and timing on outcomes, especially in patients with more severe myelopathy or more extensive cord signal changes

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Awake surgery for IDH-mutant grade 2 glioma involving the corpus callosum: long-term onco-functional results after callosectomy in 157 consecutive patients

J Neurosurg 143:1280–1289, 2025

This clinical study reports outcomes from 157 consecutive patients with IDH‑mutant grade 2 gliomas infiltrating the corpus callosum who underwent connectome-guided awake surgery with callosectomy. It summarizes surgical technique, extent of resection, complication rates, return-to-work statistics, histology, adjuvant treatments, reoperations, and long-term overall survival.

Comparative analysis contrasts complete (total/supratotal) versus incomplete resections, showing higher extent of resection, greater reoperation potential, and longer median overall survival when callosal tumor was fully removed, while preserved function and a 96.8% return-to-work rate underline favorable onco-functional balance.

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Evaluating longitudinal changes of gait parameters following shunt placement in patients with idiopathic normal pressure hydrocephalus

J Neurosurg 143:1254–1261, 2025

This clinical study evaluates objective, longitudinal gait changes in 212 patients with idiopathic normal pressure hydrocephalus (iNPH) following ventriculoperitoneal shunt (VPS) placement, using serial instrumented motion analysis over a median 12-month follow-up. Short-term analyses show significant improvements in all measured gait metrics within three months, with gait velocity, stride length, and stability ratio demonstrating the largest gains.

Longitudinal modeling with generalized additive mixed-effects models reveals that improvements in velocity, stride length, and single support emerge early and plateau around six months, while cadence changes are minimal until later follow-up. The authors note persistent but incomplete recovery relative to healthy norms, discuss methodological limitations, and call for multicenter prospective studies linking objective gait metrics to patient-reported outcomes.

• Idiopathic Normal Pressure Hydrocephalus (iNPH) Characteristics: iNPH is marked by progressive gait disturbance, cognitive impairment, and urinary incontinence, with gait abnormalities increasing fall risk and often presenting as shuffling, short stride, and instability.

• Ventriculoperitoneal Shunt (VPS) Treatment: VPS placement is the standard of care for iNPH, aiming to improve symptoms by diverting cerebrospinal fluid (CSF) after confirmation of shunt responsiveness via CSF tap test.

• Objective Gait Assessment: Gait parameters—including velocity, cadence, stride length, step width, stability ratio, and support phases—were measured using a pressure-sensitive walkway before and at multiple intervals after VPS placement.

• Short-Term Gait Improvements: Statistically significant improvements in all gait parameters were observed within 3 months post-VPS, with the greatest changes in gait velocity (+27%), stride length (+17.5%), and gait stability ratio (−14.1%).

• Longitudinal Gait Outcomes: Improvements in gait velocity, stride length, and single support phase continued up to 6 months post-surgery, then plateaued and persisted through 24 months, although not reaching normative values seen in healthy controls.

• Majority of Patients Benefit: Over 80% of patients experienced improvement in most gait parameters, with durable benefits maintained through long-term follow-up.

• Limitations: The study’s retrospective, single-center design and specialized gait analysis setup may limit generalizability; potential biases include loss to follow-up and lack of control for comorbidities.

• Clinical Implication: Objective gait analysis validates durable improvement after VPS in iNPH, supporting its use for monitoring surgical outcomes and informing patient care.

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Machine Learning–Based Rupture Risk Prediction for Intracranial Aneurysms: A Systematic Review and Meta-Analysis

Neurosurgery 97:1072–1082, 2025

This systematic review and meta-analysis evaluates machine learning (ML) applications for predicting intracranial aneurysm rupture, comparing 124 ML models across 36 retrospective studies (22,462 patients) with the PHASES score. Results show ML—especially deep learning and SVM—achieves higher AUC and specificity than PHASES, with hemodynamic inputs improving test-set specificity but not external validation.

The authors highlight methodological heterogeneity, risks of bias, and overfitting concerns from retrospective single‑center data, urging prospective, standardized studies and external validation before clinical integration of ML rupture‑risk tools.

Machine Learning (ML) Models: ML techniques, including deep learning (DL), support vector machines (SVM), and regression models, show higher specificity and overall diagnostic accuracy than the traditional PHASES score for predicting intracranial aneurysm rupture risk, with comparable sensitivity.

• Deep Learning Performance: DL models achieved the highest sensitivity (up to 0.87), specificity (up to 0.86), and area under the curve (AUC-ROC up to 0.92) among all ML families, indicating strong discriminative ability in rupture risk prediction.

• PHASES Score Limitations: The PHASES score, though widely used, demonstrates lower specificity (0.51) and modest overall discriminative ability (AUC-ROC 0.66), and does not incorporate important risk factors like aneurysm morphology or family history.

• Hemodynamic Parameters: Incorporating hemodynamic variables (e.g., wall shear stress, flow patterns) into ML models improves specificity and accuracy in test sets, but benefits are less pronounced in external validation, possibly due to sample size and generalizability issues.

• Retrospective Data and Overfitting: All included ML models were trained on retrospective, post-rupture data, raising concerns about overfitting and the applicability of these models to pre-rupture clinical decision-making.

• Generalizability Concerns: ML models often perform less well on external validation data due to biases in patient selection, single-center data, and differences in imaging or clinical protocols, while the PHASES score maintains more consistent performance across settings.

• Need for Prospective Validation: There is a critical need for prospective studies and standardized protocols to confirm the clinical utility and reliability of ML-based rupture risk prediction models before integration into routine practice.

• Clinical Implications: ML approaches, especially DL and SVM, have the potential to enhance individualized risk stratification and reduce overtreatment, but methodological challenges and validation in diverse populations remain essential for safe clinical adoption.

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Afferent and efferent fiber systems of the human amygdala: anatomical, pathophysiological, and clinical significance

J Neurosurg 143:1202–1216, 2025

This paper presents a comprehensive neuroanatomical and radiological analysis of the human amygdala, detailing its nuclei, major afferent and efferent fiber systems, and spatial relationships using white matter fiber dissection and diffusion tensor tractography. The authors synthesize structural descriptions with functional roles in emotion, memory, olfaction, and seizure propagation, emphasizing clinical relevance for neuroclinicians.

The study maps key pathways—the ansa peduncularis, ventral and dorsal amygdalofugal routes, stria terminalis, medial forebrain bundle, olfactory striae, and stria medullaris thalami—correlating anatomy with neurosurgical applications such as deep brain stimulation and lesion resection. Anatomical findings are supported by illustrative dissections, tractography, and a clinical cavernoma case demonstrating surgical implications.

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Comparison of Sagittal Plane Correction With “Bullet” Versus “Banana” Type Transforaminal Lumbar Interbody Fusion Devices

Operative Neurosurgery 29:624–632, 2025

This clinical study evaluates whether “Banana” versus “Bullet” transforaminal lumbar interbody fusion (TLIF) devices produce different immediate postoperative segmental lordosis in one- and two-level degenerative lumbar fusions. Using 241 treated levels from 198 patients, the authors compare radiographic outcomes and perform multivariable regression to identify independent predictors of postoperative segmental lordosis and its change.

Findings show univariable advantages for “Banana” cages in small magnitudes, but multivariable analysis identifies preoperative segmental lordosis, implant-listed lordosis, pelvic incidence, and use of bilateral TLIF windows—not cage morphology—as primary predictors of immediate postoperative segmental correction. The paper recommends further work on subsidence risk and maintenance of correction.

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Five-year follow-up after minimally invasive transforaminal lumbar interbody fusion versus decompression alone for grade 1 spondylolisthesis: are there any differences in outcomes?

J Neurosurg Spine 43:547–556, 2025

This multicenter, prospective registry study compares 60-month outcomes after minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) versus minimally invasive tubular decompression for Meyerding grade 1 degenerative spondylolisthesis. Patient-reported outcomes (ODI, NRS for back/leg pain, EQ-5D, NASS satisfaction) improved significantly in both cohorts, with MIS TLIF showing greater back-pain reduction and higher satisfaction rates.

Durability differs: MIS TLIF had a markedly lower 5-year reoperation rate than MIS decompression (2.8% vs 15.5%), and multivariable analysis found fusion reduced reoperation odds despite similar long-term PROs. Authors conclude both MIS approaches benefit selected patients, but fusion offers superior reoperation durability.

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Brain Bleeding Associated With Cavitation During Focused Ultrasound Ablation

Neurosurgery 97:1215–1218, 2025

This report presents two cases of symptomatic intracranial hemorrhage occurring during MR-guided focused ultrasound (MRgFUS) ablation for movement disorders, associated with persistent cavitation activity despite power reductions. Both patients developed contralateral motor deficits after sonications; one recovered substantially, the other remained significantly disabled, and imaging confirmed hematomas at the targeted sites.

The authors review procedural variables, cavitation mechanisms, mitigation strategies, and institutional experience (~500 cases, 0.4% incidence), recommending a conservative approach—including treatment termination—when uncontrollable cavitation arises, and urging further study of patient- and system-related risk factors to minimize bleeding risk.

• MRgFUS Complication: Symptomatic brain bleeding can occur during magnetic resonance–guided focused ultrasound (MRgFUS) ablation for movement disorders, although it is a rare complication (approximately 0.4% incidence in a center with over 500 cases).

• Cavitation Risk: Persistent cavitation—microbubble formation and collapse during sonication—is strongly associated with the occurrence of brain hemorrhage in MRgFUS procedures, even when standard mitigation steps (such as lowering power) are taken.

• Case Outcomes: In two reported cases, both patients developed contralateral motor weakness and brain hematoma following persistent cavitation during MRgFUS; one patient recovered functional independence, while the other remained severely disabled.

• Technical Mitigation: When cavitation is detected, the recommended strategy is to reduce sonication power and, if needed, increase duration to maintain energy delivery; however, if uncontrollable cavitation persists, treatment termination should be considered.

• Patient Factors: Bleeding can occur even in patients without traditional vascular risk factors, suggesting procedural factors like cavitation may be more critical than patient comorbidities in these cases.

• Incidence and Reporting: Over 20,000 MRgFUS procedures have been performed globally with very few reports of symptomatic brain bleeding, highlighting the importance of continued reporting to refine safety practices.

• Clinical Implication: MRgFUS is an effective and generally safe treatment for movement disorders, but it is not without risk; both clinicians and patients should be aware that severe complications, though rare, are possible.

• Best Practice: A conservative approach is advised if cavitation cannot be controlled during MRgFUS, and further study into both technical and patient-related risk factors for hemorrhage is warranted.

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