Rahim Abo Kasem

BACKGROUND AND OBJECTIVES: Middle meningeal artery embolization (MMAE) is effective for chronic subdural hematoma (SDH), but failure rates vary and risk prediction tools are lacking. This study developed and validated a machine learning (ML) model to predict MMAE treatment failure for SDH. METHODS: We conducted an international, multi-institutional retrospective cohort study of patients who underwent MMAE for SDH between 2019 and 2025. The cohort was split into training and test sets, stratified by treatment failure, with all hematomas from each patient assigned to a single cohort to prevent data leakage. Multiple ML algorithms were evaluated using 5-fold cross-validation, with gradient boosting selected as the final model. The primary outcome was treatment failure, defined as rescue surgical evacuation or persistent/recurrent SDH requiring retreatment. Model performance was assessed using area under the curve-receiver operating characteristic. Patients were stratified into low-risk (15%) groups using a priori clinically defined thresholds. RESULTS: Among 692 treated hematomas in the test cohort, 64 (9.2%) experienced treatment failure. The gradient boosting model achieved an area under the curve-receiver operating characteristic of 0.856 (95% CI, 0.803-0.902) before calibration and 0.832 (95% CI, 0.766-0.889) after isotonic calibration, with excellent calibration (Brier score, 0.053). The most important predictors were age-platelet interaction, platelet-hemoglobin ratio, platelet count, SDH thickness, and age. Observed treatment failure was 1.6% (95% CI, 0.4%-5.7%) in the low-risk group (n = 124; 17.9%), 6.0% (95% CI, 4.3%-8.4%) in the medium-risk group (n = 516; 74.6%), and 59.6% (95% CI, 46.1%-71.8%) in the high-risk group (n = 52; 7.5%) ( P < .001 for trend), a 37.2-fold difference between high- and low-risk groups. CONCLUSION: This ML model stratified MMAE patients into risk groups with a 37.2-fold difference in treatment failure. High-risk patients had 59.6% failure, whereas low-risk patients had 1.6% failure. Risk stratification may improve patient selection and monitoring.

Background Middle meningeal artery embolisation (MMAE) reduces treatment failure in chronic subdural haematoma (cSDH), but it remains unclear whether to add surgery and which patients benefit. We examined whether adding surgery improves functional recovery, accounting for admission status. Methods We conducted a multicentre cohort study of 2075 patients with cSDH treated with MMAE across 33 sites. The primary outcome was excellent functional recovery (modified Rankin Scale (mRS) 0–1) at the last recorded assessment, the timepoint with highest ascertainment (n=1854); a pre-specified 90-day analysis tested whether the timepoint determined the result. The effect modifier was admission functional status (mRS ≥2 vs 0–1), with doubly robust adjustment for measured baseline differences. Results Among 797 patients impaired at admission, excellent recovery occurred in 111/364 (30%) with surgery plus MMAE versus 101/433 (23%) with MMAE alone (adjusted difference 8.2 percentage points; 95% CI 0.8 to 15.5); among 1057 independent patients, it was 3.1 (−3.8 to 9.9). At 90 days, the impaired-group estimate was similar but less precise (7.5; −4.7 to 19.7; n=436), so the finding did not depend on the timepoint. The difference was largest with haematoma volume >80 mL (17.6; 6.6 to 28.6) and was absent for functional independence, freedom from recurrence or reoperation and survival. Surgical complications occurred in 9/195 (4.6%) impaired patients undergoing evacuation. Conclusions Adding surgery was associated with greater excellent functional recovery among admission-impaired but not already independent patients, consistently at 90 days and confined to the excellent-recovery threshold. Randomised validation stratified by admission function is warranted.

Purpose: Middle meningeal artery embolization (MMAE) is increasingly used for chronic subdural hematoma (CSDH), but the relationship between injected liquid-embolic volume and outcomes is unclear. We evaluated dose–outcome associations and searched for a minimum effective dose. Methods: This retrospective multicenter cohort included 313 patients treated with liquid embolic agents at 12 MESH Registry centers from 2016 to 2024. MMAE was performed alone in 172 patients (55.0%) and adjunctively with surgical evacuation in 141 (45.0%). Dose was assessed as total injected volume per patient and normalized to middle meningeal artery diameter, baseline hematoma thickness, and estimated hematoma volume. The primary outcome was a 180-day composite of retreatment, residual or recurrent hematoma > 10 mm, or death. Logistic regression with multiple imputation, restricted cubic splines, and sensitivity analyses evaluated associations and nonlinearity. Results: Median injected volume was 0.60 mL (interquartile range, 0.50–0.90). Center accounted for 44.5% of variation in log volume, whereas hematoma burden accounted for 0.3%. No dose metric was significantly associated with the primary outcome or 90-day recurrence/reoperation. For absolute volume, the odds ratio per interquartile-range increment was 0.80 (95% confidence interval, 0.56–1.16; p = 0.24). No reliable minimum effective dose was identified. Findings remained consistent across sensitivity analyses and treatment indications (interaction p = 0.30). Procedural complications occurred in 6.4% and were not dose-associated. Conclusion: Within the observed range, injected volume alone was not a consistent determinant of outcome and should not be a procedural target after a satisfactory angiographic endpoint. Future studies should evaluate embolic distribution, distal penetration, and vascular territory coverage.

Introduction: Nonacute subdural hematomas (nSDH) are common yet serious extra-axial hemorrhages that result in significant morbidity and mortality. Middle meningeal artery (MMA) embolization (MMAE) is a recent endovascular treatment that involves occlusion of the MMA, inducing hemostasis in and around the hematoma. While many aspects of MMAE have been explored, there is currently limited data on the optimal extent of embolization. Objective: To determine whether single or multiple pedicle embolization of the MMA is superior in inducing hemostasis in nSDH. Methods: We compared single versus multi pedicle embolization by a retrospective multicenter analysis of nSDH patients who underwent MMAE between 2019 and 2024 at participating centers in the MESH (MMA Embolization for Subdural Hematoma) Registry. 679 patients who received a liquid embolic agent with branch-level embolization data were included. Results: While multi-pedicle embolization hastened nSDH thinning at 1 month (5.7 vs. 3.3 mm reduction; difference 2.4 mm, 95% CI 1.0–3.8; P = .002), by 3 months thickness reduction had converged between groups (8.2 vs. 8.4 mm; P = .91). Among 679 patients (456 multi-pedicle, 223 single-pedicle), favorable functional outcome (mRS 0–2) was more frequent with multi-pedicle embolization (53.5% vs. 43.0%; adjusted OR 1.81, 95% CI 1.26–2.60; P = .001), whereas recurrence, rescue surgery, and treatment failure did not differ. Conclusion: Future, multi-center randomized prospective trials are warranted to address confounding variables that limit this observational study. Follow-up beyond 3 months was limited, so durability is unknown.

OBJECTIVE: The aim of this study was to develop and validate a machine learning (ML) algorithm to predict the delayed need for syrinx shunt placement following posterior fossa decompression (PFD) for Chiari malformation type I (CM-I) with concurrent syringomyelia. METHODS: This multicenter retrospective cohort study utilized the TriNetX network to identify patients undergoing index PFD for CM-I and syringomyelia (2010–2020) with at least 2 years of continuous follow-up. The primary outcome was unplanned syringosubarachnoid, syringopleural, or syringoperitoneal shunt placement. Five supervised ML classifiers were trained on 30 preoperative clinical and demographic variables using the Synthetic Minority Over-Sampling Technique to address class imbalance. RESULTS: Of 3112 patients (62.3% female, median age 28.4 years) with a median follow-up of 5.1 years, 271 (8.7%) experienced refractory syringomyelia requiring a shunt. The CatBoost classifier achieved the highest discriminative performance on the independent validation set, yielding an area under the curve of 0.87, accuracy of 83%, sensitivity of 0.78, and specificity of 0.82. Shapley Additive Explanations analysis identified adolescent idiopathic scoliosis, prolonged symptom duration, age > 40 years, and preoperative opioid dependency as the strongest predictors of delayed shunt placement. Notably, partial dependence analysis revealed that every 1-month delay in surgical intervention increased the absolute probability of shunting by approximately 0.8%–1.0%. CONCLUSIONS: The CatBoost ML algorithm accurately predicted the delayed need for syrinx shunting after PFD. The prominent risk associated with concomitant scoliotic deformity and surgical delay provides actionable intelligence, strongly supporting early operative intervention and guiding highly individualized long-term postoperative surveillance.

Background: Middle meningeal artery embolization (MMAE) plus surgical evacuation is increasingly used for chronic subdural hematoma (cSDH), but predictors of length of stay (LOS) and outcomes associated with early discharge remain unclear. Methods: We performed a multicenter MESH Registry study (2019–2024) of patients undergoing MMAE and surgical evacuation for symptomatic cSDH. Short-stay discharge was defined as LOS ≤4 days. Predictors were identified using multivariable logistic regression. The 90-day composite adverse event was defined as cSDH recurrence requiring intervention, reintervention (repeat MMAE or surgical evacuation), or 30-day all-cause readmission. Safety was assessed using adjusted logistic regression, generalized estimating equations (GEE), inverse probability of treatment weighting (IPTW), and multiple imputation by chained equations (MICE). Results: Among 647 patients (mean age 72.6 years; 74.0% male), 156 (24.1%) had short-stay discharge. Median LOS was 8 days (IQR 5–15). Older age (aOR 0.76 per 10 years; 95% CI 0.62–0.93; P = 0.008), higher baseline modified Rankin Scale score (aOR 0.79 per point; 95% CI 0.67–0.94; P = 0.007), and greater midline shift (aOR 0.90 per mm; 95% CI 0.85–0.96; P = 0.001) were independently associated with lower odds of short-stay discharge. C‑statistic was 0.683. The 90-day composite event rate was 17.1% in short-stay versus 23.7% in long-stay patients. Short-stay discharge was not significantly associated with the composite outcome on adjusted analysis (aOR 0.56; 95% CI 0.30–1.07; P = 0.08), GEE (aOR 0.61; 95% CI 0.33–1.12; P = 0.11), or MICE (aOR 0.74; 95% CI 0.44–1.25; P = 0.26). IPTW showed a discordant association (OR 0.47; 95% CI 0.24–0.92; P = 0.03). Conclusions: Older age, worse baseline function, and midline shift were associated with longer hospitalization. Short-stay discharge was not associated with a statistically significant increase in adverse-event rates; however, the study was not powered to establish non-inferiority or safety equivalence, and clinically meaningful differences cannot be excluded.

A subset of primary CNS vasculitis (PCNSV) cases can present with clinical and radiological features that closely resemble brain tumors, creating a significant diagnostic challenge for clinicians. Accurate differentiation between these entities is crucial for timely and appropriate management, as their treatment strategies and prognoses differ substantially. The authors report an illustrative case and summarize the published literature on tumor-mimicking PCNSV to show diagnostic features, treatment, and outcomes. This illustrative case involved a 35-year-old male initially presenting with stroke-like symptoms, whose MRI findings suggested a diffuse left hemispheric lesion concerning for glioma. Despite initial biopsies, the diagnosis remained unclear until a subsequent biopsy revealed PCNSV after a course of chemotherapy and radiation therapy. The review included 63 patients with tumor-mimicking PCNSV, with a mean age of 40 years. Common presentations were focal deficits (62%) and headaches (52%). MRI consistently showed T2/FLAIR-hyperintense lesions with variable enhancement and edema. Lymphocytic vasculitis was the predominant histological finding (76%). Most patients (92%) received high-dose steroids. Granulomatous findings were associated with lower odds of recurrence. Tumor-mimicking PCNSV poses a significant diagnostic challenge. Recognizing its diverse presentations is critical for prompt diagnosis and appropriate clinical management. https://thejns.org/doi/10.3171/CASE26201.

BACKGROUND AND OBJECTIVES: Traumatic cerebral venous sinus injury (tCVSI) is a rare but serious complication of traumatic brain injury. Although similar radiographically to spontaneous cerebral venous sinus thrombosis (CVST), tCVSI treatment approaches have not been fully investigated. We characterized complications, clinical outcomes, and recanalization in tCVSI and evaluated treatment approaches. METHODS: In this retrospective review of patients with radiographically confirmed tCVSI across 3 Level 1 trauma centers from 2018 to 2024, we collected patient characteristics, injury patterns, treatment modalities, complications, clinical outcomes, and recanalization data. Primary outcomes were favorable recovery (extended Glasgow Outcome Scale score ≥5) and 30-day mortality. Multivariate regression identified independent predictors of outcomes and recanalization. RESULTS: Among 11 300 patients screened, 254 (2.2%) had tCVSI. Antiplatelet (AP) and anticoagulation (AC) therapy were used in 32% and 19% of patients, respectively. Hemorrhagic complications occurred in 31% of patients treated with AC and 10% receiving AP. Favorable outcomes were achieved in 73.9% of patients, and 30-day mortality was 12.6%. On multivariate analysis, AP (odds ratio [OR] 6.5, 95% CI 2.1-20.0) and AC (OR 4.7, 95% CI 1.3-17.7) therapies were both associated with better outcomes. AP therapy was independently associated with lower 30-day mortality (OR 0.2, 95% CI 0.06-0.66). At the follow-up, 39.9% of patients had complete recanalization of the involved sinus, 17.5% had partial recanalization, and 42.7% were unchanged. Recanalization status on repeat imaging did not correlate with clinical outcomes. CONCLUSION: This multicenter series demonstrates treatment response in patients after tCVSI and describes differences in natural history compared with spontaneous CVST. Both antithrombotic regimens were associated with favorable outcomes, and AP therapy was independently associated with lower mortality, suggesting a potential role in tCVSI management. Recanalization status at follow-up appeared unrelated to clinical outcomes, supporting the need for unique therapeutic approaches for tCVSI compared with spontaneous CVST, particularly in the acute management period.

Purpose: High-grade gliomas are among the most treatment-resistant cancers, with few therapies improving survival despite hundreds of clinical trials. The biostatistical parameters used to design these trials are critical but uncharacterized in aggregate. Currently, no data-driven benchmarks exist to inform these parameters, including the target effect size. This study therefore aimed to analyze trends in their use across neuro-oncology trials. Methods: We systematically searched PubMed for publications of phase 2 and 3 high-grade glioma or medulloblastoma trials comparing two or more arms with a time-to-event primary endpoint. Key biostatistical parameters were extracted from each study, including trial phase, endpoints, effect size, control arm survival assumptions, Type I error, power, sample size, and accrual time. Results: We analyzed 210 trials published between 1976 and 2025, evaluating 254 primary time-to-event endpoints (overall, OS, or progression-free survival or similar). Survival assumptions and target effect sizes (ie, hazard ratios, HRs) used for trial powering varied substantially. Assumed control arm OS was often lower than observed OS, and the application of type I error rates did not consistently reflect the stated hypothesis directionality. Trials with planned sample sizes below 500 and lower HR targets were less likely to meet accrual goals. Trials generally aimed to complete accrual by 36 months with a median follow up of 24 months. Conclusion: This study provides historical benchmarks for sample size assumptions to support more transparent, data-driven, and context-aware trial design. They may also serve as a resource for feasibility planning, protocol development, and statistical justification in future trials.

Background: Recent trials have furthered uncertainty regarding the endovascular benefit for medium vessel occlusions (MeVO). Stent retrievers (SR) were employed in the first attempt in most interventional arm participants. We sought to compare outcomes in acute MCA M2 occlusions between frontline aspiration and SR, and to delineate procedural and anatomical covariates associated with differential treatment effect. Methods: Retrospective analysis of a multicenter stroke thrombectomy cohort identified cases of MT for M2 occlusions. Unmatched and propensity score-matched (PSM) cohorts were generated comparing frontline aspiration to standalone and combined SR. The primary outcome was functional independence (mRS 0–2) at 90 days. Recanalization, symptomatic intracranial hemorrhage (sICH), mortality, and the effect of M2 laterality, division occlusion and procedure time were assessed. Results: About 1734 patients with M2 occlusions underwent either frontline aspiration (n = 711) or SR/combined (n = 958) thrombectomy between 2013 and 2024. PSM analysis favored aspiration for functional independence (49.9% vs 44.0%, OR 1.27 (1.03–1.57)), complete recanalization (61.2% vs 48.7%, OR 1.66 (1.34–2.05)), complete first pass effect (35.0% vs 27.6%, OR 1.42 (1.13–1.78)), and sICH (3.5% vs 6.2%, OR 0.55 (0.33–0.91)), with no difference in mortality. Frontline aspiration had significantly shorter procedural times (median 28 [IQR 15–49.5] vs 51 [IQR 35–78] minutes; p < 0.001). For every minute increase in procedure time, the probability of functional independence decreased significantly (p < 0.001) less with frontline aspiration (0.35%) compared to SR/combined (1.61%). Conclusion: Frontline aspiration for M2 occlusions resulted in better clinical and angiographic outcomes compared to SRs. Future trials for MeVO with a focus on contact aspiration thrombectomy may succeed where recent trials have failed.