Christopher S. Ogilvy

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.

Brain arteriovenous malformations (bAVMs) are vascular anomalies characterized by direct arterial to venous shunting without an intervening capillary bed, predisposing patients to intracranial hemorrhage and subsequent neurological morbidity and mortality. Evidence suggests that development and evolution of bAVMs are influenced by ongoing molecular and inflammatory processes. Chronic inflammation within the AVM microenvironment has emerged as a key driver of dysregulated angiogenesis, vascular instability, and hemorrhage risk. The objective of this review is to examine the molecular and cellular mechanisms through which inflammatory pathways contribute to AVM development, rupture, and treatment response. A comprehensive search of the Web of Science database was performed from database inception through September 2024. Following removal of duplicate articles, titles and abstracts were screened and full texts were reviewed for relevance. Experimental, translational, and clinical studies investigating inflammatory signaling pathways, immune cell involvement, molecular biomarkers, and therapeutic implications in AVMs were included. A total of 342 studies were included in the final review. Current evidence demonstrates that inflammatory signaling plays a central role in AVM pathobiology. Pro-inflammatory cytokines including interleukin-1β, interleukin-6, and tumor necrosis factor-α promote endothelial activation, leukocyte recruitment, and abnormal angiogenesis within the AVM nidus. Dysregulation of signaling pathways such as VEGF, TGF-β/BMP, NF-κB, Notch, and KRAS/MAPK-ERK contributes to extracellular matrix degradation, vascular remodeling, and vessel fragility. Infiltration by macrophages and neutrophils further amplifies inflammatory cascades through the release of matrix metalloproteinases and reactive oxygen species, increasing rupture risk. In addition to its pathogenic role, inflammation also contributes to success of AVM obliteration using stereotactic radiosurgery through radiation-induced endothelial injury, immune cell recruitment, and progressive vascular fibrosis. Inflammation is a fundamental component of AVM formation, progression, and therapeutic response. Targeting these pathways, in combination with surgical or radiosurgical interventions, may offer new opportunities for improving AVM management and improving approaches in cerebrovascular neurosurgery.

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.

BACKGROUND AND OBJECTIVES: Aneurysms involving the posterior inferior cerebellar artery (PICA) are rare and anatomically diverse, encompassing both true PICA and vertebral artery (VA)-PICA junctional lesions. Flow diversion (FD) has emerged as a promising treatment, though evidence remains limited to small series and reports. METHODS: Retrospective review of a prospectively maintained database was performed, identifying all PICA aneurysms treated with FD between 2013 and 2025 at a single US institution. Twenty-two patients (24 aneurysms) were identified. A systematic review and individual patient-level pooled-analysis were conducted, identifying 7 eligible studies (77 patients, 80 aneurysms). RESULTS: Ninety-nine patients (104 aneurysms) were treated in 103 procedures. Most aneurysms were proximal lesions (72.1%) and saccular (65.4%), with a median size of 5.7 mm. Complete occlusion was achieved in 73%, with a median follow-up of 12.6 months. A good functional outcome (modified Rankin Scale 0-2) occurred in 90.1%, with low mortality (2.0%) unrelated to device placement. Distal aneurysms demonstrated significantly higher occlusion than proximal lesions (100.0% vs 62.0%, P < .001). FD landing in the PICA was also associated with significantly higher occlusion than VA (100.0% vs 62.5%, P < .001). One distal aneurysm in the cohort was treated with VA landing, which achieved complete occlusion. Twelve complications occurred in 11 procedures (7 ischemic, 5 hemorrhagic). CONCLUSION: This large cohort provides insights into the safety and efficacy of FD for PICA aneurysms. FD seems highly effective for distal aneurysms, whereas in proximal lesions it should be considered more selectively, after weighing alternative treatments, given the comparatively lower rates of angiographic occlusion.

Background: Randomized trials have shown equivocal outcomes between a direct aspiration as first-pass technique (ADAPT) and stent retriever (SR) stroke thrombectomy, yet whether specific patient subgroups benefit differentially from one technique over the other remains unknown. Methods: In this retrospective multicenter cohort study, patients with large vessel occlusion were included, and those who underwent ADAPT versus SR first-pass thrombectomy (either as standalone or combined with aspiration) were compared. The primary outcome was a composite of first-pass effect (FPE, modified Thrombolysis In Cerebral Infarction (mTICI) 2c or better with one attempt) with no symptomatic intracranial hemorrhage (sICH). A causal forest model was used to estimate the conditional average treatment effect (CATE) for each patient, with larger CATEs indicating that ADAPT is expected to be more advantageous. Patients were stratified by CATEs, and outcomes were compared between treatment groups. Results: Among 6700 included patients, ADAPT (n=3695, 55%) was associated with a higher rate of FPE with no sICH (39.9% vs 26.9%; adjusted OR (aOR) 2.07, 95% CI 1.77 to 2.41, P<0.001). The causal forest identified significant treatment effect heterogeneity (interaction P<0.001), where ADAPT was more advantageous in more recent years and among patients with M1 occlusions presenting in earlier time windows. Low-CATE patients showed no statistically significant difference between techniques (aOR 0.91, 95% CI 0.57 to 1.45, P=0.70), while medium- and high-CATE patients demonstrated progressively larger ADAPT advantages (aOR 2.06, 95% CI 1.67 to 2.55, and aOR 2.99, 95% CI 2.24 to 3.98, respectively, both P<0.001). Conclusions: ADAPT may be superior to SR for a majority of patients, particularly in recent years, and among patients with M1 occlusions presenting in earlier time windows.

Flow diverters (FDs) are emerging as a treatment strategy for superior cerebellar artery aneurysms (SCAs) despite the limited data on their efficacy and safety. This study evaluated flow diversion (FD) treatment for proximal SCA aneurysms through a single center analysis, systematic review of the literature, and exploratory computational fluid dynamics (CFDs) simulations. Retrospective review of patients with proximal SCA aneurysms treated with FDs at our neurovascular service between 2013 and 2024. We then conducted a systematic review of the literature using the EMBASE, PubMed, and Web of Science to identify patients with SCA aneurysms treated with FD. Data extracted from these studies included demographics, aneurysm characteristics, treatment, and outcomes. Thereafter, a steady-state CFD simulations using a porous-media representation of the implanted device were performed to qualitatively explore hemodynamic differences when the device distally landed in the ipsilateral versus contralateral posterior cerebral artery relative to the aneurysm. Our literature search identified 13 proximal aneurysms from 6 eligible studies; combined with 5 institutional cases, a total of 18 aneurysms were analyzed. Among these, 16 (88.9%) of the aneurysms were saccular, with a mean size of 6.5 mm (range: 2.2–22) and treated with PED (84.6%) and SILK (15.4%) devices. At a mean of 16.1 months (range: 4–53) angiographic evaluation indicated that 72.2% (13/18) achieved complete or near-complete occlusion, with no long-term neurological deficits. Exploratory CFD analysis suggested greater modeled reductions in aneurysm WSS, kinetic energy, and inflow when stent deployment was simulated ipsilateral to the aneurysm. FD is a reported treatment for proximal SCA aneurysms, and can be technically performed in selected cases. However, further studies with larger cohorts and extended follow-up are needed to evaluate long-term efficacy, functional outcomes, and potential delayed complications.