Embolic Agent Choice in Middle Meningeal Artery Embolization as Primary or Adjunct Treatment for Chronic Subdural Hematoma: A Systematic Review and Meta-analysis

Newer treatment paradigm improves outcomes in the most common neurosurgical disease of the elderly: a literature review of middle meningeal artery embolization for chronic subdural hematoma

Chronic subdural hematoma (cSDH) is one of the most prevalent neurosurgical diseases, especially in the elderly. Yet, its incidence is predicted to increase further, paralleling the growth of the geriatric population. While surgical evacuation is technically straightforward, it is associated with significant morbidity and mortality. In fact, 30% of patients are expected to have hematoma recurrence and to need repeat surgical evacuation, and 20% of patients are expected to lose independence and require long-term care. A pathophysiology more complex than originally presumed explains the disappointing results observed for decades. At its core, the formation of microcapillaries and anastomotic channels with the middle meningeal artery (MMA) perpetuates a constant cycle resulting in persistence of hematoma. The rationale behind MMA embolization is simple: to stop cSDH at its source. Over the last few years, this "newer" option has been heavily studied. It has shown tremendous potential in decreasing hematoma recurrence and improving neurological outcomes. Whether combined with surgical evacuation or performed as the only treatment, the scientific evidence to its benefits is unequivocal. Here, we aimed to review cSDH in the elderly and discuss its more recent treatment options with an emphasis on MMA embolization.

Internal hematoma architecture predicts subdural hematoma responsiveness to standalone middle meningeal artery embolization

PURPOSE

Subdural hematoma (SDH) is quickly becoming the most common neurosurgical pathology due to the aging population. Middle meningeal artery embolization (MMAE) has recently emerged as an effective adjunct to surgical SDH evacuation by decreasing recurrence risk. MMAE has also shown promise as a standalone SDH intervention, but clinical and radiographic predictors of successful MMAE remain ill-defined.

METHODS

Retrospective chart review from 2020 to 2023 at a single center identified all MMAE cases performed as primary SDH treatment. Cases were classified by hematoma internal architecture as homogeneous, separated, laminar, or trabecular. SDH maximal thickness was assessed on all follow-up imaging and any recurrences or expansions requiring surgery were denoted as treatment failures.

RESULTS

164 standalone MMAE cases were reviewed. Most cases were in male patients (75.0%) with a mean age of 73.2 years. The overall MMAE treatment failure rate was 6.7% with a 4.9% periprocedural complication rate. The cases with trabecular and laminar collections were slightly larger than those with homogeneous and separated collections (16.2 mm vs. 14.2 mm, p = 0.008*), but other baseline characteristics were similar. The MMAE failure rate was significantly lower in the laminar and trabecular subgroup (1.2%) compared to the homogeneous and separated subgroup (12.4%) (p = 0.005*). Homogeneous and separated internal hematoma architecture was the only predictor of MMAE failure in multivariate analysis (OR 10.5, p = 0.027*) and was also associated with delayed SDH resorption (ANOVA: F = 4.8, p = 0.0025*).

CONCLUSIONS

Standalone MMAE is an effective, safe, and durable treatment for non-acute SDHs, and is especially effective for SDHs with more membranous internal architecture.

Embolic Materials' Comparison in Meningeal Artery Embolization for Chronic Subdural Hematomas: Multicenter Propensity Score-Matched Analysis of 1070 Cases

BACKGROUND AND OBJECTIVES

Multiple preferences exist for embolic materials selection in middle meningeal artery embolization (MMAE) for chronic subdural hematoma with limited comparative literature data. Herein, we compare different embolic materials.

METHODS

Consecutive patients undergoing MMAE for chronic subdural hematoma at 14 North-American centers (2018-2023) were classified into 3 groups: (a) particles, (b) Onyx, (c) n-butyl cyanoacrylate (n-BCA). The end points were unplanned rescue surgery, radiographic success (≥50% reduction in hematoma thickness at last imaging "minimum of 2 weeks"), and major complications. Initial unmatched analysis compared the 3 groups; subsequent propensity score matching (PSM) compared particles vs liquid embolics (groups b and c combined). Additional subgroup PSM analyses compared particles vs Onyx, particles vs n-BCA, and Onyx vs n-BCA. All matched analyses controlled for age, sex, concurrent surgery, previous surgery, hematoma thickness, midline shift, pretreatment antithrombotics, and baseline modified Rankin Scale.

RESULTS

Eight hundred and seventy-two patients (median age 73 years, 72.9% males) underwent 1070 MMAE procedures. Onyx was most used (41.4%), then particles (40.3%) and n-BCA (15.5%). Surgical rescue rates were comparable between particles, Onyx, and n-BCA (9.8% vs 7% vs 11.7%, respectively, P = .14). Similarly, radiographic success (78.8% vs 79.3% vs 77.4%; P = .91) and major complications (2.4% vs 2.3% vs 2.5%; P = .83) were comparable. The PSM comparing particles vs liquid generated 128 matched pairs; general anesthesia and bilateral procedures were significantly higher in particles (37.8% vs 21.3%; P = .004 and 39.8% vs 27.3%; P = .034, respectively). No differences in surgical rescue, radiographic improvement, or major complications were noted (P > .05). Concurrently, PSM comparing particles vs Onyx, particles vs n-BCA, and Onyx vs n-BCA, resulted in 112, 42, and 40 matched pairs, respectively, without differences in surgical rescue, radiographic success, or major complications (P > .05).

CONCLUSION

We found no differences in radiological improvement, surgical rescue, or major complications between embolic materials in MMAE. Current randomized trials are exclusively using liquid embolics, and these data suggest that future trials involving particles are likely to produce similar outcomes.

Validity of the Cost-Effectiveness of Middle Meningeal Artery Embolization Following Hematoma Evacuation for Initial Chronic Subdural Hematoma

BACKGROUND

Despite numerous articles about middle meningeal artery embolization (MMAE) highlighting its efficacy and safety for recurrent chronic subdural hematoma (CSDH), the appropriateness of adjunctive MMAE after hematoma evacuation for initial CSDH remains unclear from a cost-effectiveness perspective.

METHODS

Patients with CSDH were enrolled in this study and were prospectively divided into 2 groups: the "conventional treatment" group, which was treated with hematoma evacuation alone, and the "MMAE" group, which was treated with adjunctive MMAE after hematoma evacuation. The proportion of patients requiring retreatment, length of hospital stay, economic costs, and modified Rankin Score were compared between the 2 groups.

RESULTS

In this study, 53 cases were included, with 30 classified into the conventional treatment group and 23 classified into the MMAE group. In the conventional treatment group, the proportion of patients who required surgical retreatment was higher than that in the MMAE group (16.7% vs. 8.7%). The relative risk was 0.522 (95% confidence interval, 0.111-2.45). Although the addition of MMAE increased the cost per hospitalization by 26%, the increase in cost per patient was limited to 12%, owing to the reduction in patients who relapsed and required a second hospitalization. The increase in cost was not statistically significant. The MMAE group had a significantly higher proportion of patients with favorable outcomes (modified Rankin Score 0-2) (56.7% vs. 87.0%, P = 0.0328).

CONCLUSIONS

By minimizing the increase in hospitalization days and procedure costs, MMAE following hematoma evacuation for initial CSDH could decrease the retreatment rate and balance the total medical costs associated with MMAE.

Early single-center experience with middle meningeal artery embolization using Zoom™ 45 Catheter

BACKGROUND

Middle meningeal artery (MMA) embolization for subdural hematomas (SDH) and dural arteriovenous fistulas (dAVFs) has gained momentum in the neuroendovascular space. However, there is variability in the technique for safe and effective embolization. The aim of this report is to describe the technical feasibility and clinical performance of using Zoom™ 45 catheter for MMA access to facilitate embolization.

METHODS

We analyzed all cases of MMA embolization in which the Zoom™ 45 catheter was used and performed in our institution from February 2021 to March 2023 for SDH and dAVFs.

RESULTS

A total of 32 patients were included. Mean age was 64.0 ± 18.0 years, 75.0% (4/32) were male, and 56.7% (17/30), were black. The technical success was achieved in 93.8% (30/32) of cases, with selective embolization utilizing microcatheter directly into frontal and parietal branches for most patients (96.9%, 31/32). Identification of dangerous collaterals, such as lacrimal and petrous branches, prior to embolization, was achieved in most patients (96.9%, 31/32). Bilateral MMA embolization was done in 50.0% (16/32) of patients. The transradial approach and transfemoral approach were used in 53.1% (17/32) and 46.9% (15/32) of patients, respectively. The most common embolization material was n-butyl cyanoacrylate (84.4%, 27/32). There were no access site complications or complications related to the MMA embolization procedures and used devices.

CONCLUSIONS

The use of Zoom™ 45 Catheter seems to be technically feasible, safe, and effective for facilitating MMA access for embolization in the context of SDH and dAVFs.

ARISE I Consensus Statement on the Management of Chronic Subdural Hematoma

ARISE (Aneurysm/AVM/cSDH Roundtable Discussion With Industry and Stroke Experts) organized a one-and-a-half day meeting and workshop and brought together representatives from academia, industry, and government to discuss the most promising approaches to improve outcomes for patients with chronic subdural hematoma (cSDH). The emerging role of middle meningeal artery embolization in clinical practice and the design of current and potential future trials were the primary focuses of discussion. Existing evidence for imaging, indications, agents, and techniques was reviewed, and areas of priority for study and key questions surrounding the development of new and existing treatments for cSDH were identified. Multiple randomized, controlled trials have met their primary efficacy end points, providing high-level evidence that middle meningeal artery embolization is a potent adjunctive therapy to the standard (surgical and nonsurgical) management of neurologically stable cSDH patients in terms of reducing rates of disease recurrence. Pooled data analyses following the formal conclusion and publication of these trials will form a robust foundation upon which guidelines can be strengthened for cSDH treatment modalities and optimal patient selection, as well as delineate future lines of investigation.

Middle meningeal artery embolization for chronic subdural hematoma: A single-center experience and predictive modeling of outcomes

BACKGROUND

Remarkable interest is rising around middle meningeal artery embolization (MMAE) as an emerging alternative therapy for chronic subdural hematoma (cSDH). The study aims to highlight a large center experience and the variables associated with treatment failure and build experimental machine learning (ML) models for outcome prediction.

MATERIAL AND METHODS

A 2-year experience in MMAE for managing patients with chronic subdural hematoma was analyzed. Descriptive statistical analysis was conducted using imaging and clinical features of the patients and cSDH, which were subsequently used to build predictive models for the procedure outcome. The modeling evaluation metrics were the area under the ROC curve and F1-score.

RESULTS

A total of 100 cSDH of 76 patients who underwent MMAE were included with an average follow-up of 6 months. The intervention had a per procedure success rate of 92%. Thrombocytopenia had a highly significant association with treatment failure. Two patients suffered a complication related to the procedure. The best performing machine learning models in predicting MMAE failure achieved an ROC-AUC of 70%, and an F1-score of 67%, including all patients with or without surgical intervention prior to embolization, and an ROC-AUC of 82% and an F1-score of 69% when only patients who underwent upfront MMAE were included.

CONCLUSION

MMAE is a safe and minimally invasive procedure with great potential in transforming the management of cSDH and reducing the risk of surgical complications in selected patients. An ML approach with larger sample size might help better predict outcomes and highlight important predictors following MMAE in patients with cSDH.

Liquid embolic surface area as a predictor of chronic subdural hematoma resolution in middle meningeal artery embolization

BACKGROUND

Liquid embolic agents (LEAs) such as ethylene vinyl alcohol (EVOH) are utilized for middle meningeal artery embolization (MMAE) for chronic subdural hematomas (cSDH). LEAs may be advantageous for MMAE as they are permanent and can penetrate the microvasculature of the subdural membranes. LEA surface area (SA) can quantify this penetration. The segmentation of LEA SA is not described in the literature and may be of interest in refining MMAE technique.

METHODS

We retrospectively collected computerized tomography (CT) scans from 74 patients (with 95 cSDH) who underwent first-line MMAE with EVOH. Non-contrast head CTs were acquired pre-embolization, immediately post-embolization and at 1-, 3-, and 6 month follow-up. A 3D-Slicer was used to segment hematoma volumes and the liquid embolic cast. We hypothesized that greater LEA SA would be correlated with greater improvements in cSDH volumetric resolution.

RESULTS

There was significant resolution in cSDH volumes over the follow-up period compared to preoperative volume (p<0.0001). The LEA SA was significantly correlated with the rate of cSDH resolution at 3 months (R2=0.08, p=0.03), and 6 months (R2=0.14, p=0.01).

CONCLUSIONS

The correlation of LEA surface area with hematoma resolution at 3-months and 6-months suggests greater LEA penetration may improve radiographic outcomes. This study uniquely provides a quantitative radiological perspective on the effect of LEA penetration on cSDH resolution.

Middle Meningeal Artery Embolization for Subdural Hematoma: An Institutional Cohort and Propensity Score-Matched Comparison with Conventional Management

BACKGROUND

The treatment of non-acute subdural hematoma (NASDH) is challenging due to its high recurrence rates and comorbidities of mostly elderly patients. Middle meningeal artery embolization (MMAE) recently emerged as an alternative to surgery in the treatment of NASDH.

OBJECTIVE

To describe a single center's experience of MMAE with Onyx for NASDH and compare it to a surgically treated historical cohort.

METHODS

We performed a retrospective analysis of patients undergoing MMAE for NASDH from 2019 to 2021. MMAE was performed with ethylene vinyl alcohol copolymer (Onyx). Comparisons were made with a historical cohort from 2010 to 2018 who underwent surgical evacuation only, before and after propensity score matching. Outcomes were assessed clinically and radiographically.

RESULTS

We included 44 consecutive patients (55 MMAEs) who underwent MMAE, with a median follow-up of 63.5 days. Twenty-four NASDHs underwent upfront embolization, 17 adjunctive, and 14 for recurrence after prior surgical evacuation, with no significant differences in hematoma and mRS reduction between them. Two patients died during hospitalization and 2 during follow-up, unrelated to the procedure. Mean SDH thickness decreased by 48.3% ± 38.1% (P < 0.001) on last follow-up, which did not correlate with the amount of Onyx injected. Six (13.6%) patients required surgical rescue after embolization. There were no procedure-related complications. The mean modified Rankin Scale (mRS) on admission was 2.8 ± 1.5, which decreased significantly to 1 [1,4] at the last follow-up (P = 0.033). The MMAE (41 hematomas; upfront and adjunctive embolization) and Surgical Evacuation-only (461 hematomas) cohorts were balanced with propensity score mathing. Matching was successful for 41 MMAE and 41 surgical-only hematoma pairs, and only hypertension remained significantly different between the two groups, but there was no significant difference in any outcome.

CONCLUSION

MMAE for NASDH seems safe and effective in appropriately selected patients, non-inferior to surgery, and may become a minimally-invasive alternative. Given our encouraging results, large-scale clinical randomized trials are warranted.

Lidocaine for headache prevention during chronic subdural hematoma embolization

BACKGROUND

Middle meningeal artery embolization (MMAE) for the management of chronic subdural hematomas (CSDH) with ethylene vinyl alcohol (EVOH) causes an evident patient discomfort due to meningeal nociceptors stimulation. The aim of this study was to assess safety and efficacy of intra-arterial lidocaine (IAL) before MMAE of CSDH with EVOH.

METHODS

We analyzed all consecutive patients with bilateral CSDH undergoing MMAE with EVOH. We used a monolateral IAL injection, with casual allocation. We assessed the headache felt by patients during embolization with the visual analog scale (VAS) and compared scores obtained after embolization of both sides. We followed the STROBE guidelines for case-control studies. Paired t-test and χ2 test were used to compare the distribution of variables in IAL vs control group.

RESULTS

Between September 2021 and March 2023, 32 patients underwent bilateral MMAE with EVOH for a CSDH. Lidocaine treatment resulted in a substantially lower VAS score compared to the control group (median 3 vs 7, p < 0.001), with no substantial side effect. Compliance also benefited from lidocaine administration.

CONCLUSIONS

In patients with CSDH undergoing MMAE, IAL seems to reduce pain sensation associated with EVOH injection and to increase patients' compliance during treatment.

Liquid embolic agents for middle meningeal artery embolization in chronic subdural hematoma: Institutional experience with systematic review and meta-analysis

INTRODUCTION

Chronic subdural hematoma (CSDH) is associated with high recurrence rates. Middle meningeal artery embolization (MMAE) has emerged as a promising treatment option. In this systematic review and meta-analysis, we aimed to assess the safety and efficacy of MMAE for CSDH using liquid embolic agents and compare them with particles.

METHODS

We systematically reviewed all studies describing MMAE for CSDH with liquid embolic agents, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Additionally, we included a cohort of patients from our institution using liquid and particle embolic agents. Data were analyzed using random-effects proportions and comparisons meta-analysis, and statistical heterogeneity was assessed.

RESULTS

A total of 18 studies with 507 cases of MMAE with liquid embolic agents (including our institutional experience) were included in the analysis. The success rate was 99% (95% confidence interval [CI]: 98-⁠100%), all complications rate was 1% (95% CI: 0-⁠5%), major complications rate was 0% (95% CI: 0-⁠0%), and mortality rate was 1% (95% CI: 0-⁠6%). The rate of hematoma size reduction was 97% (95% CI: 73-⁠100%), complete resolution 64% (95% CI: 33-⁠87%), radiographic recurrence 3% (95% CI: 1-⁠7%), and reoperation 3% (95% CI: 1-⁠7%). No significant differences in outcomes were found between liquid and particle embolic agents. Sensitivity analyses revealed that liquid embolic agents were associated with lower reoperation rates in upfront MMAE (risk ratio 0.13, 95% CI: 0.02-⁠0.95).

CONCLUSION

MMAE with liquid embolic agents is safe and effective for the treatment of CSDH. Outcomes are comparable to particles, but liquids were associated with a decreased risk of reoperation in upfront MMAE. However, further studies are needed to support our findings.