Upfront middle meningeal artery embolization for treatment of chronic subdural hematomas in patients with or without midline shift

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.

Middle meningeal artery embolization for the treatment of unilateral large chronic subdural hematoma patients with significant midline shift: A single-center experience

BACKGROUND

The amount of midline shift (MLS) considered safe for middle meningeal artery embolization (MMAE) in patients with chronic subdural hematoma (CSDH) has not been established. Whether MMAE could be used as upfront treatment for unilateral large CSDH patients with significant MLS (>1 cm) has not been reported.

OBJECTIVE

To investigate the efficacy and safety of MMAE in unilateral large CSDH patients with MLS > 1 cm.

METHODS

Eleven carefully selected CSDH patients with mild or moderate symptoms and significant MLS > 1 cm from 1 May 2021 to 31 August 2022 were included in the study. All patients were treated with MMAE using polyvinyl alcohol (PVA) particles. Outcomes were assessed clinically and with interval imaging studies at follow-up.

RESULTS

All 19 MMAs (unilateral embolization in three patients and bilateral embolization in eight patients) were successfully embolized. All 11 patients were followed for subsequent months, and there was no recurrence and enlargement of CSDH. Procedural adverse events, mortality, or complications were not observed. The average time to achieve a 50% reduction in MLS was approximately four weeks, while it took approximately eight weeks to achieve a 50% reduction in maximal volume. All 11 patients showed improvement in their neurological symptoms at three days post-operation, including four hemiplegic patients.

CONCLUSIONS

MMAE may demonstrate safety in carefully selected CSDH patients with significant midline shift (MLS > 1 cm), particularly in those who are not suitable for surgery, thus providing a potential alternative approach.

Analysis of middle meningeal artery embolization for the treatment of chronic, acute on chronic, and subacute subdural hematomas

Background

Chronic subdural hematoma (cSDH) is a common sequela of traumatic brain injury. Middle meningeal artery embolization (MMAE) has shown promising results as an emerging minimally invasive alternative treatment. The purpose of this study is to examine the safety and efficacy of MMAE performed in patients with cSDH, acute-on-chronic, and subacute SDH with a traumatic etiology.

Methods

This retrospective study included cases performed at a Level II Trauma Center between January 2019 and December 2020 for MMAE of cSDHs. Data collected included patient demographic characteristics and comorbidities, SDH characteristics, complications, and efficacy outcomes. The lesion measurements were collected before the procedure, 4-6 weeks and 3-6 months post-procedure.

Results

In our patient population, 78% (39) either had lesions improve or completely resolved. The sample included 50 patients with a mean age of 74 years old. Statistically significant reductions in lesion size were found from pre- to post-procedure in the left lesions, right lesions, and midline shifts. The left lesions decreased from 13.88 ± 5.70 mm to 3.19 ± 4.89 mm at 3-6 months with P < 0.001. The right lesions decreased from 13.74 ± 5.28 mm to 4.93 ± 7.46 mm at 3-6 months with P = 0.02. Midline shifts decreased from 3.78 ± 3.98 mm to 0.48 ± 1.31 mm at 3-6 months with P = 0.02. No complications were experienced for bleeding, hematoma, worsening SDH, pseudoaneurysm, or stroke.

Conclusion

Our pilot study from a single center utilizing MMAE demonstrates that MMAE is successful without increasing treatment-related complications not only for cSDH but also in acute-on-cSDH and SDH with a subacute component.

General Versus Nongeneral Anesthesia for Middle Meningeal Artery Embolization for Chronic Subdural Hematomas: Multicenter Propensity Score Matched Study

BACKGROUND AND OBJECTIVES

The choice of anesthesia type (general anesthesia [GA] vs nongeneral anesthesia [non-GA]) in middle meningeal artery embolization (MMAE) procedures for chronic subdural hematomas (cSDH) differs between institutions and left to care team discretion given lack of standard guidelines. We compare the outcomes of GA vs non-GA in MMAE.

METHODS

Consecutive patients receiving MMAE for cSDH at 14 North American centers (2018-2023) were included. Clinical, cSDH characteristics, and technical/clinical outcomes were compared between the GA/non-GA groups. Using propensity score matching (PSM), patients were matched controlling for age, baseline modified Rankin Scale, concurrent/prior surgery, hematoma thickness/midline shift, and baseline antiplatelet/anticoagulation. The primary end points included surgical rescue and radiographic success rates (≥50% reduction in maximum hematoma thickness with minimum 2 weeks of imaging). Secondary end points included technical feasibility, procedural complications, and functional outcomes.

RESULTS

Seven hundred seventy-eight patients (median age 73 years, 73.2% male patients) underwent 956 MMAE procedures, 667 (70.4%) were non-GA and 280 were GA (29.6%). After running 1:3 PSM algorithm, this resulted in 153 and 296 in the GA and non-GA groups, respectively. There were no baseline/procedural differences between the groups except radial access more significantly used in the non-GA group (P = .001). There was no difference between the groups in procedural technical feasibility, complications rate, length of stay, surgical rescue rates, or favorable functional outcome at the last follow-up. Subsequent 1:1 sensitivity PSM retained the same results. Bilateral MMAE procedures were more performed under non-GA group (75.8% vs 67.2%; P = .01); no differences were noted in clinical/radiographic outcomes between bilateral vs unilateral MMAE, except for longer procedure duration in the bilateral group (median 73 minutes [IQR 48.3-100] vs 54 minutes [39-75]; P < .0001). Another PSM analysis comparing GA vs non-GA in patients undergoing stand-alone MMAE retained similar associations.

CONCLUSION

We found no significant differences in radiological improvement/clinical outcomes between GA and non-GA for MMAE.

Particle embolic agents for embolization of middle meningeal artery in the treatment of chronic subdural hematoma: A systematic review and meta-analysis

OBJECTIVE

In this systematic review and meta-analysis, we investigated the efficacy and safety of middle meningeal artery embolization (MMAE) using particle embolic agents to treat cSDH.

METHODS

To retrieve articles investigating outcomes of patients following MMAE with particle agents and to compare their outcome with conventional treatment, Scopus, PubMed, Embase, and Web of Science were searched using relevant keywords. Original articles with more than 10 cases were included. The meta-analysis was carried out using the R studio and the random-effects model. Publication bias was assessed using Peter's test and quality assessment using NIH tools.

RESULTS

Eleven studies with 359 patients were included. The analysis revealed a pooled recurrence rate of 5% (CI: 3-8%), a need for reoperation rate of 5% (3-9%), and a peri-procedural complication rate of 4% (CI:2-9%) following MMAE with particle embolic agents. The pooled rates of decrease in size or resolution of the hematoma were 85% (CI:66-94%) and 66% (39-86%), respectively. Comparing MMAE using particulate embolysate with conventional treatments, risk ratio (RR) of 0.10 (CI:0.04-0.27) was achieved for recurrence, 0.25(CI:0.13-0.49) for reoperation, and 0.34 (CI:0.16-0.27) for peri-procedural complications. 91% of cSDH cases responded to MMAE with particles in the way they showed either down-sizing or complete resolution of the hematoma on follow-up imaging. In comparison, this rate was found to be 63% following conventional treatment.

CONCLUSION

Middle meningeal artery embolization using particle embolysates is a safe and effective technique for the treatment of cSDH, whether as a standalone intervention or in combination with conventional treatments.

Time and Influencing Factors to Chronic Subdural Hematoma Resolution After Middle Meningeal Artery Embolization

OBJECTIVE

We sought to describe the resolution time of chronic subdural hematoma (CSDH) after middle meningeal artery embolization (MMAE) and potential variables that may affect hematoma resolution.

METHODS

A retrospective analysis was performed on CSDH patients between December 2018 and December 2021. Patient characteristics, radiologic manifestations, and data of hematoma resolution were recorded. Univariate and multivariate analyses were conducted to identify predictors of CSDH resolution time.

RESULTS

A total of 53 patients were enrolled including 53 hematomas. Only 1 participant relapsed and did not require surgical evacuation. Hematoma resolution was observed in 27 (50.9%) at 4 months and 48 (90.6%) cases at the last radiologic follow-up. The median MMAE-to-resolution time was 19 weeks (interquartile range: 8-24). The burr-hole irrigation + MMAE group showed faster hematoma resolution than MMAE alone during early follow-up periods, but no significant difference was found at 6 months. Increased thickness of residual hematoma, excessive postoperative midline shift, high-density hematoma, mixed-density hematoma, separated hematoma, and anticoagulant or antiplatelet agents used were predictive of nonresolution at 4 months as determined by univariate analysis, whereas anticoagulant or antiplatelet agents used and high-density hematoma were not significant on multivariate analysis. No significant association was noted between hematoma resolution and comorbidities or other hematoma radiologic features.

CONCLUSIONS

MMAE is an effective and minimally invasive treatment for CSDH with a lower recurrence rate. The median resolution time of CSDH following MMAE was 19 weeks (interquartile range: 8-24). Burr-hole irrigation contributed to early hematoma resolution but had no significant effect at 6 months. In addition, residual hematoma thickness, postoperative midline shift, and specific type of hematoma were associated with delayed hematoma resolution at 4 months.

Middle meningeal artery embolization for chronic subdural hematoma: a systematic review

Background

Chronic subdural hematoma (cSDH) is one of the most common diseases in neurosurgery. Middle meningeal artery embolization (MMAE) is reportedly an option to prevent recurrence or avoid surgery in patients with cSDH. This study was performed to review the evidence on MMAE for cSDH and evaluate its safety, efficacy, indications, and feasibility.

Methods

We systematically reviewed the literature according to the PRISMA guidelines using an electronic database. The search yielded 43 articles involving 2,783 patients who underwent MMAE.

Results

The hematoma resolution, recurrence, and retreatment rates in the MMAE-alone treatment group (n = 815) were 86.7%, 6.3%, and 9.6%, respectively, whereas those in the prophylactic MMAE with combined surgery group (n = 370) were 95.6%, 4.4%, and 3.4%, respectively. The overall MMAE-related complication rate was 2.3%.

Conclusion

This study shows that MMAE alone is, although not immediate, as effective as evacuation surgery alone in reducing hematoma. The study also shows that combined treatment has a lower recurrence rate than evacuation surgery alone. Because MMAE is a safe procedure, it should be considered for patients with cSDH, especially those with a high risk of recurrence.

Extensive Roles and Technical Advances of Middle Meningeal Artery Embolization for Chronic Subdural Hematoma

Chronic subdural hematoma (CSDH) is a common pathology that typically affects the elderly in Japan, an aging society. Burr-hole irrigation is the standard treatment, but middle meningeal artery (MMA) embolization is a minimally invasive alternative. MMA embolization for CSDH has frequently been reported in recent years, and many technical innovations to improve clinical outcomes have been described. Embolic materials reaching more distally are found to avoid recurrences after MMA embolization. As a result, various studies have described the superiority of embolizing the anterior and posterior branches of the MMA, the advantages of embolic materials reaching beyond the midline, and a high degree of distal penetration using a "sugar rush technique" in which 5% soluble glucose is injected through an intermediate catheter during MMA embolization. Radiographically, reports have described the importance of a "bright falx" sign obtained by infiltrating embolic material beyond the midline and post-embolization enhancement of the dura, capsular membrane, septations, and subdural hematoma fluid as indicators of the spread of embolic materials. This review provides an overview of the current status and future challenges in MMA embolization for CSDH, focusing on technical aspects to improve clinical outcomes.

Middle meningeal artery embolization for treatment of chronic subdural hematomas: does selection of embolized branches affect outcomes?

OBJECTIVE

Middle meningeal artery (MMA) embolization (MMAE) is a new therapeutic modality for chronic subdural hematoma (cSDH). There is limited evidence comparing various MMAE procedural techniques, resulting in significant variations in technique and procedural planning. The objective of this study was to compare outcomes of MMAE by the number and location of MMA branches that were embolized.

METHODS

A single-center retrospective study of patients with cSDH treated by MMAE was conducted. Clinical outcomes, need for re-intervention, and changes in hematoma size were compared between different MMAE techniques.

RESULTS

Ninety-four cSDHs in 78 patients were included. Embolization of the proximal trunk only, distal branches only, or proximal trunk plus distal branches resulted in similar rates of need for rescue surgery (7.4%, 13.0%, and 6.8%, respectively; p = 0.66) and rates of reducing the volume of the hematoma by at least 50% (74.1%, 80.0%, and 77.5%, respectively; p = 0.88). Embolization of only one branch had similar outcomes to embolization of more than one branch, as rescue surgery rates were 9.3% and 7.8% (p = 0.80), and rates ≥ 50% volume reduction were 75.6% and 78.3% (p = 0.76), respectively. Selective embolization of the dominant MMA branch was not associated with significantly different outcomes.

CONCLUSIONS

Outcomes of distal, proximal, or combined proximal and distal MMAE in cSDH are not significantly different. Embolization of more than one branch is not associated with improved treatment efficacy. Arguably, targeting any location in the MMA provides sufficient flow restriction to enable spontaneous hematoma resolution. Accordingly, a technical planning algorithm for cSDH MMAE is suggested.

Short-term follow-up pilot study of sole middle meningeal artery embolization for chronic subdural hematoma: influence of internal architecture on the radiological outcomes

PURPOSE

To identify prognostic factors with emphasis on chronic subdural hematoma (CSDH) architecture that determines short-term outcome of middle meningeal artery embolization (MMAE).

METHODS

Consecutive CSDH patients treated by MMAE (November 2019 and March 2022) were retrospectively analyzed. Four architectures were analyzed: homogeneous, laminar, separated, and trabecular types. Predictor variables from baseline CT were correlated with radiological endpoint (≥ 50% of hematoma volume reduction), time to reach the endpoint, and rate of volume reduction.

RESULTS

Study included 50 patients with 56 CSDHs (median age [first quartile, Q1; third quartile, Q3] 70.5 [60, 78.3] years; 36 were men). Separated type reached the endpoint at a lower rate on both bivariate (p = 0.02) and multivariate Cox model (0.034). Kaplan-Meier curves demonstrated that the median [Q1, Q3] time for 50% of the hematomas to reach the endpoint was 5 [4, 8], 4 [3, 5], 15 [15, 15], and 11 [4, 19] weeks for homogeneous, laminar, separated, and trabecular types, respectively. Linear mixed-effect model demonstrated a significant variation in the slope of hematoma volume reduction that was - 4.16 (95% confidence interval [CI] - 5.4, - 2.9), - 6.7 (95% CI - 8.35, - 5.1), - 2.03 (95% CI - 4.14, 0.08), and - 5.06 (95% CI - 6.8, - 3.32) ml per week for homogeneous, laminar, separated, and trabecular subtypes, respectively.

CONCLUSION

Separated CSDH is a poor prognostic type in achieving radiological endpoint and a slower rate of volume reduction. While, homogeneous and laminar types reached the endpoint faster than separated and trabecular types on short-term follow-up.

Middle Meningeal Artery Embolization for Chronic Subdural Hematoma: Predictors of Clinical and Radiographic Failure from 636 Embolizations

Background Knowledge regarding predictors of clinical and radiographic failures of middle meningeal artery (MMA) embolization (MMAE) treatment for chronic subdural hematoma (CSDH) is limited. Purpose To identify predictors of MMAE treatment failure for CSDH. Materials and Methods In this retrospective study, consecutive patients who underwent MMAE for CSDH from February 2018 to April 2022 at 13 U.S. centers were included. Clinical failure was defined as hematoma reaccumulation and/or neurologic deterioration requiring rescue surgery. Radiographic failure was defined as a maximal hematoma thickness reduction less than 50% at last imaging (minimum 2 weeks of head CT follow-up). Multivariable logistic regression models were constructed to identify independent failure predictors, controlling for age, sex, concurrent surgical evacuation, midline shift, hematoma thickness, and pretreatment baseline antiplatelet and anticoagulation therapy. Results Overall, 530 patients (mean age, 71.9 years ± 12.8 [SD]; 386 men; 106 with bilateral lesions) underwent 636 MMAE procedures. At presentation, the median CSDH thickness was 15 mm and 31.3% (166 of 530) and 21.7% (115 of 530) of patients were receiving antiplatelet and anticoagulation medications, respectively. Clinical failure occurred in 36 of 530 patients (6.8%, over a median follow-up of 4.1 months) and radiographic failure occurred in 26.3% (137 of 522) of procedures. At multivariable analysis, independent predictors of clinical failure were pretreatment anticoagulation therapy (odds ratio [OR], 3.23; P = .007) and an MMA diameter less than 1.5 mm (OR, 2.52; P = .027), while liquid embolic agents were associated with nonfailure (OR, 0.32; P = .011). For radiographic failure, female sex (OR, 0.36; P = .001), concurrent surgical evacuation (OR, 0.43; P = .009), and a longer imaging follow-up time were associated with nonfailure. Conversely, MMA diameter less than 1.5 mm (OR, 1.7; P = .044), midline shift (OR, 1.1; P = .02), and superselective MMA catheterization (without targeting the main MMA trunk) (OR, 2; P = .029) were associated with radiographic failure. Sensitivity analyses retained these associations. Conclusion Multiple independent predictors of failure of MMAE treatment for chronic subdural hematomas were identified, with small diameter (<1.5 mm) being the only factor independently associated with both clinical and radiographic failures. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Chaudhary and Gemmete in this issue.

Middle meningeal artery embolisation: The review of a new treatment for chronic subdural hematomas

Background

This is a literature review aiming to provide an update about the recent findings related to the efficacy of middle meningeal artery embolization (MMAE) in the treatment of chronic subdural hematomas (cSDHs), comparison with conventional therapy and deduction of the current recommendations and indications.

Methods

The literature is reviewed using a search through the PubMed index using keywords. Studies are then screened, skimmed, and thoroughly read. 32 studies fulfilled the inclusion criteria and are included in the study.

Results

Five indications for the application of MMA embolization (MMAE) are deducted from the literature. The usage as a preventive measure after surgical treatment of symptomatic cSDHs in patients with a high risk of recurrence and the usage as a standalone procedure has been the most common reasons for indication of this procedure. Rates of failures for the aforementioned indications have been 6.8% and 3.8%, respectively.

Conclusion

The safety of MMAE as a procedure is regarded as a general theme in the literature and can be considered for future applications. Usage of this procedure in clinical trials with more patient segregation and timeframe assessment relative to surgical intervention are recommendations of this literature review.

Predictors of Subsequent Intervention After Middle Meningeal Artery Embolization for Treatment of Subdural Hematoma: A Nationwide Analysis

BACKGROUND

Middle meningeal artery (MMA) embolization has recently emerged as an effective technique to treat subdural hematomas (SDHs). Studies to date have been limited, largely, to single-center studies with limited follow-up and have not assessed subsequent surgical interventions and factors associated with these interventions.

OBJECTIVE

To evaluate rates of retreatment for SDH after MMA embolization and patient-specific factors that may be important predictors for these interventions.

METHODS

Using an all-payer claims database, Mariner, patients who underwent MMA embolization between January 2010 and October 2020 after the diagnosis of SDH were identified. Rates of post-MMA embolization surgical interventions, including craniotomy and burr hole drainage, were accessed within 5 years following. Patient-specific contributors to the rates of these interventions were studied using Gaussian logistic regression models.

RESULTS

A total of 322 patients were included. Of this cohort, 55 (17.1%) required subsequent intervention within 5 years, with 36 (11.2%) receiving burr hole evacuation and 19 (5.9%) receiving craniotomy. Factor Xa inhibitor use was independently associated with subsequent interventions after MMA embolization procedures (odds ratio: 1.20 [95% CI: 1.02-1.40]). Of the other patient factors evaluated, including age, sex, comorbidity status, and use of vitamin K antagonists, antiplatelets, and factor Xa inhibitors, none were found to be significantly associated with future interventions.

CONCLUSION

Although previous literature has shown MMA embolization to be safe and successful in preventing recurrent SDH, patients undergoing this procedure still carry a risk of future interventions. Patients taking factor Xa inhibitors are at especially high risk of subsequent intervention after MMA embolization.

Cost Comparison for Open Surgery versus Middle Meningeal Artery Embolization in Patients with Chronic Subdural Hematomas: A Propensity Score-Matched Analysis

BACKGROUND

Chronic subdural hematoma (cSDH) can be treated with conventional surgery or middle meningeal artery embolization (MMAE). The cost profiles of open surgery versus MMAE have never been studied. Therefore, we sought to compare the costs of surgical and MMAE treatment of cSDH.

METHODS

Patients treated with open surgery (2006-2019) and MMAE (2018-2020) were identified from the institutional database. Propensity score matching analysis was used to assemble a balanced group of subjects. Detailed hospitalization costs in each group were collected and compared.

RESULTS

A total of 341 conventionally treated and 52 MMAE cases were identified. After propensity score matching, 33 patients were included in each group, for a total of 66 patients for analysis. Direct procedural cost was significantly greater in the MMAE group compared with the open surgery group ($38,255 ± $11,859 vs. $11,206 ± $7888; P < 0.001). Medication cost also was greater in the MMAE group ($6888 ± $6525 vs. $4291 ± $3547; P = 0.048). No significant difference was found in costs for intensive care unit care, pharmacy, therapy, laboratory values, and the emergency department. Imaging costs and other miscellaneous costs (e.g., wound care, preoperative, and postanesthesia care unit) were greater in the open surgery group (P < 0.05). Total hospitalization cost was not significantly different between the 2 groups ($60,598 ± 61,315 vs. $71,569 ± $37,813 for open surgery and MMAE respectively, P = 0.385). No significant differences in number of follow ups or total costs for follow up were found (P > 0.05).

CONCLUSIONS

Open surgery and MMAE offer an overall equivalent cost-profile for cSDH treatment when matching for potential cost confounders. Direct procedural costs are greater in MMAE; however, total hospitalization costs and follow up costs are not significantly different.

Sequential Middle Meningeal Artery Embolization after Burr Hole Surgery for Recurrent Chronic Subdural Hematoma

Middle meningeal artery embolization (MMAE) for chronic subdural hematoma (CSDH) is a novel, minimally invasive treatment. The indications and treatment practices for MMAE are variable and remain controversial. This study aimed to evaluate a strategy involving sequential MMAE after burr hole surgery for treating recurrent CSDH. We performed a retrospective analysis of data from consecutive patients who had undergone MMAE using liquid embolic agents within approximately 2 weeks after burr hole surgery for recurrent CSDH from September 2020 to March 2022. We analyzed patient characteristics, procedural details, CSDH recurrence after MMAE, surgical rescue, and complications. Six of the nine patients who underwent MMAE for CSDH recurrence were male, and the median age was 85 (range, 70-94) years. Five of the nine patients were being administered antithrombotic agents. The median duration between the burr hole surgery and MMAE procedure was 10 (range, 3-25) days. Anterior and posterior convexity branches were targeted for embolization using low-concentration N-butyl cyanoacrylate (NBCA), and the abnormal vascular networks with a cotton wool appearance disappeared after embolization in all cases. The NBCA distribution was observed by high-resolution computed tomography during the procedure; in three of nine cases, the NBCA penetrated not only the MMA but also the inner membrane. No recurrence, surgical rescue, or complications were observed in any patient during the median follow-up period of 3 months. As a minimally invasive treatment for recurrent CSDH, sequential MMAE after burr hole surgery may be a safe and effective option for preventing recurrence.

Middle Meningeal Artery Embolization with Isolated Use of Coils for Treatment of Chronic Subdural Hematomas: A Case Series

BACKGROUND

Middle meningeal artery embolization (MMAE) is a novel approach for treatment of chronic subdural hematoma (cSDH). Studies comparing different procedural techniques for MMAE are lacking. It is unclear whether isolated use of coils results in suboptimal outcomes compared to when particle embolization is also performed. The objectives of this study are to describe the outcomes of coil-only MMAE and compare them with those of combined use of coils and particles.

METHODS

A single-institution retrospective study of cSDH cases treated by MMAE was performed. Clinical outcomes, need for rescue surgery, and changes in hematoma's size were compared between the coil-only and coil + particle groups.

RESULTS

Ninety-four hematomas in 78 patients were included. Twelve cases were treated by a coil-only MMAE procedure, often due to presence of dangerous ophthalmic collaterals. No treatment-related complications were observed in the coil-only group. There was no significant difference between the coil-only and coil + particle groups in baseline hematoma axial thickness, volume, midline shift, and duration of follow-up. The rate of need for rescue surgery was similar between the 2 groups (8.3% vs. 8.5%; P = 0.98). Coiling alone resulted in a similar percentage of reduction in cSDH volume (68.3% vs. 71.8%; P = 0.8) and rate of achieving ≥50% reduction in volume (81.8% vs. 76.3%; P = 0.68) compared to coils + particles.

CONCLUSIONS

Isolated use of coils for endovascular treatment of cSDHs can be as effective as adjunct use of particle embolization. This method eliminates the risks of cranial nerve and visual complications associated with MMAE, can prevent procedural abortion due to presence of dangerous anastomoses, and reduces the technical complexity of the procedure.

Morphological changes in chronic subdural hematomas following upfront middle meningeal artery embolization: sequence, timing, and association with outcomes

OBJECTIVE

Middle meningeal artery embolization (MMAE) is an increasingly utilized approach for the treatment of chronic subdural hematomas (CSDHs). The course of morphological progression of CSDHs following MMAE is poorly understood. Herein, the authors aimed to describe these morphological changes and assess their prognostic significance for the outcomes on follow-up.

METHODS

A single-institution retrospective cohort study of CSDH cases treated by upfront MMAE, without prior or adjunctive surgical evacuation, was performed. Clinical outcomes, complications, and the need for rescue surgery on follow-up were recorded. Hematomas were categorized into 6 morphological subtypes. All baseline and follow-up head CT scans were assessed for CSDH structural appearance, density, and loculation. Changes in CSDH size were quantified via 3D reconstruction for volumetric measurement.

RESULTS

Overall, 52 CSDHs in 45 patients treated with upfront MMAE were identified. Hematomas were followed for a mean of 92.9 days. Volume decreased by ≥ 50% in 79.6% of the CSDHs. The overall rescue surgery rate was 9.6%. A sequence of morphological changes after MMAE was identified. Hematomas that diverged from this sequence (5.4%) all progressed toward treatment failure and required rescue surgery. The CSDHs were categorized into early, intermediate, and late stages based on the baseline morphological appearance. Progression from early to intermediate and then to late stage took 12.7 and 30.0 days, respectively, on average. The volume of early/intermediate- and late-stage hematomas decreased by ≥ 50%, a mean of 78.2 and 47.6 days after MMAE, respectively. Early- and intermediate-stage hematomas showed a trend toward more favorable outcomes compared with late-stage hematomas. The density of homogeneous hypodense hematomas (HSDHs) transiently increased immediately after MMAE (p < 0.001). A marked decrease in density and volume 1 to 3 weeks after MMAE in HSDHs was detected, the lack of which indicated an eventual need for rescue surgery. In HSDHs, a baseline mean density of < 20 HU, and a lower density than baseline by 1 month post-MMAE were predictors of favorable outcomes. The baseline hematoma volume, axial thickness, midline shift, and loculation were not correlated with MMAE outcomes. Loculated, trabecular, and laminar hematomas, which are known to have unfavorable surgical outcomes, had MMAE outcomes similar to those of other "surgical" hematomas.

CONCLUSIONS

The current study was the first to describe the nature, sequence, and timing of morphological changes of CSDHs after MMAE treatment and has identified structural features that can predict treatment outcomes.

The "Bright Falx" Sign-Midline Embolic Penetration Is Associated With Faster Resolution of Chronic Subdural Hematoma After Middle Meningeal Artery Embolization: A Case Series

BACKGROUND

Chronic subdural hematomas (CSDHs) are common in the elderly population and patients taking antiplatelet/anticoagulation medications. Middle meningeal artery (MMA) embolization has become an adjunctive treatment to observation and surgery. Despite many embolization techniques, best practices for optimal CSDH resolution remain unknown.

OBJECTIVE

To report a retrospective case series of MMA embolization for CSDHs regarding rate of hematoma improvement and the significance of distal embolic penetration into the falx.

METHODS

Retrospective chart review was performed on all patients who underwent MMA embolization for CSDHs between January 2017 and June 2021. Patient demographics, clinical presentation, anticoagulant use, and radiographic features were collected. Pre-embolization and postembolization computed tomography scans were analyzed for volumetric changes and assessed for midline penetration of embolic material in the falx.

RESULTS

MMA embolization was performed in 37 patients and 53 hemispheres. Older patients took longer to obtain complete resolution of CSDHs (r = 0.47, P = .03). Patients with larger pre-embolization (r = 0.57, P = .007) and postembolization (r = 0.56, P = .008) CSDH volumes took longer to completely resolve. Patients who had n-butyl cyanoacrylate embolization with midline penetration, as evidenced by the "bright falx" sign, had faster improvement rates than those who did not (5.64 cm3/d vs 1.2 cm3/d, P = .02).

CONCLUSION

Distal penetration of embolic material, particularly n-butyl cyanoacrylate, into the falx may lead to more rapid improvement of CSDH.

Middle meningeal artery embolization for chronic subdural hematomas. A systematic review of the literature focused on indications, technical aspects, and future possible perspectives

Background:

Chronic subdural hematoma (CSDH) is one of the most common neurosurgical diseases that affect elderly and fragile patients and as a consequence, management can be challenging. Surgery represents the standard treatment; however, alternative options are under investigation. Middle meningeal artery (MMA) embolization is considered a minimally invasive treatment although with poor evidence. In this review, we tried to summarize the findings about MMA embolization as a treatment for a CSDH to provide a useful guidance for clinical practice and for future speculative aspects.

Methods:

Literature review on PubMed until March 2021 was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement. We conducted a research on PubMed with a various combinations of the keywords “CSDH” and “middle meningeal artery” and “embolization,” “refractory subdural hematoma,” and then we reviewed the references of the relevant studies as additional source of eligible articles.

Results:

Among the 35 studies eligible for this review, 22 were case series, 11 were case reports, one was a technical note, and 1 was a randomized trial. A total of 746 patients were found in the literature. Failure rate of MMA embolization was between 3.9 and 8.9% of the cases according the indication to treat CSDH (upfront vs. after surgery).

Conclusion:

The global impression deriving from the data available and the literature is that MMA embolization is a safe procedure with very low complications and with a low failure rate, both when associated with surgery or in case of a standalone treatment.

[Middle meningeal artery embolization for chronic subdural haematoma. Case series and literature review]

Middle meningeal artery embolization as primary method for treatment of chronic subdural hematomas became more popular in past decade. There are few large case series (>150 patients) and literature reviews characterizing advantages and drawbacks of endovascular treatment and technical features of surgeries. In this manuscript, the authors report 11 patients with chronic subdural hematoma scheduled for middle meningeal artery embolization and review the literature data on this issue.

Endovascular Treatment of Chronic Subdural Hematomas through Embolization: A Pilot Study with a Non-Adhesive Liquid Embolic Agent of Minimal Viscosity (Squid)

OBJECTIVE

Endovascular embolization using non-adhesive agents (e.g., ethylene vinyl alcohol copolymer with suspended micronized tantalum dissolved in dimethyl sulfoxide; Squid, Balt Extrusion) is an established treatment of brain arteriovenous malformations, dural arteriovenous fistulas, and hypervascular neoplasms. Middle meningeal artery (MMA) embolization is a relatively new concept for treating chronic subdural hematomas (CSDH). This study aimed to evaluate the safety and effectiveness of the use of Squid in the endovascular treatment of CSDH.

METHODS

Embolization was offered to patients with CSDH with minimal or moderate neurological deficits and patients who had previously undergone open surgery to evacuate their CSDH without a significant effect. Distal catheterization of the MMA was followed by embolization of the hematoma capsule with Squid 12 or Squid 18. Safety endpoints were ischemic or hemorrhagic stroke and any other adverse event of the endovascular procedure. Efficacy endpoints were the feasibility of the intended procedure and a ≥ 50% reduction of the maximum depth of the CSDH confirmed by follow-up computed tomography (CT) after >3 months.

RESULTS

Between November 2019 and July 2021, 10 patients (3 female and 7 male, age range 42-89 years) were enrolled. Five patients had bilateral hematomas, and five patients had previously been operated on with no significant effect and recurrent hematoma formation. The attempted embolization was technically possible in all patients. No technical or clinical complication was encountered. During a post-procedural follow-up (median 90 days), 10 patients improved clinically. A complete resolution of the CSDH was observed in 10 patients. The clinical condition of all enrolled patients during the so-far last contact was rated mRS 0 or 1.

CONCLUSION

A distal catheterization of the MMA for the endovascular embolization of CSDH with Squid allowed for the devascularization of the MMA and the dependent vessels of the hematoma capsule. This procedure resulted in a partial or complete resolution of the CSDH. Procedural complications were not encountered.

Middle Meningeal Artery Embolization for Chronic Subdural Hematoma: A National Database Study of 191 Patients in the United States

BACKGROUND

Middle meningeal artery embolization (MMAE) has been used as an effective minimally invasive treatment for chronic subdural hematoma (cSDH). The demographics and clinical outcomes after MMAE treatment for cSDH have not yet been studied using a national database.

METHODS

We queried all MMAE cases up to October 7, 2020, from the TriNetX Analytics Network. We identified patients >18 years old who underwent MMAE for treatment of cSDH. Patient demographics, baseline characteristics, comorbidities, and clinical outcomes were evaluated within 180 days after MMAE. Analyses of 180-day mortality and recurrence were performed after propensity score matching to control for baseline characteristics and comorbidities.

RESULTS

The study included 191 patients (mean age 71.2 ± 13.5 years, 73.3% male, 69.6% White, 13.6% Black/African American, and 16.8% other race). Essential hypertension (71.3%), heart disease (62.8%), type 2 diabetes mellitus (27.2%), nicotine dependence (23.6%), chronic kidney disease (19.4%), and overweight/obesity (19.4%) were among the most prevalent comorbidities. At presentation, 20.4% and 40.3% of patients were on antiplatelet and anticoagulation therapy, respectively. Outcomes within 180-day follow-up were 6.3% (1.0%-5.8% when propensity matched) for mortality (12 patients), 7.3% for craniotomy/craniectomy after MMAE (14 patients), 0.52%-5.2% for burr hole procedures (1-10 patients), and no patients with low vision/blindness.

CONCLUSIONS

MMAE is a safe and effective minimally invasive procedure for treatment of cSDH. This is the first analysis of patients undergoing MMAE for cSDH using a national database.

The Mini-Craniotomy for cSDH Revisited: New Perspectives

Background: Chronic subdural hematomas (cSDH) are increasingly prevalent worldwide with the increased aging population and anticoagulant use. Different surgical, medical, and endovascular treatments have had varying success rates. Primary neurosurgical interventions include burr hole drainage of the cSDH and mini-craniotomies/craniotomies with or without fenestration of the inner membrane. A key assessment of the success or failure of cSDH treatments has been symptomatic recurrence rates which have historically ranged from 5 to 30%. Pre-operative prediction of the inner subdural membrane by CT scan was used to guide our decision to perform mini-craniotomies. Release of the inner membrane facilitates the expansion of the brain and likely improves glymphatic flow.

Methods: Consecutive mini-craniotomies (N = 34) for cSDH evacuation performed by a single neurosurgeon at a quaternary academic medical center/Level I trauma center from July 2018-September 2020 were retrospectively reviewed. Patient characteristics [age, gender, presenting GCS, GOS, initial CTs noting the inner subdural membrane, midline shift (MLS), cSDH width, inner membrane fenestration, cSDH recurrence, post-operative seizures, infections, length of stay] were extracted from the EMR.

Results: Twenty nine patients had mini-craniotomies as primary treatment of the cSDH. Mean age = 68.9 ± 19.7 years (range 22–102), mean pre-operative GCS = 14.5 ± 1.1, mean MLS = 6.75 ± 4.2 mm, and mean maximum thickness of cSDH = 17.7 ± 6.0 mm. Twenty four were unilateral, five bilateral, 34 total craniotomies were performed. Thirty three had inner membrane signs on pre-operative head CTs and an inner subdural membrane was fenestrated in all cases except for the one craniotomy that didn't show these characteristic CT findings. Mean operating time = 79.5 ± 26.0 min. Radiographic and clinical improvement occurred in all patients. Mean improvement in MLS = 3.85 ± 2.69. There were no symptomatic recurrences, re-operations, surgical site infections, or deaths during the 6 months of follow-up. One patient was treated for post-operative seizures with AEDs for 6 months.

Conclusion: Pre-operative CT scans demonstrating inner subdural membranes may guide one to target the treatment to allow release of this tension band. Mini-craniotomy with careful fenestration of the inner membrane is very effective for this. Brain re-expansion and re-establishment of normal brain interstitial flow may be important in long term outcomes with cSDH and may be related to the recent interests in brain glymphatics and dural lymphatics.