The Middle Meningeal Artery: Branches, Dangerous Anastomoses, and Implications in Neurosurgery and Neuroendovascular Surgery

Absence of Foramen Spinosum on Computed Tomography Scan Determines Feasibility of Middle Meningeal Artery Embolization

BACKGROUND AND OBJECTIVES

Middle meningeal artery embolization (MMAE) has emerged as a novel treatment of chronic subdural hematoma. In 0.5% of patients, however, there exists an ophthalmic origin of the middle meningeal artery (MMA) known as the recurrent meningeal artery. It is known that the recurrent MMA is associated with failure of its skeletal aperture, the foramen spinosum, to form during development. The aim of this study was to investigate MMAE feasibility as a function of the presence/absence of the foramen spinosum on preprocedure computed tomography (CT) scan.

METHODS

We performed a retrospective review of 100 consecutive patients undergoing MMAE from January 2022 to December 2023 at the Medical University of South Carolina. Preprocedure CT scan of the head was reviewed, and the presence or absence of the foramen spinosum, along with laterality, was recorded. Subsequently, angiographic studies were reviewed.

RESULTS

All patients (n = 100) had preprocedural CT scan available for review. The incidence of an absent foramen spinosum was 3% (n = 3). All absent foramen spinosum were left sided (2F, 1M). All embolization attempts in these patients were aborted due to recurrent meningeal artery. 97% of patients had patent bilateral foramen spinosum (n = 97). Two of these patients possessed partial ophthalmic contribution to the MMA (2%), and embolization was not performed. In patients with patent foramen spinosum, successful embolization was achieved in 92/97 patients (94.8%).

CONCLUSION

The review of preprocedure CT scan may serve as an opportunity to identify patients with ophthalmic arterial origin of the MMA, subverting unnecessary risks associated with catheter angiography.

Use of Spinosum Roentgen Index (S.R.I.) to determine candidacy for middle meningeal artery embolization

INTRODUCTION

Middle meningeal artery embolization (MMAe) is a minimally-invasive approach for the treatment of subdural hematomas (SDH). Small vessel caliber and ectopic origin of the middle meningeal artery (MMA) may lead to unsuccessful embolization and/or serious morbidity. Thus, use of an objective scale to pre-procedurally assess candidacy for MMA embolization is an essential component of operative planning.

METHODS

A retrospective analysis of all patients having undergone MMAe across 4 years at a single institution was performed.

RESULTS

169 MMAe procedures were performed for SDH, of which 3 were found to have a foramen spinosum diameter, termed the "Spinosum Roentgen Index" (SRI), measuring <2 mm on pre-procedure non-contrast CT Head. A statistically-significant correlation was found between foramen spinosum diameter <2 mm and unsuccessful embolization.

CONCLUSION

Assessment of foramen spinosum diameter (Spinosum Roentgen Index (SRI)) may increase suspicion for aberrant MMA anatomy when measuring <2 mm, which can serve as valuable data in assessing risk versus benefit of MMA embolization, and ultimately minimize unexpected intraprocedural or immediate postprocedural complications.

Pitfalls of Preoperative Embolization for Meningiomas: A Case Report on Occult Anastomosis Between the Middle and Posterior Meningeal Arteries

Preoperative embolization facilitates meningioma resection by reducing intraoperative bleeding. The middle meningeal artery (MMA) is frequently targeted; however, the presence of occult anastomoses between the MMA and the posterior meningeal artery (PMA) and their potential involvement in ischemic complications remain poorly understood. A 61-year-old woman with no prior medical history was incidentally found to have a right parietal extra-axial tumor on magnetic resonance imaging (MRI). She was neurologically intact upon admission, but perifocal cerebral edema was observed surrounding the tumor, which measured approximately 33 mm × 27 mm × 22 mm. Given the patient's condition and life expectancy, tumor resection was planned, preceded by preoperative embolization to minimize intraoperative bleeding. Angiography identified the parieto-occipital branch of the right MMA as the primary feeder, and superselective angiography showed no evidence of anastomoses. Microparticles were injected into the MMA; however, immediately afterward, the patient became comatose and exhibited transient dysarthria. Postembolization angiography revealed retrograde visualization of the vertebrobasilar system through previously undetected MMA-PMA anastomoses. Subsequent MRI confirmed extensive ischemic lesions in the posterior lobes, hippocampus, cerebellum, and thalamus. The patient later developed right hemiparesis, clumsiness, dysarthria, and memory impairment, necessitating rehabilitation. While motor symptoms resolved within 10 days, memory disturbance persisted but improved with therapy. This case highlights the risk of ischemic complications due to occult MMA-PMA anastomoses, which may become functionally significant only during embolization, even if undetectable on preprocedural superselective angiography. This dynamic vascular response underscores the need for heightened vigilance in preoperative embolization planning. Clinicians should consider the possibility of latent anastomoses emerging intraoperatively, necessitating careful embolic agent selection and procedural modifications to minimize complications. Recognizing this risk may enhance patient safety and optimize embolization strategies for meningioma treatment.

Quest for the optimal venous access in a complex skull base dural fistula: Case illustrations and principles

Treatment of dural arteriovenous fistulae (DAVFs) is dynamic and evolves between diagnostic and therapeutic angiography.A 79-year-old man with a left jugular foramen DAVF presented with new onset cranial nerve XII palsy. The DAVF progressed from Cognard grade I to IIa + b. A transvenous approach was chosen. Attempts to access the left inferior petrosal sinus (IPS) via the left internal jugular vein failed due to occlusion. An alternative route through the left superior ophthalmic vein and left cavernous sinus to the IPS was devised. Successful coil occlusion of the IPS was achieved. Postoperatively, symptoms resolved, and angiography showed no cortical venous reflux.

Onyx dilution reduces time to resolution of chronic subdural hematomas after middle meningeal artery embolization

BACKGROUND

The benefit of distal embolite penetration for middle meningeal artery (MMA) embolization in chronic subdural hematomas (cSDH) remains controversial.

OBJECTIVE

To compare the use of diluted Onyx with undiluted Onyx in the management of cSDH.

METHODS

This is a retrospective study of patients with cSDH who underwent MMA embolization using Onyx 18 at our institution. The study population was divided into two subgroups based on whether the Onyx used was diluted or not. Baseline characteristics and technical aspects were compared. Primary outcome was cSDH resolution at follow-up. Secondary outcomes included time to resolution and duration of procedure. Univariate statistical analysis was performed.

RESULTS

Of the 111 MMA embolizations performed at our institution, 99 were performed using Onyx 18 only. Within this cohort, 53 (53.5%) cases used standard Onyx and 46 (46.5%) cases used diluted Onyx. The diluted Onyx group had significantly greater volume of embolic agent used measured radiographically (P<0.001). There was no significant difference in duration of procedure. The percentage of cSDH resolution at last follow-up was similar between the two groups (P=0.98), but the time to resolution was significantly shorter in the diluted Onyx group (P=0.02).

CONCLUSION

The use of diluted Onyx for MMA embolization is associated with greater embolization volume achieved under similar procedural times. While the percentage of patients who achieved cSDH resolution with diluted Onyx is similar to that for standard Onyx, the time to cSDH resolution is significantly shorter. Adoption of Onyx dilution can be considered in MMA embolization for cSDH.

Nonopacification of Frontal and Parietal Branches After Middle Meningeal Artery Embolization: A Radiographic Benchmark

BACKGROUND

Middle meningeal artery embolization (MMAE) has revolutionized the armamentarium for chronic subdural hematoma (CSDH) treatment. Technical and angiographic benchmarks to guide procedural and clinical success are less well established.

METHODS

A single-center database was reviewed to compare outcomes after standalone MMAE with and without resultant residual angiographic opacification of frontal and parietal (F/P) branches. Primary outcome was surgical rescue for CSDH progression. Secondary outcomes included the efficiency and accumulated efficacy of hematoma resolution. Effect sizes were adjusted via multivariable regression.

RESULTS

Of 147 standalone MMAE for CSDH, the overall rate of surgical rescue was 6.8%. Nonopacification of F/P branches via proximal middle meningeal artery or meningo-ophthalmic anastomosis was achieved after 83% of procedures and was associated with a 7-fold decreased rate of surgical rescue (3.3% vs. 24%, P = 0.001). At 90-day follow-up, a higher rate of hematoma resolution ≥50% was achieved if no residual opacification was identified (82% vs. 56%, P = 0.03). The median time to 50% hematoma resolution was 44 days for the no-residual group versus 71 days for the residual group (P < 0.001). The unfavorable effects of residual opacification of F/P branches were verified in a multivariate analysis: a higher risk of surgical rescue (adjusted odds ratio 24.6; P = 0.001) and poor hematoma resolution were both confirmed (adjusted hazard ratio 0.3; P = 0.001).

CONCLUSIONS

MMAE with nonopacification of F/P branches was associated with augmented efficacy. Nuanced MMAE adequately tackling culprit dural feeders should be considered for more effective procedures.

Impact of Embolisate Penetration, Type, and Technique on Results After Standalone Middle Meningeal Artery Embolization for Chronic Subdural Hematoma

BACKGROUND AND OBJECTIVES

Middle meningeal artery embolization (MMAE) has emerged as a promising modality for chronic/subacute subdural hematoma treatment; however, consensus regarding embolization technique and embolisate has not been achieved. We thus sought to compare the efficacy of distinct MMAE techniques and embolisate.

METHODS

An institutional registry was reviewed to identify patients undergoing standalone MMAE for symptomatic chronic/subacute subdural hematoma. Surgical rescue rate and time preceding 50% hematoma resolution were evaluated across 3 technical groups: aggressive penetration (AP), nonaggressive penetration with proximal coil embolization (NP-PC), and nonaggressive penetration alone (NP). Effect sizes were adjusted for demographic, neurological and radiological features through multivariable logistic and Cox regression.

RESULTS

Among 117 procedures, 33.3% achieved AP, 36.8% had NP-PC, and 29.9% had NP. The rate of surgical rescue was 2.6% after AP, 9.3% for NP-PC, and 11.4% for NP. In patients not undergoing rescue surgery, 82.4% achieved hematoma resolution ≥50% at a median imaging follow-up of 56 days; AP or NP-PC were each statistically significantly associated with enhanced hematoma resolution as compared with NP ( P = .02). Similarly, sensitivity analysis within medium-size hematoma and antiplatelet/anticoagulation-at-admission subgroups revealed a superiority of resolution after AP or NP-PC. A unique, comparative secondary analysis of liquid embolisate (Onyx vs n-butyl cyanoacrylate) revealed no impact on rate of surgical rescue or hematoma resolution.

CONCLUSION

AP was associated with the lowest rate of surgical rescue, while both AP and NP-PC were associated with improved rates of hematoma resolution.

Penetration of Non-Adhesive Gel-like Embolic Materials During Dural Vessels Embolization According to Characteristics of Tantalum Powder

Tantalum powder is included in the composition of Non-Adhesive Gel-like Embolic Materials (NAGLEMs) for X-ray opacity. The duration of X-ray opacity during embolization is primarily associated with the particle size, which differs in the most used NAGLEMs-ONYX (Medtronic) and SQUID (Balt). NAGLEMs are widely used for the embolization of branches of the middle meningeal artery (MMA) in patients with chronic subdural hematomas (CSDHs). Considering the size (5-15 microns) of the target dural vessels, we assumed that not only the viscosity of NAGLEMs, but also the size and shape of tantalum granules may be important for the penetration of these gel-like embolic agents and determine their behavior. A notable discrepancy in size was observed. The medium-sized granules in the SQUID 18 sample (0.443 ± 0.086 microns, M ± SD) were found to be approximately ten times smaller than the tantalum granules in the ONYX 18 sample (5.2 ± 0.33 microns, M ± SD).Tantalum granules in SQUID 18 have a regular spherical shape; in ONYX 18 they have an irregular angular shape. When comparing the behavior of gel-like embolic agents of the same viscosity during MMA embolization in patients with CSDHs (an average age of 62.2 ± 14.3 years) in the group where SQUID 18 (n = 8) was used, the gel-like embolic agent in dural vessels demonstrated significantly greater penetration ability compared with the group where ONYX 18 (n = 8) was used. Accordingly, not only the viscosity of NAGLEMs, but also the size and shape of tantalum granules can have a significant effect on the penetration ability of gel compositions.

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.

Simple coiling of middle meningeal artery embolization for chronic subdural hematoma: An inverse probability of treatment weighting matched cohort study

BACKGROUND

Middle meningeal artery embolization (MMAE) for chronic subdural hematoma (CSDH) has gained much attention in recent years. However, unintended embolization may occur when employing liquid embolic agents or particles. We present our clinical experience in simple coiling of MMAE to manage CSDH.

METHODS

Patients underwent either surgical evacuation or MMAE with simple coiling for CSDH were reviewed. Clinical and radiographic outcomes were assessed at admission, 1-month, and 6-month intervals. Two treatment groups were matched with inverse probability of treatment weighting.

RESULTS

One hundred twelve patients were included, with 27 patients in MMAE group and 87 patients in surgery group. In MMAE group, significant reductions were observed in hematoma width (admission vs. 1-month, 2.04 [1.44-2.60] cm vs. 0.62 [0.37-0.95] cm, p < 0.001). The adjusted odds ratio (aOR) of surgical rescue rate (0.77 95%CI 0.13-4.47, p = 0.77), hematoma reduction (>50%) (0.21 95%CI 0.04-1.07, p = 0.06), and midline shift improvement rate (3.22, 95%CI 0.84-12.4, p = 0.09) had no substantial disparities between two groups at 1-month follow-up. In addition, no significant difference was noted between two groups in terms of hematoma reduction (>50%) at 6-month follow-up (aOR 1.09 95%CI 0.32-3.70, p = 0.89). No procedure-related complications were found in MMA embolization group.

CONCLUSION

Simple coiling for MMA had comparable outcomes with surgical evacuation for CSDH. Our findings suggest that simple coiling can be an alternative choice for liquid agents or particles in MMA embolization for CSDH with acceptable safety.

Endovascular treatment for sphenoidal region dural arteriovenous fistula

Sphenoidal region dural arteriovenous fistulas (DAVFs) are rare. Endovascular treatment (EVT) is an effective treatment approach. However, understanding and performing EVT for sphenoidal region DAVFs are difficult and challenging. Therefore, we performed a review to explore this issue further. In this review, we discuss the dural feeders and venous structures of the sphenoidal region, the angioarchitecture of sphenoidal region DAVFs, the role and principle of EVT, various EVT techniques, and the prognosis and complications associated with EVT. We found that various EVT techniques, including transarterial embolization (TAE), retrograde transvenous embolization (TVE), and direct puncture EVT, can be used to treat sphenoidal region DAVFs. TAE represents the most commonly utilized approach. TVE and direct puncture EVT should be limited to highly selective cases. EVT must penetrate the fistula and very proximal venous recipient pouch with a liquid embolic agent or coil the fistula point to have a complete curative effect. Successful EVT can lead to the obliteration of sphenoidal region DAVFs and a good clinical outcome. However, these complications cannot be neglected.

Immediate procedural safety of adjunctive proximal coil occlusion in middle meningeal artery embolization for chronic subdural hematomas: Experience in 137 cases

BACKGROUND

Endovascular embolization of the middle meningeal artery (MMA) has emerged as an adjunctive and stand-alone modality for the management of chronic subdural hematomas (cSDH). We report our experience utilizing proximal MMA coil embolization to augment cSDH devascularization in MMA embolization.

METHODS

MMA embolization cases with adjunctive proximal MMA coiling were retrospectively identified from a prospectively maintained IRB-approved database of the senior authors.

RESULTS

Of the 137 cases, all patients (n = 89, 100%) were symptomatic and underwent an MMA embolization procedure for cSDH. 50 of the patients underwent bilateral embolizations, with 53% (n = 72) for left-sided and 47% (n = 65) for right-sided cSDH. The anterior MMA branch was embolized in 19 (14%), posterior in 16 (12%), and both in 102 (74.5%) cases. Penetration of the liquid embolic to the contralateral MMA or into the falx was present in 38 (28%) and 31 (23%) cases, respectively, and 46 (34%) cases had ophthalmic or petrous collateral (n = 41, 30%) branches. MMA branches coiled include the primary trunk (25.5%, n = 35), primary and anterior or posterior MMA trunks (20%, n = 28), or primary with the anterior and posterior trunks (54%, n = 74). A mild ipsilateral facial nerve palsy was reported, which remained stable at discharge and follow-up. Absence of anterograde flow in the MMA occurred in 137 (100%) cases, and no cases required periprocedural rescue surgery for cSDH evacuation. The average follow-up length was 170 ± 17.9 days, cSDH was reduced by 4.24 ± 0.5(mm) and the midline shift by 1.46 ± 0.27(mm). Complete resolution was achieved in 63 (46.0%) cases.

CONCLUSION

Proximal MMA coil embolization is a safe technique for providing additional embolization/occlusion of the MMA in cSDH embolization procedures. Further studies are needed to evaluate the potential added efficacy of this technique.

Ischemia of the parotid gland and adjacent muscles of mastication following middle meningeal artery embolization

Middle meningeal artery (MMA) embolization is commonly performed as either a first-line or adjunct treatment for chronic subdural hematomas (cSDH). We present the case of a 59 year-old male patient who presented with right hemibody weakness and cognitive impairment and was diagnosed with left-sided cSDH. A left MMA embolization was performed due to the recurrent nature of the chronic subdural hemorrhage and the history of prior craniotomy. On postoperative day 1, the patient developed sudden onset left facial swelling and tenderness, and a contrast computed tomography (CT) of the neck revealed acute ischemia in the left parotid gland, adjacent superior aspect of the left masseter muscle, the left lateral pterygoid, and left temporalis muscles. The patient was treated conservatively with antibiotics, steroids, and analgesics and reported resolution of symptoms on the three-month follow-up. To our knowledge, this is the first reported case of the ipsilateral parotid gland, temporalis muscle, adjacent superior aspect of the masseter muscle, and pterygoid muscle ischemia secondary to non-target particle embolization following MMA embolization in cSDH. Knowledge of normal and variant origin of the MMA and various anastomoses of this vessel with branches of the internal carotid artery (ICA), external carotid artery (ECA), and vertebrobasilar system is crucial to avoid complications during embolization.

Excessive Postoperative Nasal Bleeding Following Septoplasty Caused by a Branch of the Middle Meningeal Artery

Septoplasty is a widely performed procedure globally to correct a deviated nasal septum and improve nasal breathing. Life-threatening nasal bleeding as a complication of septoplasty has been reported in a few cases in the literature. In cases of massive postoperative nasal bleeding, transarterial embolization using angiography was performed for the treatment. This article documents 1 case of excessive postoperative nasal bleeding following an uneventful septoplasty, which was successfully treated with embolization of the frontal branch of the middle meningeal artery. This case represents an extremely rare occurrence, and we present it in conjunction with a literature review.

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.

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 Embolization in the Management of Chronic Subdural Hematoma: a Comprehensive Review of Current Literature

PURPOSE OF REVIEW

Chronic subdural hematoma (cSDH) is a common intracranial hemorrhagic disorder with a high incidence rate among the elderly. While small, asymptomatic cSDH may resolve spontaneously, surgical intervention has been the treatment of choice for larger, symptomatic cases. Surgical evacuation of cSDH may be associated with high rates of recurrence, and even asymptomatic cSDH cases tend to progress. Over the last few years, middle meningeal artery (MMA) embolization has proven to be a safe non-invasive treatment of choice with favorable outcomes and a low recurrence rate. The ensuing paper discusses current treatment modalities for cSDH and reviews existing literature on the anatomy of MMA and its embolization as a treatment option for cSDH.

RECENT FINDINGS

Recent studies show that traumatic head injury leading to subdural hemorrhage can induce neovascularization that may initiate a cycle of recurrent subdural hematoma. Distal branches of MMA supply blood to the dural layers. Several studies have revealed that embolization of the MMA can stop the neovascularization process and blood flow. In addition, patients who underwent MMA embolization had a significantly quicker brain re-expansion and lower recurrence rate. Although the management of cSDH is still very much a dilemma, recent research findings bring MMA embolization to light as a promising treatment alternative and adjunctive therapy.

Subdural evacuation port system and middle meningeal artery embolization for chronic subdural hematoma: a multicenter experience

OBJECTIVE

Middle meningeal artery (MMA) embolization and the Subdural Evacuation Port System (SEPS) are minimally invasive treatment paradigms for chronic subdural hematoma (cSDH). Although SEPS offers acute decompression of local mass effect from a cSDH, MMA embolization has been shown to reduce the rate of cSDH recurrence. In combination, these procedures present a potentially safer strategy to a challenging pathology. The authors present a multi-institutional retrospective case series that assessed the safety, efficacy, and complications of SEPS and MMA embolization for cSDH.

METHODS

A retrospective review was performed of patients who underwent SEPS placement and MMA embolization for cSDH between 2018 and 2021 at three institutions.

RESULTS

One hundred patients with 136 cSDHs and a median age of 73 years underwent both SEPS placement and MMA embolization. Initial Glasgow Coma Scale scores were between 14 and 15 in 81% of patients and between 9 and 13 in 14%. The median initial midline shift (MLS) was 7 mm, with subdural hematoma (SDH) in the left hemisphere (lh) in 30% of patients, right hemisphere (rh) in 34%, and bilateral hemispheres in 36%. Follow-up was available for 86 patients: 93.4% demonstrated decreased MLS, and all patients with lhSDH and rhSDH demonstrated progressive decrease in SDH size. The overall complication rate was 4%, including 1 case of facial palsy and 3 cases of iatrogenic acute SDH. Two subjects (2%) required craniotomy for hematoma evacuation. The rate of good functional outcomes, with modified Rankin Scale (mRS) score < 2, was 89% on final follow-up and the overall mortality rate was 2%. A good mRS score on admission was associated with increased odds of functional improvement at follow-up (p < 0.001).

CONCLUSIONS

SEPS placement with MMA embolization for cSDH can be done safely and effectively reduces cSDH size with minimal perioperative morbidity.

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.

Pharyngo-tympano-stapedial middle meningeal artery variant supply to a falcotentorial dural arteriovenous fistula

The pharyngo-tympano-stapedial middle meningeal artery (PTS-MMA) variant has been described in one case report and never in the setting of arterial supply to a dural arteriovenous fistula, to our knowledge. We report the case of a middle-aged patient with severe, daily headache who presented to our institution for angiography and treatment. CT angiography and MRI demonstrated an enlarged left middle meningeal artery coursing to a large venous varix in the falcotentorial region. Dural arteriovenous fistula was confirmed by subsequent cerebral angiography. Endovascular treatment was performed but without complete obliteration of the fistula. Follow-up angiography demonstrated parasitized arterial supply from a right middle meningeal artery arising from the proximal cervical internal carotid artery coursing through the middle ear consistent with a PTS-MMA variant. The fistula was then treated surgically without recurrence at the 6-month follow-up.