Abstract
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.
Introduction
Middle meningeal artery (MMA) embolization for subdural hematomas (SDH) and dural arteriovenous fistulas (dAVFs) has gained momentum in the neuroendovascular space with the advent of new embolization materials and techniques. The goal of MMA embolization in the context of SDH is to reduce or block the blood supply of the bleeding source thus reducing hematoma growth. 1 In the case of dAVFs, the goal of MMA embolization is to occlude or reduce the abnormal connections between arteries and veins within the dura mater.2,3 Three trials—EMBOLISE, MAGIC-MT, and STEM—showed that MMA embolization may potentially be beneficial in reducing recurrence or progression of chronic SDH. 4 However, there are presently no guidelines on the management of chronic SDH and no consensus on the best approach for MMA embolization due to insufficient research in this domain. A typical approach involves obtaining arterial access (radial or femoral), navigating a guiding catheter through the arterial system into the external carotid artery (ECA), followed by advancing a microcatheter over a microwire to the MMA to identify abnormal blood flow and collateral vessels. Lastly, embolization of the artery takes place using embolic agents (coils, particles, or liquid embolic agents) to block or reduce blood flow.5–10
In bridging the existing knowledge gap, we acknowledge that while literature extensively describes the composition and characteristics of embolic materials,11,12 there is a noticeable scarcity of data addressing catheter attributes specifically tailored for MMA access. To address this void, our study introduces an innovative application of the Zoom™ 45 catheter (Imperative Care, Inc., Campbell, CA), originally designed for revascularization in large-vessel occlusion-associated ischemic stroke. 13
Our investigation aims to shed light on its feasibility, safety, and efficacy in facilitating MMA access for embolization procedures related to SDH and dAVFs.
Methods
Study design and criteria
In this cohort study, we retrospectively analyzed all cases of MMA embolization for SDH and dAVFs using the Zoom™ 45 catheter, in a single-center institution from February 2021 to March 2023. The study protocol was approved by the Institutional Review Board and need for informed consent was waived given the retrospective nature of the analysis.
Eligible patients were treated by a neuroendovascular specialist and included 32 patients ≥ 18 years with SDH or dAVF, treated exclusively with the Zoom™ 45 catheter in attempt to improve distal access. We reviewed and collected data from electronic medical records, including imaging, procedural information, and clinical outcome measures. The primary outcome was technical success, defined as accessing beyond the origin of the MMA without conversion to a different intermediate catheter. Secondary outcomes included ability to identify dangerous collaterals (e.g. petrous and lacrimal branches), selective embolization into distal branches, recurrence of SDH requiring repeat embolization or neurosurgical evacuation prior to discharge, in-hospital mortality, and access site complications and other procedure-related complications.
Data were analyzed using descriptive statistics via STATA/MP Version 14.1 (College Station, TX). Absolute counts and proportions were used for categorical data. We presented non-normally distributed data as median values with interquartile range.
Zoom™ 45 catheter device description
The Zoom™ catheter is a reinforced, single-lumen tube with variable stiffness and a beveled tip, designed for thrombus removal in neurovasculature. 14 It features a distal inner diameter of 0.045 inches and a length of 144 cm, along with a hydrophilic coating aimed at enhancing navigation through the vasculature. The distal beveled tip ensures gentle tracking through neurovasculature and vessel branch points. Additionally, a radiopaque marker facilitates visual confirmation of accurate placement in the target vasculature. The potential benefits of the Zoom™ 45 catheter include enhancing angiographic identification of anastomoses and facilitating easier distal access into the MMA for the operator. The combination of its 0.045-inch distal inner diameter and 0.056-inch distal outer diameter provides improved support and compatibility with delivery microcatheters.
Zoom™ 45 technique for distal access
For our cohort, the ECA is catheterized by the 5F/6F Penumbra Select Catheter (Penumbra Inc., Alameda, CA), then a roadmap is obtained to visualize the vasculature extending to the skull base. We advance the 0.038-inch GLIDEWIRE® Hydrophilic Coated Guidewire (Terumo, Tokyo, Japan) into the internal maxillary artery (IMAX) branch of the ECA. Subsequently, the guide catheter is advanced over the Penumbra Select Catheter and Guidewire into the IMAX as close as possible to the origin of the MMA. Subsequently, the Penumbra Select Catheter and Guidewire are removed. Once our guide catheter is positioned close to the MMA origin, a 12/14 Hybrid Guidewire (Balt, Montmorency, France) and an Apollo™ Onyx™ delivery microcatheter (Medtronic, Irvine, CA) are inserted into the Zoom™ 45 catheter; this system is then introduced within the guide catheter. A roadmap is then utilized to access distally into one of the branches of the MMA with the microcatheter/microwire system; this system will be used as a railway to push the Zoom™ 45 catheter into the stem of the MMA. The microwire and microcatheter system are then removed and a demagnified angiographic anteroposterior and lateral run is then performed to show all branches of the MMA and to better evaluate for any possible dangerous anastomoses. The Zoom™ 45 catheter is then used as an access for multiple microwires/microcatheters to embolize all desired branches of the MMA and to perform adjunctive dextrose 5% push when utilizing TRUFILL™ n-butyl cyanoacrylate (n-BCA) Liquid Embolic System (CERENOVUS, Irvine, CA) as the main agent for embolization. The schematic representation in Figure 1 showcases our system.
Schematic illustration showcasing our access system designed for middle meningeal artery (MMA) embolization. It depicts the guide catheter being inserted distally into the internal maxillary artery just before the origin of the MMA, the intermediate Zoom™ 45 catheter (Imperative Care, Inc., Campbell, CA) positioned within the stem of the MMA, and the microcatheter being advanced distally into the anterior branch of the MMA using a double-angle (“J”) microwire.
Results
Patient and procedural characteristics
The patient and procedural characteristics of all included patients are outlined in Table 1. The majority of patients were male (75.0%, 24/32). History of head trauma was seen in 11 patients (34.4%). Fourteen patients (45.2%, 14/31) were on anticoagulation therapy, anti-platelet therapy, or a combination of both. The most common pathology treated in our cohort was subdural hematoma (93.8%, 30/32), 14 of which were bilateral in nature (46.7%, 14/30). The remaining two patients were treated for dAVF (6.3%, 2/32). Twelve patients underwent surgical intervention prior to embolization, either with craniotomy (18.8%, 6/32) or burr hole evacuation (18.8%, 6/32). Bilateral or single MMA embolization was done in 50.0% (16/32) and 50.0% (16/32) of patients, respectively. The most common embolization material was n-BCA (84.4%, 27/32), followed by a combination of n-BCA and coils (9.4%, 3/32), and lastly, the Onyx™ Liquid Embolic System (Medtronic, Irvine, CA) (6.3%, 2/32).
Patient and procedural characteristics (n = 32 cases).
aAvailable only for 5 of 14 patients on anti-thrombotic prior to the subdural hematoma.
AV: arteriovenous; IQR: interquartile range; MAC: monitored anesthesia care; MMA: middle meningeal artery; n-BCA: n-butyl cyanoacrylate; SD: standard deviation.
Outcomes and procedural complications
Technical outcomes and procedural complications are presented in Table 2. Access success was achieved in 93.8% (30/32) of patients, and in most patients (96.9%, 31/32) dangerous collaterals and anastomoses, such as the petrous and lacrimal branches, were identified. There were two patients (6.3%, 2/32) where embolization was not possible with advancement using the Zoom™ 45 catheter technique due to narrow vessel diameter. The Zoom™ 45 catheter was kept adjacent to the stem of the MMA in one patient. The other case was completed using the SOFIA™ 5F Catheter (MicroVention, Inc., Aliso Viejo, CA). No repeat embolization was required prior to discharge, but one patient (3.1%, 1/32) required further neurosurgical evacuation. One patient had a small intraparenchymal hemorrhage within the right medial parietal lobe prior to the procedure and had experienced a right subacute middle cerebral artery territory stroke and a hematoma involving the right cingulate gyrus post-procedurally in the setting of advanced cancer with low platelet count. These events were considered asymptomatic. Additionally, no other venous thromboemboli were detected in this patient. There were no immediate access site complications observed in our patients.
Outcomes and procedural complications.
aNeurosurgical evacuation was required due to lack of improvement in left subdural hematoma.
bIncluding day rehabilitation.
IQR: interquartile range.
Case illustration No. 1
A female in her 80 s with a history of hypertension and diabetes presented with difficulty walking after two falls where she lost consciousness and struck her head. Computerized tomographic (CT) scan of the head showed a predominantly isoattenuating subdural collection extending along the right cerebral convexity and right interhemispheric falx and measuring up to 1.6 cm in thickness overlying the frontal lobe, as well as a left parietal convexity chronic subdural hemorrhage measuring up to 7 mm in thickness. A cerebral angiogram with intention for MMA embolization was planned. The Zoom™ RDL guide catheter was advanced distally in the IMAX, and this system was used to navigate the Zoom™ 45 catheter over a microcatheter and microwire into the stem of the MMA; an angiographic run was then performed through the Zoom™ 45 catheter identifying all the branches and dangerous anastomoses of the MMA (Figure 2a). A 12/14 Hybrid Guidewire and Apollo™ Onyx™ delivery microcatheter were inserted into the Zoom™ 45 catheter and was navigated distally into the MMA branches (Supplemental Video 1). Different Apollo™ Onyx™ delivery microcatheters were used to embolize the anterior (Figure 2b) and then the posterior (Figure 2c) branches of the MMA with TRUFILL™ n-BCA Liquid Embolic System with an adjunctive dextrose 5% push through the Zoom™ 45 catheter, resulting in penetration distally within the MMA branches, and subsequent complete obliteration of the MMA (Figure 2d). A CT of the head 4 months post-embolization showed near-complete resolution of the right cerebral convexity subdural hematoma.
(a) Lateral view of the middle meningeal artery (MMA) with the injection from the Zoom™ 45 catheter positioned into the stem of the MMA. (b) Distal penetration of the n-butyl cyanoacrylate in the anterior versus (c) posterior branches of the MMA with the dextrose 5% push from the Zoom™ 45 catheter. (d) Lateral view of the angiogram of the external carotid artery showing complete obliteration of the MMA.
Case illustration No. 2
A male in his 50s, previously healthy, presented with pulsatile tinnitus and worsening headaches progressing over several weeks. The initial CT of the head did not show any abnormality, but CTA of the head and neck showed a Cognard Type IV dAVF around the left transverse sinus. The decision to embolize the dAVF was made. Angiogram further characterized the Cognard Type IV dAVF to be originating from the left MMA and left occipital artery and draining into the vein of Labbé and the left transverse sinus. The Zoom™ RDL guide catheter was first advanced distally in the IMAX, and this system was used to navigate the Zoom™ 45 catheter over a microcatheter and microwire into the posterior branch of the MMA to better visualize the site of the fistulization pouch (Figure 3a, b). The Apollo™ Onyx™ delivery microcatheter was used over the 12/14 Hybrid Guidewire for better distal access (Figure 3c, Supplemental Video 2). The left internal jugular (IJ) vein was then accessed directly, and a Mustang Balloon Dilatation (Boston Scientific, Marlborough, MA) was introduced over 0.035-inch GLIDEWIRE® Hydrophilic Coated Guidewire (Terumo, Tokyo, Japan) to the left transverse sinus to protect it from any Onyx™ debris during embolization. Onyx™ was then injected at the fistula pouch and deep into the foot of the vein (Figure 3d, e), and a final angiographic run was then performed through the Zoom™ 45 catheter, showing complete obliteration of the dAVF (Figure 3f).
(a) Middle meningeal artery posterior branch access via the Zoom™ 45 catheter to better locate the site of the fistulization pouch. (b) Anteroposterior (AP) angiographic view performed from the Zoom™ 45 catheter from the proximity to the site of the fistula pouch. (c) Distal access of the Apollo™ delivery microcatheter within the draining vein over the 12/14 Hybrid Guidewire. (d) AP and (e) lateral views of the Onyx™ cast at the end of the procedure, occluding the foot of the draining vein. Also note a Mustang Balloon Dilatation (Boston Scientific, Marlborough, MA) inflated into the left transverse sinus to protect the sinus from any Onyx™ debris during the embolization. (f) Final lateral view angiogram through the Zoom™ 45 catheter showing complete obliteration of the arteriovenous fistula.
Discussion
This study highlights the feasibility, safety, and effectiveness of the Zoom™ 45 catheter in improving distal access to the MMA, achieving a high technical success rate with minimal complications. Additionally, the study recognizes the significance of addressing technological design barriers in catheters to prevent the potential risks associated with MMA embolization and dangerous anastomoses.
Distal access considerations
Accessing the MMA and recognizing potentially hazardous collaterals before embolization may present a difficulty. The Zoom™ 45 catheter, characterized by its eponymous 0.045-inch distal inner diameter, facilitates access to the MMA, aligning well with the typical MMA diameters ranging from 0.047 inches (1.2 mm) to 0.071 inches (1.8 mm). 15 In our study, the Zoom™ 45 catheter was able to access the MMA stem except for two cases where the vessel diameter was too narrow for the catheter. In a specific instance, the Zoom™ 45 catheter remained positioned near the origin of the MMA without further advancement, rendering the distal exploration of the MMA technically impractical. In addition to accounting for the narrow distal vasculature, another significant challenge in MMA embolization lies in the difficulty of identifying hazardous anastomoses, primarily attributed to their variable presence along the intracranial course of the MMA. The Zoom™ 45 catheter not only facilitates access to the MMA, improving the visualization of vessels before the MMA's bifurcation point, such as the petrosal and cavernous arteries, but it also streamlines entry into the anterior and posterior divisions of the MMA. For instance, the persistent connection between the MMA and the ophthalmic artery, known as the recurrent meningeal branch of the lacrimal artery, can exist postnatally if the orbital ramus of the stapedial artery does not regress at the level of the superior orbital fissure. 16 In cases where the orbital ramus division occurs within the cranial cavity, it can split into the meningo-lacrimal branch entering through the Hyrtl's foramen, or orbitomeningeal foramen, while the other branch becomes the ethmoido-nasal branch added to the ophthalmic artery.17–19 In rare situations, a direct anastomosis between the MMA and the ophthalmic artery may occur if the ethmoido-nasal branch does not completely regress. 16 Identifying this connection before embolization is crucial, as it can have severe consequences for patients. In our cohort, the Zoom™ 45 catheter allowed for the operator to identify anastomoses and collaterals in the distal space in the majority of patients, except for one case where embolization was performed at the origin of the MMA due to inability to access the MMA stem using the Zoom™ 45 catheter. Given these outcomes, the Zoom™ 45 catheter potentially plays a pivotal role in achieving a distal access point, enabling neurointerventionalists to conduct more effective angiographic runs for better identification of such anastomoses. Moreover, accessing the stem of the MMA with the Zoom™ 45 catheter facilitates easy access to different branches of the MMA with different catheters, which is usually needed when utilizing liquid embolic agents. This can help streamline the procedure and save fluoroscopic time.
Catheter capabilities
The Zoom™ 45 catheter was not specifically intended for MMA embolization but was designed and initially cleared by the United States Food and Drug Administration for access and after that for use in the revascularization of patients with acute ischemic stroke secondary to intracranial large-vessel occlusive disease within 8 h of symptom onset. To the best of our knowledge, the role of the Zoom™ 45 catheter for use in MMA embolization has not been explored. Although there are no published studies directly comparing the efficacy of the Zoom™ 45 catheter in achieving distal access for MMA embolization with other intermediate catheters, the AXS Vecta 46 intermediate catheter (Stryker Neurovascular, Fremont, CA) presents itself as a potential alternative. It features a 0.045-inch distal inner diameter and a 0.056-inch distal outer diameter, making it a conceivable competitor in this regard. While the Zoom™ 45 catheter offers potential benefits by enhancing angiographic identification of anastomoses and facilitating distal access into the MMA for the operator, another advantage lies in its support for distal microcatheter access within the MMA. The 0.045-inch distal inner diameter and 0.056-inch distal outer diameter provides improved support and compatibility with delivery microcatheters, such as the Apollo™ Onyx™ delivery microcatheter, the Marathon™ flow directed microcatheter (Medtronic, Irvine, CA), or the Magic catheter (Balt, Montmorency, France). This adaptability enables the Zoom™ 45 catheter to be utilized in various procedures and for administering different types of embolic agents.
Based on our practice, the proximal stability combined with the distal flexibility of the Zoom™ 45 catheter makes it an ideal intermediate tool for embolization in distal vessels, such as the MMA. However, the guide catheter should ideally be positioned as distally as feasible in the ECA, and the Zoom™ 45 catheter should always be navigated over a microwire and a microcatheter system. Such intermediate system empowers the proceduralist with easy access, especially when multiple microcatheters are needed for different branches embolization procedures. Also, this intermediate system augments the success of distal embolization by ensuring proximal flow arrest. Moreover, facilitating the concurrent infusion of dextrose 5% alongside n-BCA injection through the catheter has proven to be a smoother and more efficient process in our institutional practice. This approach enhances the distal penetration of n-BCA through narrower and more tortuous vasculature. The effectiveness of delivering n-BCA to a distal position has been validated as a superior technique, as evidenced by a study conducted by Moore et al. on transarterial embolization of dAVFs. 20
Outcomes and complications
While studies examining the use of intermediate catheters for distal access in MMA embolization are scarce, there is also a lack of data directly comparing the effectiveness of employing intermediate catheters for this purpose. As previously mentioned, technical success in achieving access beyond the origin of the MMA was observed in 93.8% of our cohort of patients (30/32). There was only one instance where a switch to another intermediate catheter was necessary, because of the angle of entry in the MMA. Although the Zoom™ 45 catheter, originally designed for large-vessel occlusions, could still achieve distal access, there remains a need for technological advancements specifically tailored for the purpose of distal MMA embolization. In our cohort, we did not observe any access site complications, which could be attributed to the systematic use of access site compression devices and other preemptive measures, such as the use of radial artery concoctions. A single complication was noted involving a patient with advanced cancer and thrombocytopenia. The pre-embolization scan revealed a traumatic intraparenchymal bleed in the medial part of the right parietal lobe. Subsequently, the patient experienced a right subacute middle cerebral artery territory stroke and a hematoma involving the right cingulate gyrus after embolization. The family opted for hospice care in alignment with the patient's goals of care. Instances of recurrence necessitating repeated embolization or neurosurgical were infrequent in our patients, aligning with rates observed in prior reports.21,22
Limitations
Our study highlights the importance of developing catheters tailored specifically for achieving distal access, particularly in embolization procedures that demand meticulous visualization of vessel anatomy. While acknowledging the limitations of our study, caution is warranted in extrapolating the clinical applicability of the Zoom™ 45 catheter due to the small sample size and retrospective design, which introduce potential bias. Furthermore, the existing evidence directly comparing the Zoom™ 45 catheter to other catheters for distal access in MMA embolization is lacking. It is also worth noting that our study involved one operator, potentially limiting the generalizability of the results to those less experienced in distal MMA embolization. Despite these limitations, our findings suggest that the Zoom™ 45 catheter holds promise in addressing the need for more distal MMA access, serving an off-label purpose to fulfill an unmet requirement for safer and more effective MMA embolization.
Conclusions
Our study is pioneering in presenting the safety and effectiveness of the Zoom™ 45 catheter in MMA embolization, achieving a high success rate with minimal morbidity. Given the lack of randomized trial evidence supporting techniques, devices, and materials used in MMA embolization, consolidation of observational cohort data, such as these—and comparative analyses—can permit us to better understand optimal treatment strategies for SDH and dAVF. Additionally, there is a need for innovative design approaches to explore distal points in MMA embolization, creating room for advancements in this field.
Supplemental Material
Supplemental Material
Footnotes
Author’s contribution
All authors participated in the research, data collection, provision of critical revisions for content, and/or writing of the manuscript, and all authors approved the final version of the manuscript.
Declaration of conflicting interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Ethics approval
The protocol of this study was approved by the Institutional Review Board, and the need for informed consent was waived.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Data availability statement
Additional data are available upon request from the corresponding author.
Supplemental material
Supplemental material for this article is available online.
References
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