Noninferiority of coiling versus coiling with particles in middle meningeal artery embolization: A technical note and case series
Article information
Abstract
Objective
To investigate the possibility of using coils as a standalone treatment for middle meningeal artery embolization.
Methods
Four patients (3 females, 1 male, median age 77.5) with bilateral subdural hematomas were treated with bilateral MMA embolization. One hematoma of each patient was treated with coils and PVA, and the other was treated exclusively with coils. New or resolved symptoms, radiographic imaging demonstrating hematoma change, and complications were recorded and compared between the two treatment modalities. Minimum follow-up time was three months.
Results
All patients demonstrated symptomatic and radiographic improvement at three month follow-up. None of the patients in this cohort received surgical evacuation of the hematoma prior to or after embolization. One patient had previously been treated for hydrocephalus with a VP shunt. There were no postoperative complications. In the hematomas treated with a combination of coils and particles, three showed complete resolution with one showing interval improvement on imaging. All hematomas treated with coils alone demonstrated complete resolution after three months.
Conclusions
Middle meningeal artery embolization with coils alone has demonstrated noninferior results to embolization with a combination of particle embolisate and coils in this small cohort.
INTRODUCTION
Chronic subdural hematoma (SDH) is prevalent in elderly populations with a substantial healthcare burden [8]. Chronic SDH can present with a variety of different symptoms including cognitive impairment, seizures, focal neurologic deficits, altered mental status, gait disturbance, and headache, with mortality estimates for chronic SDH similar to a hip fracture in this population [1,5,7]. The incidence of SDH rose from 26.4 per 100,000 in 2003 to 58.6 per 100,000 in 2016 [7]. With the aging population worldwide, the incidence of subdural hematoma is expected to increase accordingly [7]. The etiology of SDH can be traumatic, iatrogenic, or spontaneous, with antiplatelet and anticoagulant medications playing a role in SDH formation [8,9]. SDH can be treated medically by resolving coagulopathy or discontinuation of anti-platelet or anticoagulant medications, or procedurally with craniotomy or middle meningeal artery embolization [9].
Middle meningeal artery (MMA) embolization is a safe and minimally invasive treatment for chronic subdural hematoma [3,6,10]. MMA embolization disrupts blood supply to the neovascular beds formed as part of the inflammatory response in SDH formation, and it is believed that leakage from these neovascular beds serves as the mechanism for SDH expansion [10]. Patients with significant midline shift or neurologic manifestations may undergo surgical evacuation of their SDH, with or without MMA embolization as an adjunct treatment [10]. For chronic SDH that did not meet operative criteria, MMA embolization can be used as a standalone treatment. MMA embolization is performed using a variety of materials which fall within three categories: particles, liquid, and coils, with different mechanisms of action and demonstrated efficacies [9].
While achieving an optimal microcatheter position for MMA embolization, a nuanced understanding of the patient’s unique anatomy is necessary to minimize risk of intervention. Unrecognized anatomical variants such as ophthalmic anastomoses can lead to postoperative complications and can potentially be avoided by proper selection of both embolization position and embolisate [9,10]. Successful embolization is then confirmed with a follow-up angiogram.
Coiling for middle meningeal artery embolization is used in conjunction with either particle (e.g. polyvinyl alcohol (PVA), embozene) or liquid embolisates (e.g. Onyx, Trufill) [10]. We have previously demonstrated techniques using endovascular coils to augment distal delivery of embolisate for MMA embolization [10]. Liquid embolisate, which embolizes proximally, and particles, which act more distally, have demonstrated similar outcomes with regard to subdural hematoma recurrence, radiation dosage, and median fluoroscopy time [6]. Demonstrating the efficacy of MMA embolization with coils alone could assist in improving neurosurgical techniques and industry development of coiling agents specialized in middle meningeal artery embolization.
CASE DESCRIPTION
We conducted a retrospective review of four consecutive patients with bilateral chronic SDH treated with bilateral MMA embolization at our institution where one side was treated with a combination of coils and PVA particles, and the other side with coils alone. Patients were followed for 3 months at minimum, receiving non-contrast computed tomography (CT) for radiographic evaluation. Patient or family reported symptoms were also evaluated at follow-up appointments. Patient outcomes recorded included radiographic measurements of hematoma size, hematoma recurrence, and new or resolved neurologic deficits. We compared the results and outcomes of the side treated with a combination of PVA and coils to the side treated with coils alone. Demographic information and baseline parameters for the four cases can be found in Table 1.
Demographics and baseline parameters of the four cases. SDH, subdural hematoma; MMA, middle meningeal artery, PVA, polyvinyl alcohol
Description of middle meningeal artery embolization
The patient is moved into the angiography suite, positioned supine on the angiography table, prepped and draped in the usual sterile fashion. Common femoral artery access is achieved via a modified Seldinger Technique, and a 5-French sheath is used to maintain arterial access. The external carotid artery and subsequently the middle meningeal artery are selected using an angled diagnostic catheter and microwire. OmnipaqueTM (iohexol) 240 Iodine contrast (GE Healthcare, Illinois, USA) is used for all angiograms during the procedure, and select angiograms are performed of the middle meningeal artery. After confirming embolization position, most commonly near the foramen spinosum, and observing any anatomically aberrant anastomoses, embolization of the MMA is performed using coils or PVA at the discretion of the attending surgeon. Coils manufactured by Stryker, Medtronic, and Balt were used. Follow-up angiography is performed to confirm complete embolization of the middle meningeal artery. An angioseal closure device (Terumo) or manual pressure are used to close femoral artery access at the end of the procedure. Fig. 1 demonstrates coil placement for embolization of the middle meningeal artery.
Sagittal (A) and coronal (B) angiography demonstrating middle meningeal artery anatomy prior to embolization. Sagittal (C) and coronal (D) angiography demonstrating coil embolization with a PACE 0 score.
Case series
Case 1
A 34-year-old male was found to have bilateral subdural hematomas after workup for traumatic head bleeds when playing soccer. The patient was asymptomatic and thus was offered MMA embolization as minimally invasive management. After discussing the risks and benefits of the procedure, the patient opted for MMA embolization. The patient consented to the procedure.
The right common femoral artery was catheterized, the catheter was navigated to the right external carotid artery, and an angiogram was performed demonstrating proper embolization position. PVA was released to embolize the right middle meningeal artery which was followed by an angiogram. Coils were deployed and two repeat angiograms demonstrated complete occlusion of the right middle meningeal artery. Next, the left external carotid artery was catheterized. It was discovered that the patient had variant anatomy with the frontal branch of the left middle meningeal artery originating from the left ophthalmic artery. Out of concern for possible ophthalmic complications of PVA deployment, the decision was made to embolize using coils only. Following coil deployment, an angiogram demonstrated complete occlusion of the left middle meningeal artery. In total, four Axium Prime 2.5 mm×6 cm coils, two Axium Prime 2.5 mm×4 cm coils, one Axium Prime 2 mm×4 cm coil and one Axium Prime 1.5 mm × 4 cm coils were used for embolization in this patient. The catheter was retrieved, and the femoral access was closed in the standard fashion. Postoperatively, the patient had no complications.
The patient presented to clinic three months postoperatively for follow-up and was asymptomatic at that time. CT head three months postoperatively demonstrated resolution of bilateral subdural hematoma with no other changes present. Preoperative CT, intraoperative fluoroscopy, and postoperative CT imaging are demonstrated in Fig. 2.
(A) Preoperative coronal CT demonstrating bilateral chronic subdural hematomas (B) Postoperative coronal CT demonstrating resolved bilateral chronic subdural hematomas (C) Right middle meningeal artery angiogram prior to embolization. (D) Right middle meningeal artery angiogram post embolization. (E) Right middle meningeal artery angiogram prior to embolization. (F) Right middle meningeal artery angiogram post embolization. CT, computed tomography
Case 2
An 81-year-old female presented with bilateral traumatic SDH which had been conservatively managed. The patient failed conservative management, with repeat imaging demonstrating SDH expansion. The patient was asymptomatic at the time of presentation. The patient was offered minimally invasive management of the bilateral SDH with MMA embolization. After discussing the risks and benefits with the patient, the patient consented to the procedure.
The right common femoral artery was catheterized, and the catheter was navigated to the left external carotid artery, and advanced to the left middle meningeal artery. An angiogram was performed revealing an aberrant origin of the left ophthalmic artery. Out of concern for possible reflux, the decision was made to embolize using coils only. Coils were deployed to embolize the left middle meningeal artery, and complete occlusion was demonstrated via angiogram. Using roadmap guidance, the right external carotid artery was catheterized with angiogram demonstrating proper embolization positioning. 250-micron PVA was deployed for embolization and a follow-up angiogram demonstrated residual flow. A series of coils were deployed for further embolization, and a repeat angiogram demonstrated complete occlusion of the right middle meningeal artery. In total, five 1.5 mm × 4 cm coils, one Axium Prime 2 mm × 8 cm helical coil, two Axium Prime 2.5 mm × 6 cm coils, and two Axium Prime 2 mm × 4 cm coils were used for embolization in this patient. The catheter was retrieved, and the femoral access was closed in the standard fashion.
Postoperatively, the patient had no immediate complications and was discharged on post-op day 2. The patient presented to the ED three weeks postoperatively in status epilepticus. The patient was found to have a urinary tract infection and uncontrolled blood glucose of 363 mg/dL, which was thought to be the etiology of her seizures and was unrelated to recent embolization. The patient presented to clinic four months postoperatively for follow-up with imaging demonstrating resolving bilateral SDH with no new neurologic deficits.
Case 3
A 79-year-old female with a past medical history of a myocardial infarction, congestive heart failure, and hydrocephalus treated at our institution with ventriculoperitoneal shunt placement was found to have expanding SDH on surveillance imaging. After discussing the risks and benefits of the procedure, the patient opted for MMA embolization. The patient consented to the procedure.
The right common femoral artery was catheterized, and the wire and catheter were navigated to the right external carotid artery. An angiogram was performed to demonstrate proper positioning and confirm absence of orbital anastomoses. The right middle meningeal artery was embolized using a combination of 250-micron PVA and coils, with follow-up angiograms confirming complete occlusion of the right middle meningeal artery. The catheter was then navigated to the left external carotid artery, and an angiogram was performed, confirming the absence of orbital anastomoses. The left middle meningeal artery was embolized with a series of coils without usage of PVA. A follow-up angiogram confirmed complete occlusion of the middle meningeal artery. In total, four Complex 10 super soft 2 mm × 6 cm coils, one Complex 10 super soft 1.5 mm × 4 cm coil, one Complex 10 super soft 2 mm × 4 cm coil, one Complex 10 super soft 1 mm ×3 cm coil, one Complex 10 super soft 2.5 mm × 6 cm coil, and two Optimax Complex super soft 2 mm × 6 cm coils were used for embolization in this patient The catheter was retrieved, and femoral access was closed.
Postoperatively, the patient had no complications and was discharged post-op day 1. At her three month follow-up appointment, the patient had only intermittent mild headache with follow-up imaging demonstrating resolved bilateral subdural hematomas.
Case 4
A 76-year-old female with a past medical history of kidney transplant and hypothyroidism presented with slow cognitive decline. CT imaging demonstrated bilateral subacute on chronic subdural hematoma. Due to the patient’s stable condition and progressive symptoms, the patient was offered middle meningeal artery embolization as minimally invasive management. After discussing the risks and benefits with the patient, the patient consented to the procedure.
A right femoral artery access was established, and the catheter was navigated to the right external carotid artery. An angiogram was performed, and the right middle meningeal artery was embolized using 200-micron PVA, followed by coil embolization. Follow-up angiograms demonstrated complete occlusion of the right middle meningeal artery. The left external carotid artery was then catheterized, and an angiogram was performed. The left middle meningeal artery was navigated to and embolized using a series of coils, no PVA was used. Follow-up angiograms demonstrated complete occlusion of the left middle meningeal artery. In total, five Optima coil complex 10 supersoft 1.5 mm × 4 cm coils and six Optima coil complex supersoft 2 mm × 6 cm coils were used for embolization in this patient. The catheter was retrieved, and the femoral access was closed in the standard fashion.
Postoperatively, there were no complications, and the hospital course was unremarkable. The patient was discharged home on postoperative day 1. The patient was seen in telemedicine clinic for follow-up three months later and reported no headaches or dizziness, with mild improvement in cognitive function. CT imaging 3 months postoperatively demonstrated decreasing R parietal collection from 18 mm to 15 mm, with resolved left sided SDH.
DISCUSSION
In this technical case series, we use coils exclusively for MMA embolization, confirmed by angiogram, and demonstrate no difference in patient outcomes compared to MMA embolization with a combination of coils and PVA. We report no complications, new neurologic deficits, or SDH recurrence using this method. While other case series exist demonstrating exclusive coil use in MMA embolization, this is the first reported case series to our knowledge with asymmetric treatment methods demonstrating noninferiority of isolated coil use [4].
MMA embolization has been demonstrated to be a safe and effective alternative to craniotomy for the management of chronic subdural hematoma, especially in elderly patients. Several embolisate combinations and embolization techniques have been previously published, including our group, to increase the efficacy of treating chronic subdural hematoma [10]. Investigations into optimizing variables in middle meningeal artery embolization can further reduce operative complications and recurrence rates, assisting the global burden of chronic SDH.
In cases 1 and 2, asymmetric treatment methods were employed due to variant anatomy resulting in aberrant origins of the ophthalmic artery, and out of concern for reflux resulting in potential ophthalmic complications, the decision to embolize with coils alone and then confirm with an angiogram demonstrated SDH resolution regardless of PVA administration. Treatment of bilateral subdural hematoma in these cases using different treatments for each side allows for each patient to also serve as their own control group, with demonstrated improvement bilaterally in all patients, and in the case of Case 3, complete resolution on the coil only side with interval improvement but not complete resolution on the PVA and coil treatment side. None of the patients experienced neurologic complications in the immediate postoperative period or during follow-up that are related to the procedures.
MMA embolization with endovascular coils alone allows the surgeon to avoid the use of liquid or particle embolisates, each of which carries their own weaknesses. PVA particles carry the risk of ophthalmic complications such as blindness if ophthalmic collaterals exist, which are not always detectable on angiogram [10]. Avoiding this risk and employing coils alone allows for a faster, more targeted operation which eliminates feared complications and decreases operative time. The proposed mechanism for coil-only embolization is eliminating perfusion of the neomembrane by embolizing the middle meningeal artery, most commonly at the foramen spinosum in our institution. We have previously demonstrated that fewer acute products occur when complete embolization occurs at the foramen spinosum, resulting in a PACE score of 0, compared to more distal coiling sites, with consistent radiographic improvement noted for all patients treated via this technique [2]. No differences are observed clinically at our institution with regard to manufacturer of coils.
Limitations
This case series is a small proof of concept and lacks the sample size to derive a failure rate, and a comprehensive list of potential surgical complications, and thus cannot demonstrate safety and efficacy. Further investigation with a larger sample size will be required before any changes to standards of practice should be implemented. Additionally, the patients treated in this case series had relatively small, non-recurrent SDHs and therefore spontaneous resolution of the hematomas cannot be ruled out completely, however in a series of the four cases at our institution of patients treated with bilateral middle meningeal artery embolization and asymmetric embolisates, all hematomas demonstrated improvement regardless of the embolisate used. A case series including patients with both recurrent and larger subdural hematomas would provide additional insight into the extent of coil only embolization efficacy.
CONCLUSION
The use of endovascular coils alone for MMA embolization is a potentially useful technique which eliminates the inherent risks present with other embolisates.
Notes
ACKNOWLEDGMENT
Dr. David R. Santiago-Dieppa, MD FAANS is a consultant for Balt, Stryker, and Medtronic.
Disclosure
The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.