Preoperative Embolization of Skull Base Meningiomas: Outcomes in the Onyx Era

Background Preoperative embolization may facilitate the surgical resection of skull base meningiomas, but its risk-to-benefit profile remains unclear. Several series have described the outcomes of preoperative meningioma embolization with particles, coils and n-butyl cyanoacrylate (nBCA), but no studies to date have investigated the safety and efficacy of Onyx for skull base meningioma embolization. The aim of this retrospective cohort study was to evaluate the outcomes of preoperative embolization of skull base meningiomas using Onyx as the primary embolysate.

Methods We queried an IRB-approved endovascular database for all meningioma patients who underwent preoperative embolization at our institution from 2007 to 2017. Demographic, embolization, and outcome data were obtained from directed chart and imaging review.

Results Of 84 intracranial meningiomas that underwent preoperative embolization, 29 (35%) were located at the skull base. This included 13 sphenoid wing (45%), 6 anterior cranial fossa (21%), 5 petrous (17%), 3 maxillary/infratemporal (10%), and 2 middle fossa (7%) tumors. The median patient age was 53 (range: 30–87) years, and 19 patients (66%) were female. The median tumor size was 44 (range: 3–164) cm³. The number of pedicles embolized was 1 in 21 cases (76%), 2 in 6 cases (21%), and 3 in 1 case (3%). The embolization procedure was aborted in one sphenoid wing meningioma (3%) due to an inability to catheterize the feeding middle meningeal artery (MMA) pedicle. The embolized pedicles included branches of the MMA in 19 cases (66%); internal maxillary artery in 8 cases (28%); ascending pharyngeal artery in 2 cases (7%); and posterior auricular, ophthalmic, occipital, and anterior cerebral arteries each in 1 case (3% each). The embolysates used were Onyx alone in 20 cases (69%); nBCA alone and Onyx + nBCA in each of three cases (10% each); coils + particles in two cases (7%); and Onyx + coils in one case (3%). The median degree of tumor devascularization was 60% (range: 0–90%). The degree of devascularization was ≥ 75% in 13 cases (45%) and ≥ 90% in 3 cases (10%). Significant neurologic morbidity was observed in one patient (3%). This patient had a giant, 101 cm³ sphenoid wing meningioma and required an emergent craniotomy for symptomatic swelling after Onyx embolization through a MMA pedicle. A transient facial palsy after Onyx embolization through a posterior auricular pedicle of a petrous meningioma was also observed in one patient. The operative estimated blood loss during meningioma resection was 400 (range: 100–1,800) mL.

Conclusion For appropriately selected patients with skull base meningiomas, preoperative embolization with Onyx as the primary embolysate can afford substantial tumor devascularization with an acceptable morbidity rate. The use of Onyx should typically be reserved for dural-based pedicles without distal cranial nerve supply. Particular caution should be taken with giant meningiomas due to the risk of swelling from tumor infarction following embolization.