Controversies in the role of preoperative embolization in meningioma management.

The role of preoperative embolization in meningioma management remains controversial, even though 4 decades have passed since it was first described. It has been shown to offer benefits such as decreased blood loss and "softening of the tumor" during subsequent resection. However, the actual benefits remain unclear, and the potential harm of an additional procedure along with the cost of embolization have limited its use to a small proportion of the meningiomas treated. In this article the authors retrospectively reviewed their experience with preoperative embolization of meningiomas over the previous 6 years (March 2007-March 2013). In addition, they performed a MEDLINE search using a combination of the terms "meningioma," "preoperative," and "embolization" to analyze the indications, embolizing agents, timing, and complications reported during preoperative embolization of meningiomas. In this retrospective review, 18 cases (female/male ratio 12:6) were identified in which endovascular embolization was used prior to resection of an intracranial meningioma. Craniotomy for tumor resection was performed within 4 days after endovascular embolization in all cases, with an average time to surgery of 1.9 days. The average duration of surgery was 4 hours and 18 minutes, and the average blood loss was 574 ml, with a range of 300-1000 ml. Complications following endovascular therapy were identified in 3 (16.7%) of 18 cases, including one each of transient hemiparesis, permanent hemiparesis, and tumor swelling. The literature review returned 15 articles consisting of a study population greater than 25 patients. No randomized controlled study was found. The use of small polyvinyl alcohol particles (45-150 μm) is more effective in preoperative devascularization than larger particles (150-250 μm), but is criticized due to the higher risk of complications such as cranial nerve palsies and postprocedural hemorrhage. Time to surgery after embolization is inconsistently reported across the articles, and conclusions on the appropriate timing of surgery could not be drawn. The overall complication rate reported after treatment with preoperative meningioma embolization ranges from as high as 21% in some of the older literature to approximately 6% in recent literature describing treatment with newer embolization techniques. The evidence in the literature supporting the use of preoperative meningioma embolization is mainly from case series, and represents Level III evidence. Due to the lack of randomized controlled clinical trials, it is difficult to draw any significant conclusions on the overall usefulness of preoperative embolization during the management of meningiomas to consider it a standard practice.