Preoperative Embolization of Intracranial Meningiomas

Abstract

The method and results for preoperative embolization are described in 36 cases with intracranial meningiomas. Embolization materials were injected through a transfemoral catheter, selectively placed in the external carotid artery. Chopped gelfoam served as embolization material in 29 patients and ivalon particles were used in 7 patients. In 19 out of 36 cases the feeding arteries arose only from the external carotid artery system and were completely occluded (complete embolization) except in 3 cases. The remaining 17 cases also had feeders of the tumor capsule or at the site of the insertion arising from the internal carotid artery system (partial embolization). Thirty-three cases were followed by computed tomography (CT) between embolization and operation. Contrast enhancement effect decreased in 10 cases without marked changes in the plain CT. Tumors developed a low density area, which suggested necrosis in 14 cases, and were irregularly enhanced. In 3 out of these 14 cases, a high density area appeared within the low density area, suggesting an intratumoral hemorrhage, but this disappeared within several days. Through intraoperative findings the effectiveness of embolization was graded as very effective (19 cases), effective (14 cases) and ineffective (3 cases). Changes in the follow-up CT were correlated with complete or partial embolization and predicted the effectiveness of preoperative embolization. The location of the meningioma played an important role in the result of embolization. Convexity meningiomas were most commonly indicative of preoperative embolization and good results were achieved. But small convexity meningiomas which should be excised “en bloc” did not benefit from preoperative embolization, if the internal carotid artery system vascularized the tumor capsule. Satisfactory results were achieved in the parasagittal, falx, sphenoidal ridge, posterior and middle cranial fossa meningiomas. Some basal meningiomas tended to diffusely invade the skull and were difficult to reach at operation. This and especially the frequent necessity of piecemeal removal, indicated preoperative embolization with excellent results. Complications of embolization were seen in about 75% of all cases. But serious complications, such as cranial nerve palsy or aggravated neurological deficits due to reflux of emboli into the internal carotid artery system did not develop in this series.