RESUMEN
Preoperative embolization for highly vascularized and large meningiomas is an indispensable technique for facilitating their surgical removal by decreasing blood loss during the operation. This is a report of 4 large and highly vascularized meningiomas in the skull base, on which embolization of feeders was performed preoperatively by PVA (Polyvinyl alcohol foam) particles (150-250 micron produced by INGENOR CO, Paris) and small strips of gelfoam (0.5 x 0.5 x 3-5mm). Under EEG monitoring, Isosorbide dinitrate was used for prevention and relief of vascular spasm. Lidocaine injection tests (Xylocaine 2%: 50mg mixed in equal volumes with Iopamiron 300) were performed for checking before embolization. In the intracranial portion, standard taper steerable guide wire was changed to seeker flexible soft-tip guide wire. In two cases, the meningioma was located in the medial part of the sphenoidal ridge. In the other two cases, one meningioma was in the lateral part of the sphenoidal ridge and the other was in the olfactory groove. In all 4 cases, we successfully performed embolization without complication. In one case, we had to perform embolization twice, because of revascularization detected by angiography 3 weeks after the first embolization. In this latter case, we had performed central embolization only, by using PVA particles, having left feeder without occlusion (peripheral embolization) using gelfoam. The result suggested that it was also necessary to perform peripheral embolization especially if the tumor is fed by large tortuous and irregular abnormal vessels. Peripheral embolization may prevent PVA particles from washing out and causing progressive thrombosis by PVA particles.(ABSTRACT TRUNCATED AT 250 WORDS)