BACKGROUND Cellulose porous beads (CPBs) are exceptionally uniform in size and nonabsorbable and they provide highly effective tumor devascularization. The risk of cranial nerve palsy must not be overlooked when embolization with CPBs is considered in meningioma patients. We attempted to identify patients at risk of cranial nerve palsy after meningioma embolization. METHODS Prior to preoperative superselective embolization with 200 mum diameter CPBs, 141 patients with meningioma underwent provocation test with lidocaine and amytal. They were divided into two groups on the basis of whether they were or were not considered eligible for embolization. We evaluated the differences between the two groups with respect to tumor anatomy, angiographic findings, and clinical presentation and recorded complications associated with the embolization of the meningioma. RESULTS Of the 141 patients, 128 underwent CPB embolization (group 2); 13 were not embolized because their provocation test results were positive (group 1, n = 11) or because they showed vasospasm (n = 2). Group 1 patients had meningioma in the cavernous sinus or petroclival region. Characteristically, the feeders were of middle meningeal artery origin and exhibited a posteromedial course toward the petrous apex or cavernous sinus. In group 2 patients the middle meningeal artery was the feeder, but it lacked branches coursing posteromedially. Three of these patients experienced complications which included intratumoral hemorrhage (n = 2) and post-embolization hearing disturbance (n = 1). CONCLUSIONS Patients with meningioma whose tumor-feeding arteries run posteromedially toward the petrous apex or cavernous sinus are at increased risk of post-embolization cranial nerve palsy. Appropriate protocols, including lidocaine and amytal provocation tests, may reduce the risk of complications after CPB embolization of the external carotid territory in this group of patients.