Introduction Endovascular embolization in the external carotid artery territory has become a widely accepted treatment for preoperative embolization of head and neck tumors. Tumors about the skull base present a difficult task to the endovascular surgeon because of extent of disease at presentation, and proximity to foramina with transiting cranial nerves and important blood vessels. External carotid to intracranial artery communications present potential for disastrous complications during embolization procedures. Understanding embryology and regular review of high quality images clearly demonstrating these communications are key to real time recognition during embolization and thus avoiding potential complications.

Methods Retrospective institutional review of endovascular embolization for tumors and vascular malformations about the skull base. Illustrative cases demonstrating dangerous extracranial-intracranial anastamoses and cranial nerve blood supply were identified are presented for review.

Findings Pre-embolization identification and or exclusion of dangerous extracranial to intracranial anastamoses and blood supply to cranial nerves was possible in all cases. Angiographic identification of these vessels facilitated appropriate vessel selection and catheter positioning for safe embolization.

Conclusion Real time ability to identify external carotid territory artery to intracranial artery anastamoses and blood supply to cranial nerves about the skull base allows for effective embolization and avoidance of associated complications from inadvertent vessel embolization.