Anterior ethmoidal artery: microsurgical anatomy and technical considerations.

OBJECTIVE: Vascular lesions of the anterior cranial fossa can receive significant blood supply from the anterior ethmoidal artery. Embolization of this blood supply exposes the parent vessel, the ophthalmic artery, to possible embolic complications, which can lead to loss of vision. A study of the microsurgical anatomy can help delineate the course of the anterior ethmoidal artery and find the best points for proximal control of the blood supply to these lesions. Clinical cases are presented to illustrate how lesions with prominent anterior ethmoidal artery feeders are best approached through fronto-orbital single-flap craniotomies.

METHODS: Eight cadaveric dissections to demonstrate the microsurgical anatomy of the anterior ethmoidal artery were performed to study the relevant anatomy. Two clinical cases are presented that demonstrate clinical application of this anatomy through fronto-orbital single-flap craniotomies.

RESULTS: Eight arteries were studied in four cadaveric heads. The dissections show the course of the anterior ethmoidal artery from the ophthalmic artery in the orbit, through the anterior ethmoidal foramen into the ethmoid air cells, to the cribriform plate, where it turns superiorly to become the anterior falx artery. The first surgical case is of a giant tuberculum sellae meningioma that was resected with coagulation and division of the anterior ethmoidal arteries at the anterior ethmoidal foramina at the laminae papyraceae of both medial orbital walls. The second surgical case is of a large deep right frontal arteriovenous malformation that was resected with coagulation and division of the anterior ethmoidal artery at the anterior ethmoidal foramen of the lamina papyracea of the right medial orbital wall.

CONCLUSION: The cadaveric dissections and our surgical experience show that the anterior ethmoidal artery has three important sites for surgical access: 1) the anterior ethmoidal foramen at the lamina papyracea of the medial orbital wall; 2) the anterior ethmoid canal at the lateral ethmoid wall; and 3) extradurally, at the cribriform plate. These three sites are best accessed through a fronto-orbital single-flap craniotomy, which can be unilateral or bilateral, depending on the pathological findings. The described orbital-cranial approach in this article is not being advocated to replace the standard pterional and frontal approaches; rather, we suggest it as an option in these complex cases that require early proximal control of the anterior ethmoidal artery feeders.