Endoscopic Transnasal Coagulation of Anterior and Posterior Ethmoidal Arteries before Open Resection of Large Anterior Skull Base Meningiomas: A Novel Combined Approach and Review of Two Illustrative Cases

Introduction: Large anterior skull base (ASB) meningiomas are occasionally highly vascular, and are supplied predominantly by the anterior and posterior ethmoidal arteries which are branches of the ophthalmic artery. Effective preoperative embolization of these lesions is thwarted by concerns of retrograde embolization of the ophthalmic artery with visual loss or blindness. The standard goal of early intraoperative devascularization of these meningiomas at the basal dural attachment is often difficult until there has been substantial tumor decompression. As such, resection of these lesions is often coupled with lengthy operative times and significant blood loss. Endoscopic transnasal approaches provide direct access to the ethmoidal arteries, and ASB meningiomas are largely devascularized early on in the course of surgical resection. However, endoscopic resection of larger ASB meningiomas has been associated with lengthy resection times, subtotal resection, and increased rate of postoperative CSF leak. In an effort to decrease operative time and blood loss we have adopted a surgical strategy that incorporates endoscopic transnasal devascularization of the tumor as a means to complement the strengths of an open surgical approach. We present our institutional experience with two cases in which we treated large (>4 cm) ASB meningiomas with a combined approach—endoscopic transnasal sacrifice of the anterior and posterior ethmoidal arteries followed by open subfrontal resection.

Methods: Two patients with large ASB meningiomas underwent endoscopic transnasal ligation of the bilateral anterior and posterior ethmoidal arteries. Immediately afterwards, both patients underwent a subfrontal approach (one bifrontal craniotomy, one unilateral FTOZ) for tumor resection.

Results: Endoscopic transnasal ligation was performed successfully in both patients. Subsequent surgical resection was completed in ~4.5 hours with an estimated blood loss of 150cc in each case. A complete resection was obtained in one of the patients, and a small dural tail remained in the other (contralateral to the side of approach).

Conclusion: Endoscopic transnasal sacrifice of the anterior and posterior ethmoidal arteries immediately prior to open surgical resection appears to be a safe alternative for resection of large ASB meningiomas and may translate into shorter operative times with lower blood loss. It is a novel strategy that combines the advantages of endoscopic, microscopic, transfacial and transcranial techniques in a single operation.