Isosorbide Nitrate-Assisted Microcatheter Navigation for Successful Embolization of a Foramen Magnum Dural Arteriovenous Fistula

This case report describes the use of pharmacologic vasodilation with intra-arterial isosorbide dinitrate to facilitate endovascular treatment of a foramen magnum dural arteriovenous fistula in a man in his 40s. The fistula was supplied by the posterior meningeal artery arising from the right vertebral artery and the hypoglossal branch of the ascending pharyngeal artery (APA). Catheterization of the APA was challenging due to its tortuous course and small caliber. To address this, 2 mg of isosorbide dinitrate was administered intra-arterially, resulting in effective vasodilation and allowing smooth microcatheter navigation. Embolization was then successfully performed using 12.5% n-butyl-2-cyanoacrylate, leading to a significant reduction in shunt flow. Follow-up angiography at three months confirmed complete obliteration of the fistula, and the patient remained neurologically intact, with no perioperative or delayed complications. This case highlights the potential utility of intra-arterial vasodilators, such as isosorbide dinitrate, in overcoming anatomical challenges during transarterial embolization and suggests their broader applicability in complex neuroendovascular procedures.