Accessory meningeal arterial supply to the posterior nasal cavity: another reason for failed endovascular treatment of epistaxis.

A patient with intractable posterior epistaxis was treated with embolization of the ipsilateral sphenopalatine and facial arteries and contralateral sphenopalatine artery. She continued to bleed despite a seemingly adequate embolization procedure. A second angiogram revealed a significant collateral blood supply to the posterior nasal cavity from the accessory meningeal artery not identified during the first procedure. This was then embolized with no further epistaxis encountered. This case demonstrates yet another collateral arterial pathway that might account for a failed embolization.