Incidental ethmoidal dural arteriovenous fistula coexisting with a pituitary adenoma exacerbating post-transsphenoidal epistaxis.

A 64 year-old man with pituitary adenoma developed massive epistaxis after an uneventful endoscopic transsphenoidal surgery. Angiography showed extravasation from the sphenopalatine artery, to which embolisation was performed. An incidentally coexisting ethmoidal dural arteriovenous fistula supplied by the ophthalmic artery aberrantly originated from the middle meningeal artery caused increased haemorrhage.