Summary: Massive intraoperative hemorrhage during middle ear surgery is unusually rare. The authors describe a case report of the patient operated on suspected glomus tumor. During surgery a significant arterial bleeding occurred when a probatory excision from the suspected tumor had been taken. It was stopped by firm gauze plugging of the external ear canal and nasopharynx. Subsequent angiography showed the anomalous internal carotide artery traversing the middle ear to be a source of bleeding. A pseudoaneurysm of internal carotid artery developed in the middle ear. It was treated by superselective endovascular embolization with coils eleven days after accident. In second stage the tympanic membrane was strengthened by chondroperichondral graft. The patient healed without sequelae. There is only moderate conductive hearing loss on the operated side. The authors submit an overview of the arterial supply of the middle ear, its embryologic development as well as formation of the most important vascular anomalies of the middler ear, namely persistent stapedial artery and abberant internal carotid artery. They stress the meaning of the selective angiography (DSA) of the internal carotid artery and HRCT of the temporal bone evaluated by otologically specialized radiographer.

        Key words: aberrant internal carotid artery, massive hemorrhage from the middle ear, anomalous course of the carotid artery, iatrogenic injury of the internal carotid artery.