[Blister-like aneurysm of anterior wall of the internal carotid artery, non related to arterial branches. Case report and review of literature].

The authors present (for the first time in polish medical literature) a case of a 41-year old woman, presenting with subarachnoid haemorrhage due to ruptured blister-like aneurysm of the anterior wall of internal carotid artery, unrelated to any arterial branches. The patient was successfully treated surgically (clipping below the aneurysm base within the margin of normal parent artery wall). The authors present diagnostic and therapeutic difficulties of the case, which are characteristic of this type of aneurysms: 1. difficulty to diagnose the aneurysm in angiography (small size and blister-like shape) 2. high risk of massive bleeding and high surgical risk (danger of whole arterial wall rupture). 3. specific surgical approach and technique: subpial dissection of the dome, use of clipgraft, or positioning the clip branches below the base of aneurysm within the margin of normal arterial wall (as the aneurysm dome is composed exclusively of adventitia and is not a part of artery wall. The authors discuss the peculiarities concerning the nature, localisation and possible mechanism of formation of this rare type of aneurysms. The analysis is based on the present case and on the review of literature.