[Evaluation of ruptured cerebral aneurysms under 5 mm in size on 3D-rotation angiography]

According to the recent guideline of the Japanese Society for Detection of Asymptomatic Brain Diseases, it should be considered that the operative indication for unruptured cerebral aneurysms is larger than 5 mm, but we have often encountered patients with subarachnoid hemorrhage (SAH) caused by small ruptured cerebral aneurysms. The aim of our study was to evaluate retrospectively the characteristics of ruptured cerebral aneurysms under 5 mm in size on 3-dimensional digital rotation angiography (3D-RA). Eighty patients who presented with acute SAH caused by ruptured aneurysms were admitted in our hospital between January 2003 and September 2007. All patients were examined with 3D-RA and divided into two groups by aneurysmal size; group A was under 5 mm (N = 18), group B was larger than 5 mm (N = 62). Of aneurysms under 5 mm, 45% were located in the anterior communicating artery or anterior cerebral artery, 78% were female and 78% were treated with clipping. Clips of mini and/or the slim type were often applied for aneurysmal clipping. 3D-RA images were useful not only in identification of smaller aneurysms, but also in assessing aneurysmal morphology and relationships to neighboring vessels. However, in the cases of small aneurysms, it is necessary to remember that aneurysms become blood blister-shaped or thrombosed. The clipping for the aneurysm should be performed with consideration of choice for clips consisting of various types according to aneurysmal morphology.