内頚動脈りゅう手術におけるＤｉｓｔａｌ Ｔｒａｎｓｓｙｌｖｉａｎ Ａｐｐｒｏａｃｈのアドバンテージと技術的ポイント−いわゆるＰｔｅｒｉｏｎａｌ Ａｐｐｒｏａｃｈとの違い−

Abstract

The pterional approach includes 2 major approaches: the subfrontal and transsylvian approach. Both approaches are popular operative techniques in neurosurgery. We describe a distal transsylvian approach to internal carotid artery aneurysm that includes the following components: 1) beginning the dissection of sylvian fissure at 5 cm distal from temporal tip, 2) identifying the M3 and/or M2 portion of middle cerebral artery in the insular cistern, 3) cutting arachnoid trabeculle between frontal lobe and temporal lobe from deep area to the surface of sylvian fissure, 4) preserving associating veins along sylvian fissure in order to prevent venous infarction after surgery, and 5) using the extended approach of distal transsylvian approach, which is called the anterior temporal approach. This method results in enhanced exposure with preservation of sylvian veins and minimal retraction of brain. Especially thick subarachnoid blood clots can be evacuated well in the distal sylvian fissure such as the “Sylvian Point” on angiogram. In cases of posterior projected IC-PC aneurysm, the distal transsylvian approach can be converted to the anterior temporal approach, in which it is easy to recognize perforators arising posterior to the communicating artery. This procedure can serve as an alternative to subfrontal approach for subarachnoid hemorrhage or complex IC-PC aneurysms.