Abstract
The pterional approach including subfrontal approach and transsylvian approach that Yasargil advocated in 1984 is most well known and popular approach for neurosurgeons. The distal transsylvian approach, which we usually perform for the aneurysm of internal carotid, middle cerebral and basilar bifurcation, is a modified approach of Yasargil's transsylvian approach. The key points of distal transsylvian approach are preserving all veins, and beginning dissection from the most distal area of the sylvian fissure where the frontal, temporal, and parietal lobes face each other. To preserve all vessels including pial capillary vessels, a precise and meticulous sharp dissection technique is required under a highly magnified microscopic operative field. It should be noted that indirect injury of the pia mater or pial vessels can be caused by an inappropriate tension to the brain or direct injury can be caused by cutting of arachnoid trabeculae because of poor visability.
We describe several microsurgical technical points for the less invasive distal sylvian approach and considerations about the mechanism of damaging pial vessels and pia mater.
