Abstract
It is well known that the conditions of the superficial sylvian veins vary from patient to patient. But despite this considerable variation, a dissecting method of the sylvian veins in the transsylvian approach has not yet been systematically described. We introduce a simple, systematic 3-step approach, which is similar to the anterior interhemispheric approach by Ito Zentaro.
Step 1: Open the Insular Cistern
The incision of the arachnoid membrane is performed along the temporal side of the sylvian vein, beginning about 5cm distal from the temporal tip. The insular cistern should be exposed, during which time the M2 portion can be identified.
Step 2: Dissect the fissure like opening an envelope with a knife
The vertex of the head is slightly elevated at the beginning of this step. The arachnoid trabecula is incised toward the base of the sylvian fissure from the deep layer to the superficial layer, as if opening an envelope with a knife.
Step 3: Open the Sylvian Vallecula
The vertex of the head is slightly down at the beginning of this step. In this step, the sylvian vallecula should be exposed. Next, the carotid cistern is opened. As a result the M2-M1-ICA is exposed completely.
By using these 3 steps, we dissect the sylvian fissure safely and easily and preserve all sylvian veins to prevent venous infarction.
