Transsylvian approach to the tentorial hiatus--anatomical remarks on the microsurgical exposure

A. The transsylvian approach: 1. Splitting of the arachnoid frontally to the medial superficial cerebral vein. 2. Incision of the arachnoid from laterally to medially. 3. Deep dissection frontally to the branches of the middle cerebral artery. 4. Cutting of medial and lateral bridging veins. 5. Spreading of the sylvian fissure. 6. Depending on the length of the intraarachnoidal part of the internal carotid artery and of the posterior communicating artery the alternatives are either subfrontal or subtemporal. B. Through this approach, access to the rostral half of the tentorial hiatus is possible. Also structures which are contralateral to the craniotomy can be reached.