This 13th volume of Advances in Neurosurgery presents thos.e papers held at the 35th Annual Meeting of the German Society of Neurosurgery in Hannover, June 13-16, 1984. Of 150 papers submitted, the program com mittee of the Society chose 69 for presentation. I would like to thank Professors Bock, Brock, Jensen, Wenker, and Wlillenweber for their as sistance in the selection. It was the intention of the President of the Congress at this meeting to lay special scientific emphasis on discussion. For this reason the number of papers had to be limited even more than usual in order to give all participants the opportunity for questions and the presenta tion of their own experience. The main topic of the first day was Extra-Intracranial Anastomoses. Here the operative experience and the long-term results of these operations in the German-speaking countries were reviewed. This discussion was preceded a day earlier by a satellite symposium on the possibilities of the prophylaxis and treatment of ischemic neurological deficits fol lowing subarachnoid hemorrhage by means of calcium antagonists. Microsurgery at the Edge of the Tentorium was the second main topic. In co operation with the SOCiety's microneurosurgery working group, only a small number of lectures were planned, but the topic was covered thor oughly in a round-table discussion.