In June 1973, Professor George Austin invited a small group of neuroscientists from Asia, Europe, the United States, and Canada to the Loma Linda University School of Medicine in Loma Linda, California. The fundamental technique of fashioning a small vessel collateral to the brain had been pioneered by Donaghy and Yasargil 5 years before and was now gaining momentum with the increased availability of the operating microscope, fine instruments and sutures, and surgeons trained in microvascular surgery. The interchange of ideas at this first conference was magic. The handful of participants returned home stimulated with new ideas of technique, patient selection, and postoperative evaluation and resolved to meet again on a regular basis. A Second International Symposium was hosted by Howard Reichman at Loyola University in Chicago, Illinois in June of 1974; a Third Symposium at Rottach-Egern, West Germany in June of 1976 under Professor F. Marguth of the Ludwig-Maximilians-University of Munich.

Cerebral stroke is a common and widespread phenomenon affecting a large number of the human population worldwide. Various surgical methods have been developed for its treatment and the therapeutic results have steadily improved. This is a reassuring trend that promises further progress will be made in the future. This volume contains important contributions by leading clinicians and researchers in the field to the "International Symposium on Surgery for Cerebral Stroke" held in Sendai, Japan, May 24 - 27, 1987.

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.