This 16th volume of Advances in Neurosurgery contains a selection of papers presented at the 38th Annual Meeting of the German Society of Neurosurgery, held in Munster on 3-6 May 1987. The program committee had to choose these contributions from a total of 161 presentations. I am very much obliged to the members of the committee who contributed their experience and effort to the organization of the scientific pro­ gram: Prof. Dr. R.A. Frowein, Prof. Dr. W.J. Bock, Prof. Dr. E. Kazner, Prof. Dr. G. Lausberg, Prof. Dr. M. Klinger, and Prof. Dr. M. Brandt. The aim of the Meeting was to exchange experiences regarding modern diagnostic and therapeutic achievements. The first main topic was new technical methods in neurosurgery. Refinements in laser technology were introduced; different laser devices have been recognized as use­ ful tools in microsurgery and some peripheral nerve problems. The Ca­ vitron ultrasonic aspirator has proven its value in a great variety of intracranial and spinal tumors within a few years. Its technical advance is impressively demonstrated by some of the papers in this book. With growing experience we have recognized the great value of these additional instruments in limited surgical fields and learned not to overestimate them in the hands of a skilled neurosurgeon.