The small neck of the aneurysm afforded an easy surgical attack. An ordinary flat silver clip was placed over the sac and tightly compressed obliterated it completely. The clip was flush with the wall of the carotid artery. The sac, lateral to the silver clip, was then picked up with the forceps and thrombosed by the electocautery. Walter Dandy reporting his successful operation of a posterior communicating aneurysm on March 23, 1937. Walter Dandy's patient left the hospital in good health 2 weeks later, and from his report one may gain the impression that the operation was an easy task. Despite continuous developments during the following decades, it was not until the introduction of the operating microscope and microsurgical techniques that surgical treatment was generally accepted. During the microsurgical era surgical results have continued to improve due to diagnostical, neuroanaesthesi ological, and microsurgical refinements, and improved neurointensive care. Endovascular obliteration has become an important treatment alternative but this has not been included in this particular volume. The purpose of the present supplement of the ACTA NEUROCHIRURGICA is to review some of the elements in the neurosurgical management of patients with aneurysmal subarachnoid haemorrhage that are important for a successful outcome. Professor Helge Nornes has been a major force in the development of new techniques and research strategies in this area for a number of years and has recently retired from the National Hospital in Oslo."

The small neck of the aneurysm afforded an easy surgical attack. An ordinary flat silver clip was placed over the sac and tightly compressed obliterated it completely. The clip was flush with the wall of the carotid artery. The sac, lateral to the silver clip, was then picked up with the forceps and thrombosed by the electocautery. Walter Dandy reporting his successful operation of a posterior communicating aneurysm on March 23, 1937. Walter Dandy's patient left the hospital in good health 2 weeks later, and from his report one may gain the impression that the operation was an easy task. Despite continuous developments during the following decades, it was not until the introduction of the operating microscope and microsurgical techniques that surgical treatment was generally accepted. During the microsurgical era surgical results have continued to improve due to diagnostical, neuroanaesthesi ological, and microsurgical refinements, and improved neurointensive care. Endovascular obliteration has become an important treatment alternative but this has not been included in this particular volume. The purpose of the present supplement of the ACTA NEUROCHIRURGICA is to review some of the elements in the neurosurgical management of patients with aneurysmal subarachnoid haemorrhage that are important for a successful outcome. Professor Helge Nornes has been a major force in the development of new techniques and research strategies in this area for a number of years and has recently retired from the National Hospital in Oslo."

Every few years a dissertation comes to the area of clinical application of medical technology which carries us forward as on a magic carpet into new regions of understanding and patient care. This book is such a magic carpet. It brings together, in a clear and incisive fashion, important hemodynamic principles with a simple noninvasive method of application to a part of the cerebral vasculature which has been relatively inaccessible. To the lucky and perceptive person who reads this book, a feeling of excitement and hope for progress is engendered. The diligent application of the potentials of transcranial Doppler ultrasound brings new power to our efforts in understanding the cerebral circulation and the causes, treatment and prevention of cerebrovascular disorders. Merrill P. Spencer, M. D. Director Institute of Applied Physiology and Medicine Seattle, Wash. , July 1986 Acknowledgements I am greatly indebted to Prof. He1ge Nornes, Oslo, who introduced me to the fascinating study of cerebral hemodynamics in the early 1970's and since then continually encouraged my interest in this field. It was through his pioneering work on the cerebral circulation-using peroperative electromagnetic flowmetry and Doppler techniques-that the basis was laid for the noninvasive trans cranial approach to the circle of Willis described in this book. I also gratefully acknowledge the stimulating case discussions with Prof. Peter Huber, Berne, at the very early introduction of trans cranial Doppler, the inspiring exchange of ideas with Dr. Merrill P.