The literature concerning cerebral circulation, its control, its relation to the metabolism of the brain and its disorders, including cerebral ischemia, is very large and reflects an interest which goes back to Greek and Arabian medicine and which has greatly intensified, particularly over the past decades. Data of the literature remain, however, too sparse to propose a pragmatic approach to cerebral ischemia when affecting people at young age. The first purpose of this monograph has been therefore to bring together from such a literature a coherent account of how present concepts and approaches have developed. In this, the authors have been guided by what seems to be the important lines of investigation. Secondly, the evidence from studies which form the basis of the present understanding has been reviewed critically and, where possible, an attempt has been made to pose present controversies in terms which would be helpful in everyday clinical practice.