This volume contains the papers presented at the 26th Annual Meeting of the Deutsche Gesellschaft fUr Neurochirurgie, held in Heidelberg, Western Germany, on May 1-3,1975. Since at recent meetings of the German Neurosurgical Society central pathophysiological problems such as "central dysregulation" and "brain edema" had been discussed extensively, it seemed appropriate to choose another major area of cerebral patho- physiology for the meeting in Heidelberg. CEREBRAL HYPOXIA is, as LANGFITT once emphasized, "the final common denominator" of various cerebral lesions with which the neurosurgeon is confronted every day. Raised intracranial pressure, respiratory disorders and disturbances in systemic arterial blood pressure, etc. may lead, if not treated, to a focal or global lack of oxygen in the brain tissue. Anoxia finally results in cell death and thus in irreversible cerebral damage or even death. Main interest has therefore been focussed on disturbances in cerebral perfusion pressure ("ischemic hypoxia") and in arterial oxygenation ("hypoxic hypoxia"). The importance of cerebral autoregulatory mechanisms protecting the brain against tissue hypoxia, of patho- morphological alterations of the cerebral vessels (e. g. the "no-reflow-phenomenon") in the course of severe hypoxia, and of changes in brain metabolism have been discussed on a large scale. The organizing committee was particularly happy to have obtained internationally well-known scientists who presented their work in the field of cerebral hypoxia.