[Research in risk assessment in neurosurgery]

Since the time of Hippocrates patients and their physicians have been highly interested in knowing whether, and with what degree of probability "undesirable events" will occur in the course of illness--whether without, in spite of, or because of therapy. In surgery especially, the concept of "risk" is a familiar one to all concerned. The present paper describes traditional and modern methods of quantifying risk and the goals of medical risk research. Application of the results of such research in practice is discussed and illustrated by examples from publications and the authors' own clinical research.