[Brain death: physiopathology and current diagnostic approach].
The concept of death has undergone many changes in the centuries depending on ages and social contexts. However death has always been identified by heart and respiratory irreversible arrest. In the last 30 years this concept has been suddenly and deeply modified by cardiocirculatory and respiratory support techniques. The real boundary between life and death is cerebral activity. When this latter causes the subject can be considered dead. In the large majority of cases the clinical and this strumental neurological findings are sufficient for the diagnosis of brain death. However in many other cases this diagnosis may be difficult because of problems in the ascertainment of the complete and irreversible lack of cerebral activities. In these cases many an strumental techniques (evoked potentials, Doppler and nuclear medicine studies) can help in the diagnosis.