[Evaluation of brain death by computed tomography].

The absence of cerebral circulation and electrocerebral silence have served as an accurate index of irreversible brain death. It is proposed that computed tomography (CT) findings be evaluated as confirmatory criteria of brain death. To this end, CT evaluation of 14 patients satisfying the conventional criteria of brain death was performed. A.CT finding of severe compression or disappearance of the ventricular system, or so-called "brain tamponade", was seen in 7 (50%) of the 14 patients. Enhanced contrast CT, especially dynamic CT, usually distinctly reveals the cerebral vessels whenever the cerebral blood flow is preserved; conversely, the lack of enhanced brain structures, even comparing attenuation values, indicates the absence of cerebral blood flow. In 7 (70%) of 10 patients, however, there was enhanced contrast of vascular brain structures, especially the circle of Willis, major cerebral arteries, choroid plexuses, and venous sinuses. It is suggested that this result is due to the improvement of demonstrability by CT. The usefulness of CT in the confirmation of brain death lies in visualization of the pathological changes associated with a dead brain, such as "brain tamponade", and the lack of enhanced contrast indicating the absence of cerebral blood flow. The latter point is still problematic as angiography revealed an extremely low cerebral blood flow in a few cases of "dead brain" patients. It is recommended that cerebral blood flow in brain death be evaluated by dynamic CT scanning and correlated with other methods of cerebral blood flow determination (e.g., intravenous digital subtraction angiography).