Objective: To evaluate whether current clinical criteria and confirmatory tests for the diagnosis of 'brain death' satisfy the requirements for the irreversible cessation of all functions of the entire brain including the brainstem.
Data sources: Medical, philosophical and legal literature on the subject of 'brain death'.
Data extraction/synthesis: We present four arguments to support the view that patients who meet the current operational criteria of 'brain death' do not necessarily have the irreversible loss of all brain (or brainstem) functions. First, many clinically 'brain-dead' patients maintain residual vegetative functions that are mediated or coordinated by the brain or the brainstem. Second, it is impossible to test for any cerebral function by clinical bedside exam, because the tracts of passage to and from the cerebrum through the brainstem are destroyed or nonfunctional. Furthermore, since there are limitations of clinical assessment of internal awareness in patients who otherwise lack the motor function to show their awareness, the diagnosis of 'brain death' is based on an unproved hypothesis. Third, many patients maintain several stereotyped movements (the so-called complex spinal cord responses and automatisms) which may originate in the brainstem. Fourth, not one of the current confirmatory tests has the necessary positive predictive value for the reliable pronouncement of human death.
Conclusion: According to the above arguments, the assumption that all functions of the entire brain (or those of the brainstem) in 'brain-dead' patients have ceased, is invalidated. Reconsideration of the current concept of 'brain death' is perhaps inevitable.