D. Alan Shewmon, MD

For the past 50 years, the medical profession has understood ‘‘brain death’’ to represent the endpoint of a neuropathologic vicious cycle. An initial major brain injury sets off a mutually exacerbating cascade of cerebral edema, increased intracranial pressure, and decreased cerebral blood flow, which advances beyond some point-of-no-return to a state of no cerebral blood flow and total brain infarction (death of the brain, or ‘‘brain death’’).