Brain death occurs when the brain is totally and irreversibly non-functional. Brain death is caused by not enough blood supply of oxygen which causes the brain cells to die. (OrganDonor.gov Glossary, June 2026)
Irreversible cessation of cerebral and brain stem function; characterized by absence of electrical activity in the brain, blood flow to the brain, and brain function as determined by clinical assessment of responses. A brain dead person is dead, although his or her cardiopulmonary functioning may be artificially maintained for some time. (HRSA/OPTN Patient Glossary, June 2026)