There are three main types of brain death:
1. Cortical or cerebral death:
- Results in a vegetative state where there’s a total loss of power of perception by the senses, but respiration continues because the brainstem is intact.
- This state can be induced by cerebral hypoxia, toxic conditions, or widespread brain injury.
- A person in a persistent vegetative state (PVS) may breathe spontaneously, open and close eyes, swallow, and make facial grimaces. However, there is no meaningful interaction with the environment or evidence of awareness.
2. Brainstem death:
- The victim is irreversibly comatose and incapable of spontaneous breathing due to the loss of brainstem functions.
- Key structures affected in brainstem death include the ascending reticular activating substance (ARAS), paramedian tegmental area, cranial nerve reflexes, and reticular formation.
- Brainstem death is recognized as the stage at which all functions of the brainstem have permanently and irreversibly ceased.
3. Whole brain death:
- Involves the permanent cessation of all functions of the cerebral cortex, cerebellum, and brain stem.