Brain death - Causes 

Brain stem death can occur when the blood and oxygen supply to the brain is stopped. This can be caused by:

• a heart attack – a serious medical emergency that occurs when the blood supply to the heart is suddenly blocked
• a stroke – a serious medical emergency that occurs when the blood supply to the brain is interrupted
• a blood clot – a blockage in one of your blood vessels that disturbs or blocks the flow of blood around your body

Brain stem death can also occur as a result of:

• a serious head injury
• infections, such as encephalitis (a viral infection of the brain) 
• a brain tumour (a growth of cells multiplying in an abnormal, uncontrollable way in the brain)