Diagnosing brain stem death 

There are a number of criteria for diagnosing brain stem death.

For a diagnosis of brain stem death to be made:

  • A person must be unconscious and fail to respond to outside stimulation.
  • A person's heartbeat and breathing can only be maintained using a ventilator.
  • There must be clear evidence that serious brain damage has occurred and it can't be cured.

Ruling out other conditions

Before testing for brain stem death can begin, doctors must carry out a series of checks to ensure that the symptoms aren't being caused by other factors. For example:

Once these factors have been ruled out, tests are carried out to confirm brain death. The diagnosis of brain death has to be made by two senior doctors. Neither of them can be involved with the hospital's transplant team.

The doctors will explain the tests to you and they will keep you informed about your loved one's condition at all times.

Tests

The doctors will run a series of tests. Both of doctors have to agree on the results for a diagnosis of brain death to be confirmed. The tests are carried out twice to minimise any chance of error.

The tests used to determine whether brain stem death has occurred are outlined below:

  • A torch is shone into both eyes to see if they react to the light.
  • The cornea (transparent outer layer of the eye), which is usually very sensitive, is stroked with a tissue or piece of cotton wool to see if the eye reacts. 
  • Pressure is applied to the forehead and the nose is pinched to see if there is any movement in response.
  • Ice-cold water is inserted into each ear, which would usually cause the eyes to move.
  • A thin, plastic tube is placed down the trachea (windpipe) to see if it provokes gagging or coughing.
  • The person is disconnected from the ventilator for a short period of time to see if they make any attempt to breathe on their own.

Brain death will be diagnosed if a person fails to respond to all of these tests.

Occasionally, a person’s limbs or torso (the upper part of the body) may move, even after brain stem death has been diagnosed.

These spinal reflex movements are generated by the spinal cord and don't involve the brain at all. Therefore, they won't affect the diagnosis of brain death.


Has brain stem death ever been incorrectly diagnosed?

From the available evidence, the answer is no.

In 2010, American researchers checked all available medical literature to see if there has ever been a case of a person recovering after a diagnosis of brain stem death. They were unable to find a single case.

Page last reviewed: 21/05/2014

Next review due: 21/05/2016