Brain Stem Death

Definition

There is only one definition of death – the permanent loss of the capacity for consciousness, combined with permanent loss of the capacity to breathe – but there are three sets of diagnostic criteria.

Brain death (or death by neurological criteria) is the permanent cessation of brain function, whether as a consequence of cardiorespiratory arrest or devastating brain injury, that will produce the permanent loss of the capacities for consciousness and for breathing and thus induce the clinical state of death. Therefore, a diagnosis of permanent cessation of brainstem function means the person has died and allows a competent individual to confirm the person’s death. Though, this is mainly assessed in intensive care settings, it is essential for all acute physicians to have some understanding.

Three things should be noted in this regard:

1. The irreversible loss of capacity for consciousness does not by itself entail individual death. Patients in a vegetative state (VS) or unresponsive wakefulness syndrome have lost this capacity. However, patients with these syndromes are not dead as they have persisting brainstem function, notably some aspects of consciousness (e.g. arousal, wakefulness) and the capacity to breathe. In patients with brain death, they can no longer breath unaided without respiratory support or intrinsically perform other life-sustaining biological interventions. So, within a brief time, even if the patient remained on respiratory support there would be an inevitable deterioration and organ necrosis.
2. The diagnosis of death because of cessation of brainstem function does not entail the cessation of all neurological activity in the brain. What does follow from such a diagnosis is that none of these potential activities indicates any form of consciousness associated with human life, particularly the ability to feel, to be aware of, or to do, anything. Where such residual activity exists, it will not do so for long due to the rapid breakdown of other bodily functions.
3. There may also be some residual reflex movement of the limbs after such a diagnosis. However, as this movement is independent of the brain and is controlled through the spinal cord, it is neither indicative of the ability to feel, be aware of, or to respond to, any stimulus, nor to sustain respiration or allow other bodily functions to continue.

Brain-stem death is not part of the VS, which has been defined as a clinical condition of unawareness of self and environment in which the patient breathes spontaneously, has a stable circulation, and shows cycles of eye closure and opening which may simulate sleep and waking.

The current position in law is that there is no statutory definition of death in the United Kingdom. Subsequent to the proposal of the brain death criteria by the Conference of Medical Royal Colleges in 1976, the courts in England and Northern Ireland have adopted these criteria as part of the law for the diagnosis of death. There is no reason to believe that courts in other parts of the United Kingdom would not follow this approach.

Conditions necessary for the diagnosis of death by Neurological criteria:

The Academy of Medical Royal Colleges (AoMRC) recently updated their guidelines on confirmation of death in 2025. [11]

The confirmation of death using neurological criteria is a clinical diagnosis that should be made by at least two doctors who have had full registration with the General Medical Council (GMC) or equivalent international professional body recognised by the GMC for more than 5 years and are competent to diagnose and confirm death using neurological criteria in the UK. At least one of the doctors must be a consultant.

The diagnosis should be undertaken by the two doctors working together but each independently ensuring that the diagnosis is carried out in an accurate, standardised and timely manner. The two doctors then must be satisfied that all the necessary preconditions for the application of neurological criteria are met or can be mitigated by the addition of an ancillary investigation

Specific preconditions must be fulfilled before the two doctors can commence their clinical testing:

• Aetiology severe enough to cause permanent cessation of brainstem function
  • This diagnosis must be evaluated with neuroimaging as a minimum but can also include electrophysiological or invasive intracranial pressure measurements
• Assessment period sufficient to exclude the potential for recovery.
  • In all cases neurological criteria should not be applied until at least 6hrs following the loss of the last observed brainstem reflex or spontaneous breath
  • In the context of post cardiac arrest, neurological criteria should not be applied until at least 24hrs following the loss of the last observed brainstem reflex or spontaneous breath
• Exclusion of potentially reversible factors materially contributing to the coma or apnoea. Examples include:
  • Hypothermia (specifically any temp <36^oC)
  • Depressant/sedative drugs
  • Profound neuromuscular weakness
  • Cervical spinal cord pathology
  • Electrolyte disturbances (specifically sodium, potassium, glucose and phosphate + magnesium)
  • Endocrine disturbances (such as myxoedema or addisonian crisis)
• Additional caution for diagnosing death using neurological criteria in uncommon circumstances.
  • Steroids
  • Primary posterior fossa/brainstem aetiology
  • Therapeutic decompressive craniectomy
  • Children <2yrs old