American Academy of Neurology Guidelines for Brain Death Determination

Many of the details of the clinical neurologic examination to determine brain death cannot be established by evidence-based methods. The detailed brain death evaluation protocol that follows is intended as a useful tool for clinicians. It must be emphasized that this guidance is opinion-based. Alternative protocols may be equally informative.

The determination of brain death can be considered to consist of the following steps: I. The clinical evaluation (prerequisites).

A. Establish irreversible and proximate cause of coma.

The cause of coma can usually be established by history, examination, neuroimaging, and laboratory tests.

Exclude the presence of a CNS-depressant drug effect by history, drug screen, or, if available, drug plasma levels below the therapeutic range. Prior use of hypothermia (e.g., after cardiopulmonary resuscitation for cardiac arrest) may delay drug metabolism. The legal alcohol limit for driving (blood alcohol content 0.08%) is a practical threshold below which an examination to determine brain death could reasonably proceed.

There should be no recent administration or continued presence of neuromuscular blocking agents (this can be defined by the presence of a train of 4 twitches with maximal ulnar nerve stimulation).

There should be no severe electrolyte, acid-base, or endocrine disturbance. Achieve normal core temperature.

In most patients, a warming blanket is needed to raise the body temperature and maintain a normal or near-normal temperature (36°C).

B. Achieve normal systolic blood pressure.

Hypotension from loss of peripheral vascular tone or hypovolemia (diabetes insipidus) is common; vasopressors or vasopressin are often required. Neurologic examination is usually reliable with a systolic blood pressure 100 mm Hg.

C. Perform 2 neurologic examinations

Legally, all physicians are allowed to determine brain death in most US states. Neurologists, neurosurgeons, and intensive care specialists may have specialized expertise. It seems reasonable to require that all physicians making a determination of brain death be intimately familiar with brain death criteria and have demonstrated competence in this complex examination. Brain death statutes in the United States differ by state and institution. Some US state or hospital guidelines require the examiner to have certain expertise. The clinical evaluation (neurologic assessment).

A. Coma.

Patients must lack all evidence of responsiveness. Eye opening or eye movement to noxious stimuli is absent. Noxious stimuli should not produce a motor response other than spinally mediated reflexes. The clinical differentiation of spinal responses from retained motor responses associated with

B. Absence of brainstem reflexes.

Absence of pupillary response to a bright light is documented in both eyes.

Absence of ocular movements using oculocephalic testing and oculovestibular reflex testing. Movement of the eyes should be absent during 1 minute of observation. Both sides are tested, with an interval of several minutes.

Absence of corneal reflex. Absent corneal reflex is demonstrated by touching the cornea with a piece of tissue paper, a cotton swab, or squirts of water. No eyelid movement should be seen.

Absence of facial muscle movement to anoxious stimulus.

  Absence of the pharyngeal and tracheal reflexes. The pharyngeal or gag reflex is tested after stimulation of the posterior pharynx with a tongue blade or suction device. The tracheal reflex is most reliably tested by examining the cough response to tracheal suctioning. The catheter should be inserted into the trachea and advanced to the level of the carina followed by 1 or 2 suctioning passes.