Death by Neurological Criteria: A Difficult Concept

2015 - 2 April – Clinical Controversies
Andrew M. Nunn, MD; Jose L. Pascual, MD, PhD, FRCS(C), FACS
This article looks at the controversy surrounding death by neurological criteria.

After emerging from the intensive care unit (ICU) room on that damp Saturday evening, Dr. Johnson, the neurosurgeon, informed Mrs. Satterfield that her husband had died. His calm and empathetic tone evoked no more than a blank, emotionless expression from this new widow.  As the local organ procurement organization approached Mrs. Satterfield for donation, she could not come to grips with the fact that her 37-year-old husband of 10 years was now “dead,” yet his heart continued to beat. Just yesterday he was repairing a shingle on their roof and joking with her. This confusion, the inability to grasp the situation and the apparently contradictory information led her to decline organ donation.

Death by neurological criteria has evolved quickly since the mid-20th century.  Originally defined as the total cessation of respiration and circulation, advances in organ support technology—in particular the mechanical ventilator—made this definition inadequate.  Patients who would have previously died were now living much longer.  Successful kidney transplantation became a reality in the 1950s, and Christiaan Barnard performed the world’s first human heart transplant in 1967. With the desire to more precisely define death, the Ad Hoc Committee of the Harvard Medical School to Examine the Definition of Brain Death published its 1968 final report in JAMA, paving the way for a new way to die: brain death.(1) 

This new definition transcended many different personal and cultural views but was relatively well accepted and soon became established in the medical and legal communities.  More than a decade later, in 1981, a President’s Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research released a report, Defining Death.(2)  This landmark report officially recognized that cessation of brain activity was in and of itself an acceptable way to define death. This would eventually lead to the drafting of the Uniform Determination of Death Act, which recognized “irreversible cessation of circulatory and respiratory functions, or irreversible cessation of all functions of the entire brain, including the brain stem” as criteria for death. The Commission contended that the integrated functioning of the human body no longer existed upon cessation of brain function. This would later be challenged.

In 1995, in an attempt to standardize the medical diagnosis of brain death, the American Academy of Neurology (AAN) released a summary statement, Practice Parameters for Determining Brain Death in Adults.(3) This statement defined brain death as “the absence of clinical brain function when the proximate cause is known and demonstrably irreversible.” According to AAN, the diagnosis first requires exclusion of confounding medical conditions such as intoxication, hypothermia or other metabolic disturbances. The three necessary findings to declare brain death are coma/unresponsiveness, absence of brainstem reflexes and apnea. Optional confirmatory testing, including angiography, electroencephalography, transcranial Doppler ultrasonography, technetium-99m brain scan, and somatosensory evoked potentials, are only indicated when the clinical examination either cannot be performed or evaluated adequately. In a 2010 update, AAN further attempted to standardize the diagnosis of brain death by stressing an observation period to ensure permanent cessation of brain activity, the observation of complex motor movements that may confuse the determination of brain death, the safety of techniques of the apnea test, and the evidence to support the ancillary tests.(4) The authors were quick to highlight the fact that there is no report of any adult ever recovering brain function after brain death was diagnosed by the AAN criteria. The authors also highlight the lack of evidence for determination of brain death in the guideline supplement, Practical (Non-Evidence-Based) Guidance for Determination of Brain Death.(5) Here the process is broken down into four clear steps: clinical evaluation (prerequisites), clinical evaluation (neurological assessment), ancillary tests, and documentation, with few “new” recommendations added to the 1995 report.

Although these initial reports were relatively well accepted and received, the medical community and the public began to question the idea of “brain death” more and more as time elapsed. This is in stark contrast to most advances in medicine where initial skepticism evolves into universal acceptance as the evidence grows. Very little supportive evidence informed all of the summary statements and recommendations made about brain death; the conversation was as much opinion as it was science.  Indeed, this was an ethical and philosophical question that desperately needed an answer. And the question itself began to change from “what is death?” to “what is life?”

The uneasiness and desire to find answers eventually prompted the President’s Council on Bioethics to release Controversies in the Determination of Death.(6) The concept of “brain death” was replaced by “total brain failure.” Through philosophical and ethical discussions, the Council clarified that integrated function (wound healing, maintenance of temperature, fighting infections) may continue to exist, but that those functions do not constitute wholeness. Death by neurologic criteria was redefined as the loss of the “vital work” of the living organism after “total brain failure.” Work was defined as self-preservation and interactions with one’s surroundings, satisfied by the organism’s ability to receive stimuli from their surroundings, ability to act upon the work to obtain what is needed and to have the “basic felt need” to pursue one’s needs. Without these elements, the organism no longer “works” and is thus dead. 

There are many flaws with this theory as well. Miller and Truog, in their commentary on the Council’s report, argue that loss of vital work would then declare a patient in a persistent vegetative state dead.(7) How can the two be distinguished from one another? In essence, they submit that there has been no “coherent account” as to why patients with “total brain failure” are dead. 

Although no explanation of death by neurological criteria is flawless, we submit that there is indeed an explanation and defense that is plausible. When a human suffers from irreversible loss of consciousness and is unable to interact with the environment and is unable to sustain life without artificial external support, then that person is no longer living and ceases to exist as a person. The task at hand is not to define death, but instead to define life, which is well articulated in the Council’s definition of “vital work.” (6) After defining life, the definition of death becomes clear; it’s simply the time at which life no longer exists. This debate is polarizing, in many ways similar to the debate on the ethics and morals as they relate to abortion at the other end of the spectrum of life. As it stands today, when life ceases to exist, whether by cessation of respiration or circulation or by “total brain failure,” death has occurred.

Practitioners must be familiar with death by neurological criteria as well as prepared to explain it to patients’ families in lay terms. The idea of declaring a person “dead” who still has a heartbeat is incomprehensible to many and an explanation from the practitioner can help families interpret this concept. Statutes for declaration of death by neurological criteria vary slightly from state to state, but tremendous variation in practice continues to exist.8 Nonetheless, it is essential to standardize this process as much as possible prior to approaching families. Standardization not only minimizes the confusion surrounding brain death but also allows families to better understand and grasp this difficult and complex separation of life and death. 


1. A definition of irreversible coma. Report of the  Ad Hoc Committee of the Harvard Medical School to Examine the Definition of Brain Death. JAMA. 1968 Aug 5;205(6):337-340.
2. President’s Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research. Defining Death: A Report on the Medical, Legal and Ethical Issues in the Determination of Death. Washington, DC: Government Printing Office; 1981.
3. Practice parameters for determining brain death in adults (summary statement). The Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 1995 May;45(5):1012-1014.
4. Wijdicks EF, Varelas PN, Gronseth GS, Greer DM; American Academy of Neurology. Evidence-based guideline update: determining brain death in adults: Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2010 Jun 8;74(23):1911-1918.
5. American Academy of Neurology clinician guideline supplement: practical (non-evidence-based) guidance for determination of brain death. 2010.  Available at: Accessed April 3, 2015.
6. President's Council on Bioethics. Controversies in the Determination of Death: A White Paper by the President's Council on Bioethics. Washington, DC. December 2008.  Available at Accessed January 16, 2015.
7. Miller FG, Truog RD. The incoherence of determining death by neurological criteria: a commentary on "Controversies in the Determination of Death," a White Paper by the President's Council on Bioethics. Kennedy Inst Ethics J. 2009 Jun;19(2):185-193.
8. Da Silva IR, Frontera JA. Worldwide barriers to organ donation. JAMA Neurol. 2015 Jan 1;72(1):112-118.