Clinical case: An older male adult with prolonged cardiac arrest was managed with targeted temperature management (TTM) to reduce potential brain injury. Once he was taken off TTM, the patient remained in an unresponsive coma for 48 hours and needed assessment for brain death. In such cases, accurate determination of brain death using neurologic criteria allows for appropriate medical decision-making, including the potential for organ donation and cessation of life support.
Brain Death/Death by Neurologic Criteria (BD/DNC) refers to the complete and irreversible cessation of brain function based on key diagnostic features and in-depth evaluation. Though the term “brain death” is used colloquially, medical providers often use “death by neurologic criteria” to formally describe cessation of brain function. Both terms are used interchangeably in clinical practice.
Alex Rae-Grant MD, FRCPC, FAAN, Executive Editor at DynaMed, collaborated with experts to develop the 2023 publication of the American Academy of Neurology (AAN) consensus guideline on pediatric and adult BD/DNC. This guideline, with eighty-five detailed recommendations, provides the most current and comprehensive consensus on the criteria needed to confirm BD/DNC in adults and children.
We recently interviewed Dr. Rae-Grant to learn more about the BD/DNC guideline and update process.
How did you become involved in developing the BD/DNC guideline?
I was the chairperson of the AAN guideline subcommittee for years. The revision of the BD/DNC criteria was requested as it had been last revised in 2010. I was one of the facilitators, which included working with staff, organization leaders, and the guideline panel to make the update happen.
What was the process for creating the guideline? How long did it take to complete?
Creating the guideline started with me and other facilitators meeting with guideline development leaders, then recruiting a panel of experts. The panel initially met to discuss what recommendations to include and vote on. After that, there were numerous meetings of the panel and leadership to discuss recommendations.
We worked with several professional societies to co-develop the guideline, including the American Academy of Pediatrics, American College of Radiology, Congress of Neurological Surgeons, Society of Critical Care Medicine, and Neurocritical Care Society.
Overall, the process took more than four and a half years.
What was the ideal outcome, and what was challenging during guideline development?
We aimed to have a single document to represent care for any person and any unusual circumstances during the evaluation of BD/DNC. This was challenging as the previous AAN guideline was only for adults, and a separate guideline from the AAP was for children. The updated guideline includes evaluation recommendations for adults, children, people who are pregnant, and those who are on extra corporeal membrane circulation (ECMO).
Though individuals had their own idea of what the guideline should look like, it didn’t necessarily result as they envisioned. That’s usually a good sign of compromise.
What are the key messages for current practice?
The BD/DNC evaluation itself has not changed dramatically. With the guideline we sought to clearly state the criteria so the clinician gets them correct. Prior studies have shown variation in practice in brain death determination, so this guideline was timely.
For a BD/DNC declaration, the exam must demonstrate no measurable brain function. This includes documenting that the patient is not breathing spontaneously, shows no cranial nerve response, and does not respond to painful stimuli. Confounders such as certain medications, very low body temperature or severe metabolic derangements need to be ruled out before doing this evaluation.
The AAN released an evaluation tool with the updated guideline that includes consideration of specific patient details. For example, there are different criteria for children in terms of how long to wait before evaluation and how many different exams are required. There are also considerations such as hypoxia or if anything occurred with medication.
Were there any key changes to current practice?
Along with clarifying the evaluation in certain patient populations (such as those who are pregnant), we added guidance for unusual circumstances (such as patients with posterior fossa primary injury or those in the intensive care unit on membrane oxygenation).
We also clarify guidance on testing, which may be needed to support or rule out the BD/DNC diagnosis. For example, we recommend against electroencephalogram (EEG) as it does not evaluate brainstem function directly, a key component in BD/DNC evaluation. Evoked potentials were not recommended either as they interrogate some brain functions while missing others. In current practice, there are tests that supersede EEG to confirm the diagnosis.
Additionally, we discussed the number of exams required for diagnosis. The prior recommendation in adults was to perform one neurological exam and an apnea test, but some panelists believed that a second exam was necessary. Although not strongly supported in the literature, we decided that a second exam may be helpful under certain circumstances. Ultimately the second exam was included as a weak recommendation for clinicians to consider.
Back to the Case: The family consented to an evaluation for BD/DNC. Following a detailed neurological evaluation, a pupillary reflex to bright light confirmed the presence of some brainstem activity, and an apnea test revealed evidence of spontaneous respiratory effort. With these findings, the patient did not meet criteria for a BD/DNC diagnosis. Clinicians kept the patient for observation and evaluation with the Glasgow Coma Scale. After another 24 hours, the patient became more alert and was further evaluated for neurological injury. Neurological outcomes vary in such patients, ranging from full recovery to major disability.
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We appreciate hearing from Dr. Rae-Grant about some of the intricacies involved in developing consensus recommendations for BD/DNC.
