The Neurology of Death and the Dying Brain: A Pictorial Essay

Abstract

As neurologists earn their living with the preservation and restoration of brain function, they are also well-positioned to address the science behind the transition from life to death. This essay in pictures highlights areas of neurological expertise needed for brain death determination; shows pitfalls to avoid during the clinical examination and interpretation of confirmatory laboratory tests in brain death protocols; illustrates the great variability of brain death legislations around the world; discusses arguments for the implementation of donation after circulatory death (DCD); points to unresolved questions related to DCD and the time between cardiac standstill and organ procurement ("hands-off period"); provides an overview of the epidemiology and semiology of near-death experiences, including their importance for religion, literature, and the visual arts; suggests biological mechanisms for near-death experiences such as dysfunction of temporoparietal cortex, N-methyl-D-aspartate receptor antagonism, migraine aura, and rapid eye movement sleep; hypothesizes that thanatosis (aka. death-feigning, a common behavioral trait in the animal kingdom) represents the evolutionary origin of neardeath experiences; and speculates about the future implications of recent attempts of brain resuscitation in an animal model. The aim is to provide the reader with a thorough understanding that the boundaries within the neurology of death and the dying brain are being pushed just like everywhere else in the clinical neurosciences.

The evolutionary origin of near-death experiences: a systematic investigation

“… 86 One of us therefore recently suggested that terminal CSDs are a phylogenetically preserved mechanism which must have occurred in the last common ancestor of humans and insects for over 500 million years ago. 14 CSDs might therefore be conceivable as an underlying mechanism for both NDE and thanatosis. Indeed, migraine aura (which is caused by CSDs) was a predictor of NDE in a crowdsourcing study 13 of unprimed lay people adjusted for age and sex (OR 2.33, P < 0.001).…”

“…The evidence from all these candidate mechanisms has been combined into a ‘diathesis-stress model’. 11 , 14 , 101 Thus, an unusually sensitive arousal system (i.e. the diathesis), as revealed by REM sleep intrusion, would predispose people to NDE in life-threatening situations and emotional stress.…”

“…If this would be the case, then comparative biology might allow insights into the origins of NDEs. 14–16 …”

“… 25 , 26 Thus, thanatosis is an anti-predator strategy that is part of an innate defense cascade, 27 , 28 which is activated when fight or flight are no longer possible. 14 , 29 , 30 It involves sudden onset of immobility, with or without loss of tonic muscular activity, and unresponsiveness to external stimuli but preserved awareness. 30 Of note, this is akin to some forms of REM sleep intrusion into wakefulness in humans, e.g.…”

Eye-opening in brain death: A case report and review of the literature

“…Brain death is defined as the complete and permanent absence of all brain functions ( Busl and Greer, 2009 ). Protocols for ascertaining brain death vary widely from country to country ( Kondziella, 2020 ). In Italy, a patient is considered brain dead when he is in a coma, showing apnoea under particular clinical parameters, and having no brain stem reflexes ( Legge, 1993 , Decreto Ministero della Salute 11 Aprile 2008 ).…”