The Neuroethics of Disorders of Consciousness

A Brief History of Evolving Ideas

Michael J. Young; Yelena G. Bodien; Joseph T. Giacino; Joseph J. Fins; Robert D. Truog; Leigh R. Hochberg; Brian L. Edlow

Disclosures

Brain. 2021;144(11):3291-3310. 

In This Article

Abstract and Introduction

Abstract

Neuroethical questions raised by recent advances in the diagnosis and treatment of disorders of consciousness are rapidly expanding, increasingly relevant and yet underexplored. The aim of this thematic review is to provide a clinically applicable framework for understanding the current taxonomy of disorders of consciousness and to propose an approach to identifying and critically evaluating actionable neuroethical issues that are frequently encountered in research and clinical care for this vulnerable population. Increased awareness of these issues and clarity about opportunities for optimizing ethically responsible care in this domain are especially timely given recent surges in critically ill patients with prolonged disorders of consciousness associated with coronavirus disease 2019 around the world.

We begin with an overview of the field of neuroethics: what it is, its history and evolution in the context of biomedical ethics at large. We then explore nomenclature used in disorders of consciousness, covering categories proposed by the American Academy of Neurology, the American Congress of Rehabilitation Medicine and the National Institute on Disability, Independent Living and Rehabilitation Research, including definitions of terms such as coma, the vegetative state, unresponsive wakefulness syndrome, minimally conscious state, covert consciousness and the confusional state.

We discuss why these definitions matter, and why there has been such evolution in this nosology over the years, from Jennett and Plum in 1972 to the Multi-Society Task Force in 1994, the Aspen Working Group in 2002 and the 2018 American and 2020 European Disorders of Consciousness guidelines. We then move to a discussion of clinical aspects of disorders of consciousness, the natural history of recovery and ethical issues that arise within the context of caring for people with disorders of consciousness.

We conclude with a discussion of key challenges associated with assessing residual consciousness in disorders of consciousness, potential solutions and future directions, including integration of crucial disability rights perspectives.

Introduction

Neuroethical questions raised by recent advances in the diagnosis and treatment of disorders of consciousness (DoC) are rapidly expanding, increasingly relevant and yet underexplored. The aim of this thematic review is to provide a clinically applicable framework for understanding the current taxonomy of DoC and to propose an approach to identifying and critically evaluating actionable neuroethical issues that are frequently encountered in research and clinical care for this vulnerable population. Increased awareness of these issues and clarity about opportunities for optimizing ethically-responsible care in this domain is especially timely given recent surges in critically ill patients with prolonged DoC associated with coronavirus disease 2019 (COVID-19) around the world.[1–3]

Contemporary debates at the crossroads of the neurology and ethics of consciousness have been presaged by centuries of neuroscientific and philosophical inquiry relating to the content and boundaries of consciousness. Questions such as how something as phenomenologically rich as consciousness emerges from our neural repertoire are at the core of efforts to understand what matters most in the human experience. While these two streams of investigation, the neuroscientific and the philosophical, have proceeded largely in isolation from each other, their ultimate epistemic aims are shared, and impactful insights stand to be gained by examining how key findings of each field may meaningfully inform the other.[4] Integration of philosophical and neuroscientific insights is especially critical as conceptual questions and ethical dilemmas have become increasingly commonplace and consequential in clinical practice and research.

In clinical neurology, concepts surrounding consciousness have been defined and operationalized in a way that forms a separate yet complimentary matrix for thinking about the difficult problems that philosophers have been grappling with for ages. Especially in their role as consultants, neurologists are routinely called upon to assess patients' levels of consciousness, to predict outcomes when consciousness is lost or diminished, to identify opportunities for fostering neurorecovery and to counsel families on what they might expect and how to prepare optimally for possible outcomes. In turn, these assessments and recommendations form the dominant axis around which weighty decisions are made regarding the intensity and duration of care that ought to be offered. Assessments of degrees of consciousness and capacities for recovery figure prominently in decisions to limit or continue life-sustaining treatment, speaking powerfully to the centrality of consciousness to the concept of personhood and to what makes life worth living.[5–7] The prolonged utilization of limited intensive or supportive care resources for patients perceived to have no capacity for additional neurological recovery can also cause moral distress among healthcare providers.[8–10] Viewed in this way, the ethical importance of having clarity on how to approach decisions about life-sustaining therapy becomes imminently apparent. Our discussion here will be especially germane of an incisive formulation of neurology and its ultimate aims by Wilder Penfield, which was affixed to the wall of the Montreal Neurological Institute after his death as a homage to his legacy. Penfield remarked that the 'central aim of neurology is to understand man himself'. In designing the ceiling of the Montreal Neurological Institute entrance hall, Penfield chose to feature the aphorism of Galen that 'I have seen the injured brain healed,' a memorialization that refuted the nihilistic Hippocratic view of brain injury and contextualized the vision of a new era in clinical neuroscience and neurotherapeutics.[11,12] Understanding consciousness, its ethical dimensions and philosophical implications, is at the centre of this enterprise.

We begin with an overview of the field of neuroethics. We then explore nomenclature used in DoC, covering categories proposed by the American Academy of Neurology (AAN), the American Congress of Rehabilitation Medicine (ACRM) and the National Institute on Disability, Independent Living and Rehabilitation Research (NIDILRR), including definitions of terms such as coma, the vegetative state, unresponsive wakefulness syndrome, minimally conscious state (MCS) and post-traumatic confusional state (PTCS). We discuss why these definitions matter and why there has been such evolution in this nosology over the years, from Jennett and Plum in 1972 to the Multi-Society Task Force in 1994, the Aspen Working Group in 2002 and the 2018 American and 2020 European DoC guidelines. We then move to a discussion of clinical aspects of DoC, the natural history of recovery and ethical issues that arise within the context of caring for persons with DoC. We conclude with a discussion of key challenges associated with assessing residual awareness in DoC, potential solutions and future directions, including integration of crucial disability rights perspectives.

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