Disorders of consciousness after acquired brain injury: the state of the science

Abstract

| The concept of consciousness continues to defy definition and elude the grasp of philosophical and scientific efforts to formulate a testable construct that maps to human experience. Severe acquired brain injury results in the dissolution of consciousness, providing a natural model from which key insights about consciousness may be drawn. In the clinical setting, neurologists and neurorehabilitation specialists are called on to discern the level of consciousness in patients who are unable to communicate through word or gesture, and to project outcomes and recommend approaches to treatment. Standards of care are not available to guide clinical decision-making for this population, often leading to inconsistent, inaccurate and inappropriate care. In this Review, we describe the state of the science with regard to clinical management of patients with prolonged disorders of consciousness. We review consciousness-altering pathophysiological mechanisms, specific clinical syndromes, and novel diagnostic and prognostic applications of advanced neuroimaging and electrophysiological procedures. We conclude with a provocative discussion of bioethical and medicolegal issues that are unique to this population and have a profound impact on care, as well as raising questions of broad societal interest.

Divergent neural responses to narrative speech in disorders of consciousness

“…Patients with chronic disorders of consciousness (DOC) have varied outcomes that are difficult to prognosticate 1, 2. Accurate assessment of higher level cognitive abilities such as auditory attention is essential for accurate diagnosis and may determine candidacy for assistive communication devices.…”

Assessment and Intervention with Patients with Severe Disorders of Consciousness

“…Notwithstanding the power of these techniques, their application remains a difficult methodological and practical challenge in most medical and care or rehabilitation contexts and might also lead to unreliable results in patients who have problems focusing on specific assessment stimuli or following verbal instructions (Bodien and Giacino 2016;Edlow et al 2013;Harrison and Connolly 2013;Mashour and Avidan 2013;Vul and Pashler 2012). A similarly powerful and complex alternative to fMRI in this assessment area is positron emission tomography (PET) (Giacino et al 2014;Rosanova et al 2012;Stender et al 2014Stender et al , 2016.…”

“…Much attention has been devoted to assessment and intervention with patients with disorders of consciousness (i.e., patients whose consciousness is affected by damage to the brain) (Bodien and Giacino 2016;Giacino et al 2014;Gosseries et al 2016;Laureys et al 2006;Lopez-Rolon 2017;Stokes et al 2016). Regarding assessment, the main viewpoint in recent literature underlines the importance of reliably determining the patients' state of functioning (whether they are in a vegetative state or in a minimally conscious state) and suggests a variety of assessment tools that might be suitable for that purpose (Demertzi et al 2015;Fingelkurts et al 2016;Fins 2016;Lancioni et al 2014a).…”

Unresponsive, but Aware: The Non-Behavioral Minimally Conscious State

“…Some of these suffer from prolonged disorders of consciousness, such as the minimally conscious state (MCS), or the unresponsive wakefulness syndrome (UWS). Patients in UWS retain arousal, but show no awareness of themselves or surroundings, whereas patients in MCS show fluctuating but reproducible behavioral signs of consciousness [1]. Long-term recovery of consciousness from UWS is uncertain, but progression into MCS is an important indicator of better prognosis.…”