Wijdicks and colleagues1 recently presented the Full Outline of UnResponsiveness (FOUR) scale as an alternative to the Glasgow Coma Scale (GCS)2 in the evaluation of consciousness in severely brain-damaged patients. They studied 120 patients in an intensive care setting (mainly neuro-intensive care) and claimed that “the FOUR score detects a locked-in syndrome, as well as the presence of a vegetative state.”1 We fully agree that the FOUR is advantageous in identifying locked-in patients given that it specifically tests for eye movements (...) or blinking on command. This is welcomed given that misdiagnosis of the locked-in syndrome has been shown to occur in more than half of the cases (see Laureys and colleagues3 for review). As for the diagnosis of the vegetative state, the scale explicitly tests for visual pursuit, and hence can disentangle the vegetative state from the minimally conscious state (MCS). The diagnostic criteria for MCS have been proposed4 only recently, but Wijdicks and colleagues1 do not mention the existence of this clinical entity in their article. As for the vegetative state, MCS can be encountered in the acute or subacute setting as a transitional state on the way to further recovery, or it can be a more chronic or even permanent condition. The MCS refers to patients showing inconsistent, albeit clearly discernible, minimal behavioral evidence of consciousness (eg, localization of noxious stimuli, eye fixation or tracking, reproducible movement to command, or nonfunctional verbalization).4 The FOUR scale does not test for all of the behavioral criteria required to diagnose MCS.4 It is known from the literature (see Majerus and colleagues5 for review) that about a third of patients diagnosed with vegetative state are actually in MCS, and this misdiagnosis can lead to major clinical, therapeutic, and ethical consequences. We tested the ability of the newly proposed FOUR scale to correctly diagnose the vegetative state in an acute (intensive care and neurology ward) and chronic (neurorehabilitation) setting.. (shrink)
Niedenthal et al. discuss the importance of eye gaze in embodied simulation and, more globally, in the processing of emotional visual stimulation (such as facial expression). In this commentary, we illustrate the relationship between oriented eye movements, consciousness, and emotion by using the case of severely brain-injured patients recovering from coma (i.e., vegetative and minimally conscious patients).
Some patients awaken from their coma but only show reflex motor activity. This condition of wakeful (eyes open) unawareness is called the vegetative state. In 2002, a new clinical entity coined ‘‘minimally conscious state’’ defined patients who show more than reflex responsiveness but remain unable to communicate their thoughts and feelings. Emergence from the minimally conscious state is defined by functional recovery of verbal or nonverbal communication.1 Our empirical medical definitions aim to propose clearcut borders separating disorders of consciousness such (...) as coma, vegetative state and minimally conscious state but clinical reality shows that these boundaries can often be fuzzy (fig 1). Recent clinical, electrophysiological and neuroimaging studies are shedding light on these challenging limits of consciousness encountered following severe acute brain damage. At the patient’s bedside, it is very challenging to differentiate reflex or automatic motor behaviour from movements indicating signs of consciousness, and hence some minimally conscious patients might be misdiagnosed as being vegetative. For some motor responses (eg, blinking to visual threat, brief fixation, normal flexion response to pain, etc) it remains unclear whether they truly are voluntary or willed because we lack convincing scientific evidence. We also lack consensus on how to practically assess some of these behavioural responses. For example, there is no agreement on what stimulus to employ in the assessment of visual pursuit movements— often one of the first clinical signs heralding the transition from the vegetative to the minimally conscious state. Vanhaudenhuyse and colleagues2 recently studied visual pursuit in 51 post-comatose patients comparing eye tracking of a moving object, person or mirror. It was shown that more.. (shrink)
BackgroundWith the emergence of Brain Computer Interfaces, clinicians have been facing a new group of patients with severe acquired brain injury who are unable to show any behavioral sign of consciousness but respond to active neuroimaging or electrophysiological paradigms. However, even though well documented, there is still no consensus regarding the nomenclature for this clinical entity.ObjectivesThis systematic review aims to 1) identify the terms used to indicate the presence of this entity through the years, and 2) promote an informed discussion (...) regarding the rationale for these names and the best candidates to name this fascinating disorder.MethodsThe Disorders of Consciousness Special Interest Group of the International Brain Injury Association launched a search on Pubmed and Google scholar following PRISMA guidelines to collect peer-reviewed articles and reviews on human adults published in English between 2006 and 2021.ResultsThe search launched in January 2021 identified 4,089 potentially relevant titles. After screening, 1,126 abstracts were found relevant. Finally, 161 manuscripts were included in our analyses. Only 58% of the manuscripts used a specific name to discuss this clinical entity, among which 32% used several names interchangeably throughout the text. We found 25 different names given to this entity. The five following names were the ones the most frequently used: covert awareness, cognitive motor dissociation, functional locked-in, non-behavioral MCS and higher-order cortex motor dissociation.ConclusionSince 2006, there has been no agreement regarding the taxonomy to use for unresponsive patients who are able to respond to active neuroimaging or electrophysiological paradigms. Developing a standard taxonomy is an important goal for future research studies and clinical translation. We recommend a Delphi study in order to build such a consensus. (shrink)