Detecting Awareness in the Vegetative State
ABSTRACT We used functional magnetic resonance imaging to demonstrate preserved conscious awareness in a patient fulfilling the criteria
for a diagnosis of vegetative state. When asked to imagine playing tennis or moving around her home, the patient activated
predicted cortical areas in a manner indistinguishable from that of healthy volunteers.
Full-textDOI: · Available from: Melanie Boly, Dec 28, 2013
- SourceAvailable from: Sofia Moratti
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- "While experimental research along the lines of Monti et al. (2010a) grapples with these questions, it seems equally urgent to gather statistical data by means of large-scale, multi-center, longitudinal studies, on the variables affecting the patients' likelihood of recovering consciousness and at least part of their motor functioning. Some such variables are already known, the patient's age, for example (Owen et al. 2006). Brain imaging may have a very important role to play in this kind of inquiry, leading to more information on the relations between the type and location of brain lesions, and long-term recovery outcome (Fins 2003; Coleman et al. 2009). "
DESCRIPTION: Recently, a number of neuroimaging studies have been conducted, aimed at detecting signs of consciousness in patients with a diagnosis of vegetative or minimally conscious state. The contributions appeared during an ongoing international ethical and socio-legal debate, on the admissibility of decisions to withdraw artificial nutrition from vegetative patients, thereby allowing them to die. We argue that neuroimaging is more likely to contribute to medical diagnosis and decision making if two requirements are met. First, those studies inferred awareness from the neural correlates of cognitive processes that are assumed to involve consciousness. However, neural correlates of consciousness proper, as defined by current philosophy and neuroscience, are the only admissible non-behavioral signs of awareness. Second, in those studies patients attempted to answer medically irrelevant questions by modulating their cortical activity in imagery tasks. We suggest patients should instead be queried on matters relevant to their clinical condition and quality of life.
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- "Functional magnetic resonance imaging (fMRI) studies by Owen et al. (2006) and others Boly et al. (2007), Monti et al. (2010), demonstrating detection of awareness in the unresponsive wakefulness syndrome (UWS, Laureys et al., 2010), paved the way for the development of brain–computer interfaces (BCI) as a means of communication in this patient group. In these studies, patients were asked to imagine playing tennis, or to navigate through their own apartment. "
ABSTRACT: Further development of an EEG based communication device for patients with disorders of consciousness (DoC) could benefit from addressing the following gaps in knowledge – first, an evaluation of different types of motor imagery; second, an evaluation of passive feet movement as a mean of an initial classifier setup; and third, rapid delivery of biased feedback. To that end we investigated whether complex and / or familiar mental imagery, passive, and attempted feet movement can be reliably detected in patients with DoC using EEG recordings, aiming to provide them with a means of communication. Six patients in a minimally conscious state (MCS) took part in this study. The patients were verbally instructed to perform different mental imagery tasks (sport, navigation), as well as attempted feet movements, to induce distinctive event-related (de)synchronization (ERD/S) patterns in the EEG. Offline classification accuracies above chance level were reached in all three tasks (i.e. attempted feet, sport, and navigation), with motor tasks yielding significant (p<0.05) results more often than navigation (sport: 10 out of 18 sessions; attempted feet: 7 out of 14 sessions; navigation: 4 out of 12 sessions). The passive feet movements, evaluated in one patient, yielded mixed results: whereas time-frequency analysis revealed task-related EEG changes over neurophysiological plausible cortical areas, the classification results were not significant enough (p<0.05) to setup an initial classifier for the detection of attempted movements. Concluding, the results presented in this study are consistent with the current state of the art in similar studies, to which we contributed by comparing different types of mental tasks, notably complex motor imagery and attempted feet movements, within patients. Furthermore, we explored new venues, such as an evaluation of passive feet movement as a mean of an initial classifier setup, and rapid delivery of biased feedback.Frontiers in Human Neuroscience 12/2014; 8:1009. DOI:10.3389/fnhum.2014.01009 · 2.90 Impact Factor
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- "Recent functional neuroimaging studies based on mental imagery tasks provided evidence for awareness in patients diagnosed with UWS/VS or MCS as they presented with volitional control of brain functions detected with electroencephalography (Schnakers et al., 2008b; Cruse et al., 2011; Goldfine et al., 2011) or functional magnetic resonance imaging (Owen et al., 2006; Boly et al., 2007; Monti et al., 2010; Bardin et al., 2011). Additionally, electromyography (Bekinschtein et al., 2008) or pupil dilation (Stoll et al., 2013) monitoring can offer alternative ways to identify response to command in DOC. "
ABSTRACT: Detecting signs of consciousness in patients in a vegetative state/unresponsive wakefulness syndrome (UWS/VS) or minimally conscious state (MCS) is known to be very challenging. Plotkin et al. (2010) recently showed the possibility of using a breathing-controlled communication device in patients with locked in syndrome. We here aim to test a breathing-based "sniff controller" that could be used as an alternative diagnostic tool to evaluate response to command in severely brain damaged patients with chronic disorders of consciousness (DOC). Twenty-five DOC patients were included. Patients' resting breathing-amplitude was measured during a 5 min resting condition. Next, they were instructed to end the presentation of a music sequence by sniffing vigorously. An automated detection of changes in breathing amplitude (i.e., >1.5 SD of resting) ended the music and hence provided positive feedback to the patient. None of the 11 UWS/VS patients showed a sniff-based response to command. One out of 14 patients with MCS was able to willfully modulate his breathing pattern to answer the command on 16/19 trials (accuracy 84%). Interestingly, this patient failed to show any other motor response to command. We here illustrate the possible interest of using breathing-dependent response to command in the detection of residual cognition in patients with DOC after severe brain injury.Frontiers in Human Neuroscience 12/2014; 8:1020. DOI:10.3389/fnhum.2014.01020 · 2.90 Impact Factor