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Lechinger J, Chwala-Schlegel N, Fellinger R, Donis J, Michitsch G, Pichler G, Schabus M. Mirroring of a simple motor behavior in Disorders of Consciousness. Clin Neurophysiol 2013; 124:27-34. [PMID: 22721652 DOI: 10.1016/j.clinph.2012.05.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 05/21/2012] [Accepted: 05/22/2012] [Indexed: 10/28/2022]
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153
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Gantner IS, Bodart O, Laureys S, Demertzi A. Our rapidly changing understanding of acute and chronic disorders of consciousness: challenges for neurologists. FUTURE NEUROLOGY 2013. [DOI: 10.2217/fnl.12.77] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A number of recent studies suggest that some ‘vegetative state’ patients have been misdiagnosed, judging by their ability to follow commands and in some cases even communicate through brain activity. Such studies highlight the difficulty in forming a diagnosis based only on behavioral assessments. We think that neuroimaging and electrophysiology methods will be used more frequently in clinical settings, integrated with existing behavioral assessments. Such efforts are expected to lead to a more accurate understanding of individual patients’ cognitive abilities or even provide prognostic indicators. In terms of treatment planning (i.e., pain management and end-of-life decision-making), patients with disorders of consciousness are now offered the possibility of expressing their preferences by means of brain–computer interfaces. What remains to be clarified is the degree to which such indirect responses can be considered reliable and of legal representation.
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Affiliation(s)
- Ithabi S Gantner
- Coma Science Group, Cyclotron Research Center & CHU Neurology Department, University of Liège, Allée du 6 Août no 8, Sart Tilman B30, 4000 Liège, Belgium
| | - Olivier Bodart
- Coma Science Group, Cyclotron Research Center & CHU Neurology Department, University of Liège, Allée du 6 Août no 8, Sart Tilman B30, 4000 Liège, Belgium
| | - Steven Laureys
- Coma Science Group, Cyclotron Research Center & CHU Neurology Department, University of Liège, Allée du 6 Août no 8, Sart Tilman B30, 4000 Liège, Belgium
| | - Athena Demertzi
- Coma Science Group, Cyclotron Research Center & CHU Neurology Department, University of Liège, Allée du 6 Août no 8, Sart Tilman B30, 4000 Liège, Belgium
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154
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Cruse D, Chennu S, Fernández-Espejo D, Payne WL, Young GB, Owen AM. Detecting awareness in the vegetative state: electroencephalographic evidence for attempted movements to command. PLoS One 2012; 7:e49933. [PMID: 23185489 PMCID: PMC3503880 DOI: 10.1371/journal.pone.0049933] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 10/18/2012] [Indexed: 12/02/2022] Open
Abstract
Patients in the Vegetative State (VS) do not produce overt motor behavior to command and are therefore considered to be unaware of themselves and of their environments. However, we recently showed that high-density electroencephalography (EEG) can be used to detect covert command-following in some VS patients. Due to its portability and inexpensiveness, EEG assessments of awareness have the potential to contribute to a standard clinical protocol, thus improving diagnostic accuracy. However, this technique requires refinement and optimization if it is to be used widely as a clinical tool. We asked a patient who had been repeatedly diagnosed as VS for 12-years to try to move his left and right hands, between periods of rest, while EEG was recorded from four scalp electrodes. We identified appropriate and statistically reliable modulations of sensorimotor beta rhythms following commands to try to move, which could be significantly classified at a single-trial level. These reliable effects indicate that the patient attempted to follow the commands, and was therefore aware, but was unable to execute an overtly discernable action. The cognitive demands of this novel task are lower than those used previously and, crucially, allow for awareness to be determined on the basis of a 20-minute EEG recording made with only four electrodes. This approach makes EEG assessments of awareness clinically viable, and therefore has potential for inclusion in a standard assessment of awareness in the VS.
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Affiliation(s)
- Damian Cruse
- Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada.
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155
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Höller Y, Bergmann J, Kronbichler M, Crone JS, Schmid EV, Thomschewski A, Butz K, Schütze V, Höller P, Trinka E. Real movement vs. motor imagery in healthy subjects. Int J Psychophysiol 2012; 87:35-41. [PMID: 23123181 DOI: 10.1016/j.ijpsycho.2012.10.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 09/30/2012] [Accepted: 10/24/2012] [Indexed: 10/27/2022]
Abstract
Motor imagery tasks are well established procedures in brain computer interfaces, but are also used in the assessment of patients with disorders of consciousness. For testing awareness in unresponsive patients it is necessary to know the natural variance of brain responses to motor imagery in healthy subjects. We examined 22 healthy subjects using EEG in three conditions: movement of both hands, imagery of the same movement, and an instruction to hold both hands still. Single-subject non-parametric statistics were applied to the fast-Fourier transformed data. Most effects were found in the α- and β-frequency ranges over central electrodes, that is, in the μ-rhythm. We found significant power changes in 18 subjects during movement and in 11 subjects during motor imagery. In 8 subjects these changes were consistent over both conditions. The significant power changes during movement were a decrease of μ-rhythm. There were 2 subjects with an increase and 9 subjects with a decrease of μ-rhythm during imagery. α and β are the most responsive frequency ranges, but there is a minor number of subjects who show a synchronization instead of the more common desynchronization during motor imagery. A (de)synchronization of μ-rhythm can be considered to be a normal response.
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Affiliation(s)
- Yvonne Höller
- Department of Neurology, Christian-Doppler-Klinik, Paracelsus Medical University, Salzburg, Austria.
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156
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Naci L, Monti MM, Cruse D, Kübler A, Sorger B, Goebel R, Kotchoubey B, Owen AM. Brain-computer interfaces for communication with nonresponsive patients. Ann Neurol 2012; 72:312-23. [DOI: 10.1002/ana.23656] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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157
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Liang X, Kuhlmann L, Johnston LA, Grayden DB, Vogrin S, Crossley R, Fuller K, Lourensz M, Cook MJ. Extending communication for patients with disorders of consciousness. J Neuroimaging 2012; 24:31-8. [PMID: 22928842 DOI: 10.1111/j.1552-6569.2012.00744.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 06/04/2012] [Accepted: 06/05/2012] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND AND PURPOSE The difficulty of distinguishing disorders of consciousness from certain disorders of communication leads to the possibility of false diagnosis. Our aim is to communicate with patients with disorders of consciousness through asking them to answer questions with "yes/no" by performing mental imagery tasks using functional magnetic resonance imaging (fMRI). METHODS A 1.5 T fMRI study with 5 patients and a control group is presented. Speech comprehension, mental imagery, and question-answer tests were performed. RESULTS The imagery task of mental calculation produced equally distinct activation patterns when compared to navigation and motor imagery in controls. For controls, we could infer answers to questions based on imagery activations. Two patients produced activations in similar areas to controls for certain imagery tasks, however, no activations were observed for the question-answer task. CONCLUSIONS The results from 2 patients provide independent support of similar work by others with 3 T fMRI, and demonstrate broader clinical utility for these tests at 1.5 T despite lower signal-to-noise ratio. Based on the control results, mental calculation adds a robust imagery task for use in future studies of this kind.
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Affiliation(s)
- Xingwen Liang
- NeuroEngineering Lab, Department of Electrical and Electronic Engineering, University of Melbourne, Melbourne, Victoria, Australia
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158
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Chatelle C, Chennu S, Noirhomme Q, Cruse D, Owen AM, Laureys S. Brain-computer interfacing in disorders of consciousness. Brain Inj 2012; 26:1510-22. [PMID: 22759199 DOI: 10.3109/02699052.2012.698362] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Recent neuroimaging research has strikingly demonstrated the existence of covert awareness in some patients with disorders of consciousness (DoC). These findings have highlighted the potential for the development of simple brain-computer interfaces (BCI) as a diagnosis in behaviourally unresponsive patients. OBJECTIVES This study here reviews current EEG-based BCIs that hold potential for assessing and eventually assisting patients with DoC. It highlights key areas for further development that might eventually make their application feasible in this challenging patient group. METHODS The major types of BCIs proposed in the literature are considered, namely those based on the P3 potential, sensorimotor rhythms, steady state oscillations and slow cortical potentials. In each case, a brief overview of the relevant literature is provided and then their relative merits for BCI applications in DoC are considered. RESULTS A range of BCI designs have been proposed and tested for enabling communication in fully conscious, paralysed patients. Although many of these have potential applicability for patients with DoC, they share some key challenges that need to be overcome, including limitations of stimulation modality, feedback, user training and consistency. CONCLUSION Future work will need to address the technical and practical challenges facing reliable implementation at the patient's bedside.
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Affiliation(s)
- Camille Chatelle
- Coma Science Group, Cyclotron Research Centre, University of Liège, Liège, Belgium.
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159
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Laureys S, Schiff ND. Coma and consciousness: Paradigms (re)framed by neuroimaging. Neuroimage 2012; 61:478-91. [PMID: 22227888 DOI: 10.1016/j.neuroimage.2011.12.041] [Citation(s) in RCA: 227] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 12/15/2011] [Indexed: 01/18/2023] Open
Affiliation(s)
- Steven Laureys
- Coma Science Group, Cyclotron Research Centre and Neurology Department, University and University Hospital of Liège, 4000 Liège, Belgium.
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160
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Goldfine AM, Victor JD, Conte MM, Bardin JC, Schiff ND. Bedside detection of awareness in the vegetative state. Lancet 2012; 379:1701-2; author reply 1702. [PMID: 22559892 DOI: 10.1016/s0140-6736(12)60714-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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161
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Chennu S, Bekinschtein TA. Arousal modulates auditory attention and awareness: insights from sleep, sedation, and disorders of consciousness. Front Psychol 2012; 3:65. [PMID: 22403565 PMCID: PMC3293189 DOI: 10.3389/fpsyg.2012.00065] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 02/18/2012] [Indexed: 11/13/2022] Open
Abstract
The interplay between attention and consciousness is frequently tested in altered states of consciousness, including transitions between stages of sleep and sedation, and in pathological disorders of consciousness (DoC; the vegetative and minimally conscious states; VS and MCS). One of the most widely used tasks to assess cognitive processing in this context is the auditory oddball paradigm, where an infrequent change in a sequence of sounds elicits, in awake subjects, a characteristic EEG event-related potential called the mismatch negativity, followed by the classic P300 wave. The latter is further separable into the slightly earlier, anterior P3a and the later, posterior P3b, thought to be linked to task-irrelevant "bottom-up" and task-oriented "top-down" attention, respectively. We discuss here the putative dissociations between attention and awareness in DoC, sedation and sleep, bearing in mind the recently emerging evidence from healthy volunteers and patients. These findings highlight the neurophysiological and cognitive parallels (and differences) across these three distinct variations in levels of consciousness, and inform the theoretical framework for interpreting the role of attention therein.
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Affiliation(s)
- Srivas Chennu
- Department of Clinical Neurosciences, University of CambridgeCambridge, UK
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162
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Cruse D, Chennu S, Chatelle C, Fernández-Espejo D, Bekinschtein TA, Pickard JD, Laureys S, Owen AM. Relationship between etiology and covert cognition in the minimally conscious state. Neurology 2012; 78:816-22. [PMID: 22377810 DOI: 10.1212/wnl.0b013e318249f764] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVES Functional neuroimaging has shown that the absence of externally observable signs of consciousness and cognition in severely brain-injured patients does not necessarily indicate the true absence of such abilities. However, relative to traumatic brain injury, nontraumatic injury is known to be associated with a reduced likelihood of regaining overtly measurable levels of consciousness. We investigated the relationships between etiology and both overt and covert cognitive abilities in a group of patients in the minimally conscious state (MCS). METHODS Twenty-three MCS patients (15 traumatic and 8 nontraumatic) completed a motor imagery EEG task in which they were required to imagine movements of their right-hand and toes to command. When successfully performed, these imagined movements appear as distinct sensorimotor modulations, which can be used to determine the presence of reliable command-following. The utility of this task has been demonstrated previously in a group of vegetative state patients. RESULTS Consistent and robust responses to command were observed in the EEG of 22% of the MCS patients (5 of 23). Etiology had a significant impact on the ability to successfully complete this task, with 33% of traumatic patients (5 of 15) returning positive EEG outcomes compared with none of the nontraumatic patients (0 of 8). CONCLUSIONS The overt behavioral signs of awareness (measured with the Coma Recovery Scale-Revised) exhibited by nontraumatic MCS patients appear to be an accurate reflection of their covert cognitive abilities. In contrast, one-third of a group of traumatically injured patients in the MCS possess a range of high-level cognitive faculties that are not evident from their overt behavior.
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Affiliation(s)
- D Cruse
- Centre for Brain and Mind, University of Western Ontario, London, Canada.
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163
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Goldfine AM, Schiff ND. Consciousness: its neurobiology and the major classes of impairment. Neurol Clin 2011; 29:723-37. [PMID: 22032656 DOI: 10.1016/j.ncl.2011.08.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Human consciousness requires brainstem, basal forebrain, and diencephalic areas to support generalized arousal, and functioning thalamocortical networks to respond to environmental and internal stimuli. Disconnection of these interconnected systems, typically from cardiac arrest and traumatic brain injury, can result in disorders of consciousness. Brain injuries can also result in loss of motor output out of proportion to consciousness, resulting in misdiagnoses. The authors review pathology and imaging studies and derive mechanistic models for each of these conditions. Such models may guide the development of target-based treatment algorithms to enhance recovery of consciousness in many of these patients.
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Affiliation(s)
- Andrew M Goldfine
- Department of Neurology and Neuroscience, Weill Cornell Medical College, LC 803, 1300 York Avenue, New York, NY 10065, USA.
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