Objective assessment of visual pursuit in patients with disorders of consciousness: an exploratory study
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Visual pursuit is a key marker of residual consciousness in patients with disorders of consciousness (DOC). Currently, its assessment relies on subjective clinical decisions. In this study, we explore the variability of such clinical assessments, and present an easy-to-use device composed of cameras and video processing algorithms that could help the clinician to improve the detection of visual pursuit in a clinical context. Visual pursuit was assessed by an experienced research neuropsychologist on 31 patients with DOC and on 23 healthy subjects, while the device was used to simultaneously record videos of both one eye and the mirror. These videos were then scored by three researchers: the experienced research neuropsychologist who did the clinical assessment, another experienced research neuropsychologist, and a neurologist. For each video, a consensus was decided between the three persons, and used as the gold standard of the presence or absence of visual pursuit. Almost 10% of the patients were misclassified at the bedside according to their consensus. An automatic classifier analyzed eye and mirror trajectories, and was able to identify patients and healthy subjects with visual pursuit, in total agreement with the consensus on video. In conclusion, our device can be used easily in patients with DOC while respecting the current guidelines of visual pursuit assessment. Our results suggest that our material and our classification method can identify patients with visual pursuit, as well as the three researchers based on video recordings can.
KeywordsDisorders of consciousness Minimally conscious state Behavioral assessment Visual pursuit Automatic detection
The University and University Hospital of Liège, the French Speaking Community Concerted Research Action (ARC 12/17/01), the Belgian National Funds for Scientific Research (FRS-FNRS), Human Brain Project (EU-H2020-fetflagship-hbp-sga1-ga720270), and Luminous project (EU-H2020-fetopen-ga686764), the Wallonie-Bruxelles International, the James McDonnell Foundation, Mind Science Foundation, IAP research network P7/06 of the Belgian Government (Belgian Science Policy), the European Commission, the Public Utility Foundation ‘Université Européenne du Travail’, “Fondazione Europea di Ricerca Biomedica”, the Bial Foundation. OB and CM are research fellows, CC is post-doctoral fellow, and SL is research director at FRS-FNRS.
Compliance with ethical standards
Conflicts of interest
Phasya S.A. provided the device without any financial compensation.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study, or by patient surrogate-decision makers.
- 21.Hoyoux T, Wannez S, Langohr T, Wertz J, Laureys S, Verly J (2016) A new computer vision-based system to help clinicians objectively assess visual pursuit with the moving mirror stimulus for the diagnosis of minimally conscious state. In: IEEE Winter Conference on Applications of Computer Vision (WACV 2016)Google Scholar
- 22.Collobert R, Kavukcuoglu K, Farabet C (2011) Torch7: A matlab-like environment for machine learning. NIPS Work, BigLearn, pp 1–6Google Scholar
- 25.Demertzi A, Schnakers C, Ledoux D et al (2009) Different beliefs about pain perception in the vegetative and minimally conscious states: a European survey of medical and paramedical professionals. Prog Brain Res 177:329–338Google Scholar