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Quantitative assessment of visual behavior in disorders of consciousness

Journal of Neurology volume 259, pages 1888–1895 (2012)Cite this article

Abstract

The study of eye behavior is of paramount importance in the differential diagnosis of disorders of consciousness (DoC). In spite of this, assessment of eye movement patterns in patients with vegetative state (VS) or minimally conscious state (MCS) only relies on clinical evaluation. In this study we aimed to provide a quantitative assessment of visual tracking behavior in response to moving stimuli in DoC patients. Nine VS patients and nine MCS patients were recruited in a Neurorehabilitation Unit for patients with chronic DoC; 11 matched healthy subjects were tested as the control group. All participants underwent a quantitative evaluation of eye-tracking pattern by means of a computerized infrared eye-tracker system; stimuli were represented by a red circle or a small color picture slowly moving on a PC monitor. The proportion of on- or off-target fixations differed significantly between MCS and VS. Most importantly, the distribution of fixations on or off the target in all VS patients was at or below the chance level, whereas in the MCS group seven out of nine patients showed a proportion of on-target fixations significantly higher than the chance level. Fixation length did not differ among the three groups significantly. The present quantitative assessment of visual behaviour in a tracking task demonstrated that MCS and VS patients differ in the proportion of on-target fixations. These results could have important clinical implications since the quantitative analysis of visual behavior might provide additional elements in the differential diagnosis of DoC.

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Acknowledgments

The authors are profoundly indebted to Tullio Furlan and all the other patients’ relatives for their participation in the project; the authors thank Annamaria Saltalamacchia from the Salvatore Maugeri Foundation, Telese, Italy, for her support in collecting data.

Conflicts of interest

None.

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Affiliations

  1. Department of Psychology, Neuropsychology Laboratory, Second University of Naples, Via Vivaldi 43, 81100, Caserta, Italy

    L. Trojano

  2. Scientific Institute of Telese Terme (BN), Salvatore Maugeri Foundation IRCCS, Via Bagni Vecchi 1, 82037, Telese Terme, BN, Italy

    L. Trojano, P. Moretta, V. Loreto, A. Cozzolino & A. Estraneo

  3. Department of Neurological Sciences, Federico II University, Via Pansini 5, 81100, Naples, Italy

    L. Santoro

Authors
  1. L. Trojano
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  2. P. Moretta
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  3. V. Loreto
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  4. A. Cozzolino
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  5. L. Santoro
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  6. A. Estraneo
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Corresponding authors

Correspondence to L. Trojano or A. Estraneo.

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Trojano, L., Moretta, P., Loreto, V. et al. Quantitative assessment of visual behavior in disorders of consciousness. J Neurol 259, 1888–1895 (2012). https://doi.org/10.1007/s00415-012-6435-4

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  • DOI: https://doi.org/10.1007/s00415-012-6435-4

Keywords

  • Visual behavior
  • Visual tracking
  • Disorders of consciousness
  • Eye-tracker