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Open Access Highly Accessed Research article

Assessment of visual fixation in vegetative and minimally conscious states

Haibo Di12*, Yunzhi Nie1, Xiaohua Hu13, Yong Tong14, Lizette Heine2, Sarah Wannez2, Wangshan Huang1, Dan Yu13, Minhui He1, Aurore Thibaut2, Caroline Schnakers2 and Steven Laureys2

Author Affiliations

1 International Vegetative State and Consciousness Science Institute, Hangzhou Normal University, 310036 Hangzhou, China

2 Cyclotron Research Centre and Neurology Department, Coma Science Group, University and University Hospital of Liege, Liege, Belgium

3 Wujing Hospital of Hangzhou City, Hangzhou, China

4 Huzhou Center Hospital, Huzhou, China

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BMC Neurology 2014, 14:147  doi:10.1186/1471-2377-14-147

Published: 16 July 2014

Abstract

Background

Visual fixation plays a key role in the differentiation between vegetative state/unresponsive wakefulness (VS/UWS) syndrome and minimally conscious state (MCS). However, the use of different stimuli changes the frequency of visual fixation occured in patients, thereby possibly affecting the accuracy of the diagnosis. In order to establish a standardized assessment of visual fixation in patients in disorders of consciousness (DOC), we compared the frequency of visual fixation elicited by mirror,a ball and a light.

Method

Visual fixation was assessed in eighty-one post-comatose patients diagnosed with a MCS or VS/UWS. Occurrence of fixation to different stimuli was analysis used Chi-square testing.

Result

40 (49%) out of the 81 patients showed fixation to visual stimuli. Among those, significantly more patients (39, 48%) had visual fixation elicited by mirror compared to a ball (23, 28%) and mirror compared to a light (20, 25%).

Conclusion

The use of a mirror during the assessment of visual fixation showed higher positive response rate, compared to other stimuli in eliciting a visual fixating response. Therefore, fixation elicited by a mirror can be a very sensitive and accurate test to differentiate the two disorders of consciousness.

Keywords:
Disorders of consciousness; Vegetative state; Unresponsive wakefulness syndrome; Minimally conscious state; Visual fixation