Vestibular Dysfunction and the Leftward Deviation in the New Line Bisection Task Using Three-Dimensionally Transformed Rectangles.

Background/Objectives: The line bisection task (LBT) is a well-known test in which a horizontal line is presented in front of the subject and the subject is asked to draw a mark vertically bisecting the line. We developed the new LBT using three-dimensionally transformed rectangles to enhance the sense of depth and evaluated the influence of vestibular dysfunction on the deviation. Methods: One hundred participants were recruited from patients referred to the vertigo outpatient clinic. The average deviation in the LBT was the leftward deviation in the figures viewed from the right side and the rightward deviation in the figures viewed from the left side, indicating that the figures were perceived three-dimensionally, with the division point deviating to the far side. Results: In multivariate analysis of variance (MANOVA) analyses, the significant leftward deviation was observed in the group with vestibular dysfunction in caloric testing, and the significant rightward deviation dependent on increasing age was also observed. In univariate analyses, the significant leftward deviation in the figure viewed from the left side (135 degrees) was observed in the group with vestibular dysfunction in caloric testing, and the significant leftward deviation was also observed in figures viewed from the center, left or right side (0, 15 and 165 degrees) in the group with vestibular dysfunction in vHIT evaluation. Conclusions: Vestibular dysfunction can alter the deviation in the new LBT, suggesting the potential of the new LBT as an assessment of vestibular dysfunction.