Vestibular disorders and dual task performance: impairment when walking a straight path

Abstract

Locomotion is impaired in some people with vestibular disorders. Performance on cognitive tasks is also impaired in many people with vestibular disorders. The goal of this study was to determine if patients with vestibular disorders have decreased ability to complete a dual task performance involving a cognitive task, an additional motor task or both tasks, combined along a linear path. Subjects were normal, had benign paroxysmal positional vertigo, or had various vestibular disorders that caused unilateral weakness. They were asked to walk 7.62 m in a straight line with eyes open or closed, without extra tasks, and while nodding the head, naming things, and both nodding and naming. The patients walked significantly slower than controls, especially when performing the cognitive task. Patients had greater ataxia and began veering sooner than normals. The subjects' veering increased significantly with the addition of cognitive tasks. The patient groups did not differ significantly from each other. The changes in velocity did not affect the veering. These data suggest that patients with vestibular disorders are impaired in their ability to complete a linear path when cognitive tasks are added.

Figures

Fig. 1

Diagram of the task for a subject who veered to the left. Subjects were instructed to start at the starting line and walk the distance, T. (Feet are not to scale.) Subjects who veered to either side walked some distance, d, to point V, at which they veered some angle, ϕ, continuing along the trajectory, h, to cross the finish line at point a, h, having moved laterally through some distance, a. For subjects who veered, the total distance walked was h + d. h = the square root of a2 + b2, when b = T – d and T = 7.62 m. Subjects who did not veer walked distance d + b, and d + b = T, or 7.62 m. (Reference . Used by permission of IOS press).

Fig. 2

Change in veer onset with eyes closed over the four conditions for the 3 groups. The top and bottom of the box represent the 75th and 25th percentiles respectively, the middle line is the 50th percentile, the whiskers extending from the top and bottom of the box represent the 90th and 10th percentiles, with the circles as outlier caps. BPPV = benign paroxysmal positional vertigo, variable = various vestibular disorder group.

Fig. 3

Change in velocity with eyes open (A) and eyes closed (B) over the four conditions for the 3 groups. The top and bottom of the box represent the 75th and 25th percentiles respectively, the middle line is the 50th percentile, the whiskers extending from the top and bottom of the box represent the 90th and 10th percentiles, with the circles as outlier caps. BPPV = benign paroxysmal positional vertigo, variable = various vestibular disorder group.

Fig. 4

Change in angle with eyes closed over the four conditions for the 3 groups. The top and bottom of the box represent the 75th and 25th percentiles respectively, the middle line is the 50th percentile, the whiskers extending from the top and bottom of the box represent the 90th and 10th percentiles, with the circles as outlier caps. BPPV = benign paroxysmal positional vertigo, variable = various vestibular disorder group.