This article is part of a series on Select Papers from the 2006 International Workshop on Virtual Reality in Rehabilitation, edited by Emily A Keshner, Patrice (Tamar) Weiss.

Research

Pairing virtual reality with dynamic posturography serves to differentiate between patients experiencing visual vertigo

Emily A Keshner^1,2,5 , Jefferson Streepey¹ , Yasin Dhaher^1,2,4 and Timothy Hain³

¹  Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Room 1406, 345 East Superior St., Chicago, IL 60611 USA

²  Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, 345 East Superior St., Chicago, IL 60611 USA

³  Department of Physical Therapy and Human Movement Science, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Ave., Chicago, IL 60611 USA

⁴  Biomedical Engineering Department, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3107 USA

⁵  Dept. of Physical Therapy, College of Health Professions, Temple University, Jones Hall 600, 3307 Broad St., Philadelphia PA 19140 USA

author email corresponding author email

Journal of NeuroEngineering and Rehabilitation 2007, 4:24doi:10.1186/1743-0003-4-24

Published:	9 July 2007

Abstract

Background

To determine if increased visual dependence can be quantified through its impact on automatic postural responses, we have measured the combined effect on the latencies and magnitudes of postural response kinematics of transient optic flow in the pitch plane with platform rotations and translations.

Methods

Six healthy (29–31 yrs) and 4 visually sensitive (27–57 yrs) subjects stood on a platform rotated (6 deg of dorsiflexion at 30 deg/sec) or translated (5 cm at 5 deg/sec) for 200 msec. Subjects either had eyes closed or viewed an immersive, stereo, wide field of view virtual environment (scene) moved in upward pitch for a 200 msec period for three 30 sec trials at 5 velocities. RMS values and peak velocities of head, trunk, and head with respect to trunk were calculated. EMG responses of 6 trunk and lower limb muscles were collected and latencies and magnitudes of responses determined.

Results

No effect of visual velocity was observed in EMG response latencies and magnitudes. Healthy subjects exhibited significant effects (p < 0.05) of visual field velocity on peak angular velocities of the head. Head and trunk velocities and RMS values of visually sensitive subjects were significantly larger than healthy subjects (p < 0.05), but their responses were not modulated by visual field velocity. When examined individually, patients with no history of vestibular disorder demonstrated exceedingly large head velocities; patients with a history of vestibular disorder exhibited head velocities that fell within the bandwidth of healthy subjects.

Conclusion

Differentiation of postural kinematics in visually sensitive subjects when exposed to the combined perturbations suggests that virtual reality technology could be useful for differential diagnosis and specifically designed interventions for individuals whose chief complaint is sensitivity to visual motion.