Pairing virtual reality with dynamic posturography serves to differentiate between patients experiencing visual vertigo
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BioMed Central
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Pairing virtual reality with dynamic posturography serves to differentiate between patients experiencing visual vertigo Emily A Keshner*1,2,5, Jefferson Streepey1, Yasin Dhaher1,2,4 and Timothy Hain3 Address: 1Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Room 1406, 345 East Superior St., Chicago, IL 60611 USA, 2Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, 345 East Superior St., Chicago, IL 60611 USA, 3Department of Physical Therapy and Human Movement Science, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Ave., Chicago, IL 60611 USA, 4Biomedical Engineering Department, Northwestern University, 2145 Sheridan Road, Evanston, IL 602083107 USA and 5Dept. of Physical Therapy, College of Health Professions, Temple University, Jones Hall 600, 3307 Broad St., Philadelphia PA 19140 USA Email: Emily A Keshner* - [email protected]; Jefferson Streepey - [email protected]; Yasin Dhaher - [email protected]; Timothy Hain - [email protected] * Corresponding author
Published: 9 July 2007 Journal of NeuroEngineering and Rehabilitation 2007, 4:24
doi:10.1186/1743-0003-4-24
Received: 12 January 2007 Accepted: 9 July 2007
This article is available from: http://www.jneuroengrehab.com/content/4/1/24 © 2007 Keshner et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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 n
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