Vestibulopathy and age effects on head stability during chair rise

It is unknown how vestibular dysfunction and age differentially affect balance control during functional activities. The objective of this study was to gain insight into the effects of age and vestibulopathy on head control when rising from a chair. Head relative to trunk (head-on-trunk) sagittal plane angular and linear control strategies were studied in patients with bilateral vestibular hypofunction (BVH) and in healthy subjects aged 30-80 years. A two-way analysis of variance was used to compare head-on-trunk kinematics by age (young vs elderly) and diagnosis (healthy vs BVH) at the time of liftoff from the seat. Angular control strategies differed with age but not diagnosis: young (healthy and BVH) subjects stabilized head rotations in space while elderly (healthy and BVH) subjects stabilized head rotations on the trunk. In contrast, linear control strategies differed by diagnosis but not age: BVH subjects (young and old) allowed a greater rate of head-on-trunk translation while healthy subjects (young and old) inhibited such translations. Young BVH subjects stabilized head-in-space rotations (as did young healthy subjects) without a functioning vestibular system, suggesting cervicocollic reflex and/or other sensory compensation for vestibular loss. Elderly BVH subjects stabilized head rotation with respect to the trunk, as did healthy elders, but did not stabilize head-on-trunk translations, suggesting a reliance on passive mechanical responses of the neck to sense head movements. We conclude that compensation strategies used by patients with vestibulopathy are age-dependent and appear to be more tractable in the younger BVH patient.