Head and body center of gravity control strategies: Adaptations following vestibular rehabilitation

Objective - We present for the first time evidence that vestibulopathy impairs coordination of the head with the body center of gravity (CG) during free speed gait over ground. Vestibulopathic individuals demonstrate uncoordinated movement and gait due, at least in part, to impaired head stability and visual fixation. Vestibular rehabilitation increases speed and stability during gait and stair climbing, although the underlying mechanisms are poorly understood. Material and methods - To determine whether these locomotor improvements are due to reorganized coordination of the head with whole body CG, three-dimensional kinematics were obtained from 10 vestibulopathic individuals before and after vestibular rehabilitation and from 10 matched healthy control subjects during unconstrained, paced and in-place gait. Head control patterns were characterized using both qualitative pattern analysis and quantification of coherence between head and body CG displacements. Results - Patterns of head-CG coordination differ between normal and vestibulopathic individuals in all three directions of head rotation - pitch, roll and yaw - before rehabilitation. Following vestibular rehabilitation, subjects with vestibulopathy demonstrate more normal patterns in pitch and improvements toward normal in roll and yaw. Conclusion - These data strongly suggest that compensatory mechanisms, obtained during vestibular rehabilitation, mediate head-CG coordination.