Chapter

Postural Control and the Vestibulospinal System

John H. J. Allum and Mark G. Carpenter

in Oxford Textbook of Vertigo and Imbalance

Published on behalf of Oxford University Press

Published in print February 2013 | ISBN: 9780199608997
Published online February 2013 | e-ISBN: 9780191754227 | DOI: http://dx.doi.org/10.1093/med/9780199608997.003.0004

Series: Oxford Textbooks in Clinical Neurology

Postural Control and the Vestibulospinal System

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Vestibulo-spinal projections originate from different first-order vestibular neurons and course along different brainstem pathways from those of vestibule-ocular reflexes to spinal inter- and motor-neurons. Thus, based on descriptions summarized here, it is to be expected that the contribution of vestibulo-spinal reflexes to postural control during stance and recovery from perturbed balance will be very different too, and not predictable from responses of vestibulo-ocular reflexes. In order to describe these differences we first ask whether head movements during quiet stance indicate that vestibulo-spinal inputs could contribute to stabilising stance and, if so, what is the effect on the movement strategies used following bilateral vestibular loss (BVL). For the more common sudden unilateral vestibular loss (UVL) we show that recovery of normal balance control is different for stance and gait, that is, dependent on task complexity, and different from that of the vestibulo-ocular reflexes. An issue we mention briefly but requiring further investigation is the recovery of normal gait following UVL. During perturbations to stance, head movements are suprathreshold and prior to automatic responses leading to balance recovery. Thus the question arises how these supra-threshold vestibular signals contribute to balance recovery and whether these contributions are different along the body and different in lateral versus saggital directions, further, predictable from animal responses, bearing in mind the very different biomechanical responses of two-legged versus four-legged stance. An issue often neglected when studying vestibulo-spinal control of posture in man is how the very first balance correction is generated. Comparisons with adapted response described here may provide insights into fall prevention.

Chapter.  9105 words.  Illustrated.

Subjects: Neurology

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