Influence of hearing on vestibulospinal control in healthy subjects.

Abstract

Balance control is based on multisensory interaction. In addition to vestibular, proprioceptive and visual information, it seems that auditory input also plays an important role. The aim of the study was to investigate the effect of hearing on vestibulospinal coordination and to obtain deeper knowledge about mechanisms of audiovestibular interaction. In normal hearing, healthy subjects who performed the Unterberger (Fukuda) stepping test with and without frontal presentation of noise, the distance of displacement, the angle of displacement and the angle of rotation were measured by means of ultrasound based cranio-corpo-graphy (CCG). Additionally, subjective estimation of the effect of auditory input was compared to objective test results. In the noise condition, there was asignificant improvement in the distance of displacement (mean with noise 66.9 cm± 33.5 standard deviation, SD, mean without noise 77.0 cm±32.7 SD, p< 0.001) and in the angle of rotation (mean with noise 14.2°± 10.1 SD, mean without noise 28.3°± 20.2 SD, p< 0.001), while no difference was found within the conditions regarding the angle of displacement (mean with noise 29.1°± 33.5 SD, mean without noise 30.0°± 34.0 SD, p= 0.641). Side-specific analysis revealed apositive correlation between angle of displacement and angle of rotation in the condition without noise (Spearman r = 0.441, p< 0.001). The rate of agreement between subjective estimation of noise influence and objective test results ranged between only 43% and 63%, depending on the question and endpoint. Hearing had aclearly beneficial effect of auditory inputs on vestibulospinal coordination, especially for distance of displacement and angle of rotation.