Influence of acute unilateral vestibular lesions on the respiratory rhythm after active change of posture in human subjects.

The influence of acute unilateral vestibular lesions on respiratory rhythm after active change of posture, was evaluated by comparing responses from patients with acute vestibular neuritis, with those from normal subjects with minor injuries other than vestibular (e.g. epistaxis, headache) and patients with chronic bilateral vestibular dysfunction. Respiratory movements of the thorax-abdomen were recorded during 5 minutes in supine position, 5 minutes of back-unsupported sitting and 5 minutes of upright stance. Compared to supine position, sitting-up induced different responses in each group (p < 0.05, ANOVA). The healthy subjects showed a consistent decrease in the mean respiratory frequency related to an increase of the expiration time, which was absent in patients with vestibular neuritis. Subjects with minor injuries showed the opposite changes of expiration time and inspiration time with no change of the respiratory frequency and patients with bilateral vestibular dysfunction showed a trend to increase their respiratory frequency. Standing-up did not evoke any further changes in any group. We conclude that the vestibular system modulates the respiratory response to reorientation of the head and trunk to upright position and this influence is reduced during the acute stage of a vestibular lesion.