Dynamic properties of feed back control of human posture in subjects with vestibular neuritis

Postural control was studied in 22 subjects with vestibular neruitis within 14 days after the onset of symptoms. Dynamic feed back control of posture were evaluated by analyzing the postural responses to vibration toward calf muscles applied according to a PRBS schedule. Properties of the dynamic control was normalized as swiftness, stiffness and damping of the responses. There was no prominent group differences between the 22 subjects with vestibular neuritis and 17 normal subjects. However, when studying the change in parameters evoked by presence or absence of visual information it was found that the abundant changes of control parameters, especially in stiffness, met in normal subjects had declined in subjects with vestibular neuritis. The present finding suggests that although subjects after an acute vestibular lesion may achieve a sufficient postural control by utilizing information from other somatosensory receptors, this is concomitant with changes of the feed back control.