Effect of labyrinthine dysfunction upon head oscillation and gaze during stepping and running.

Head oscillations and eye movements when stepping and running were studied in normal subjects and in patients with labyrinthine dysfunctions. In normal subjects, whereas linear head oscillations in the horizontal plane were very limited during both stepping and running, a marked increase in the vertical linear displacement induced pitching motions of the head during running. Patients with unilateral and bilateral lesions complaining of oscillopsia manifested lateral and diffuse oscillations, respectively, in the horizontal plane during stepping. The ratio of eye amplitude to head amplitude in the vertical plane showed larger values in subjects with labyrinthine lesions than in normals. The present results suggested that oscillopsia during upright locomotion is closely related to linear head oscillations with irregular and high-frequency components, in addition to dysfunction of the vestibulo-ocular reflex.