Normative Data on Angular Vestibulo-Ocular Responses in the Yaw Axis Measured Using the Video Head Impulse Test

Objective: To analyze vestibulo-ocular responses using the video head impulse test in the yaw axis. Study Design: Prospective. Setting: Tertiary and university hospital. Patients: Two hundred twelve healthy subjects with no history of vestibular or neurologic impairment. Intervention: Video head impulse test in the lateral semicircular canal plane. Main Outcome Measures: Vestibulo-ocular reflex (VOR) gain and appearance of refixation saccades (RSs) considering sex, age, and head impulse velocity and direction. Results: Mean gain was 1.06 +/- 0.07, and there were no differences between sexes. For all the impulses (n = 9,654; 4,947 rightward and 4,707 leftward), VOR gain decreased as head impulse velocity increased. When gain was evaluated by age and head velocity, it was steady until age 70 years for higher-velocity impulses and until age 90 years for lower-velocity head impulses. RSs were detected in 52 subjects, occurring after impulses to both sides of the head in 22 of these subjects. The number of subjects with RSs was significantly higher after age 71 years, and velocity was correlated, not with age, but with head impulse velocity. Conclusion: VOR gain was stable until age 90 years and thereafter dropped. However, this decrease occurred progressively in younger subjects as head impulse velocity increased, with VOR gain for faster head impulses decreasing significantly in subjects older than 70 years. This finding, in addition to the appearance of RSs, can be explained by the effect of aging on the deterioration of the vestibular system in the semicircular canals.