[Horizontal semicircular canalvideo head impulse test in normaladults:normal value and age distribution]

Objective:To study the parameters of video head impulse test (vHIT) for horizontal semicircular canal and explore its application when evaluating angular vestibular-ocular reflex (VOR) in adults.Method:vHIT were applied to 80 adults without prior vertigo or dizziness history.Parameters provided by the software included instantaneous gain(40 ms,60 ms,80 ms),regression gain,asymmetry value,corrective saccades(latency,peak velocity,occurrence rate).Result:The mean horizontal VOR velocity gain of normal subjects was 0.877±0.171,0.944±0.133,0.967±0.130 at 40 ms,60 ms,80 ms respectively.Regression gain of horizontal VOR is 0.944±0.090.The lower limit of normal horizontal VOR velocity gain was 0.73 at 60 ms and 0.80 as regression gain.All velocity gains declined by age,although there were no statistically significant difference(P>0.05).Asymmetry value was 5.60±3.46.Corrective saccades occurred in 28±15 of normal subjects,while latency and peak velocity was (200.87±0.34)ms and (97.7±40.1)°/s.Conclusion:The study found that horizontal VOR instantaneous gain value and regression gain value decreases slightly with age,which should be considered in clinical application.