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

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.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).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(>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.The study found that horizontal VOR instantaneous gain value and regression gain value decreases slightly with age,which should be considered in clinical application.