Learning Objectives:
Introduction: The vHIT investigates the vestibular function in two ways: a VOR (vestibulo-ocular reflex) gain value and a graphical representation of VOR. Interpreting patient's vestibular function based on vHIT depends on both parameters, but more information about the reliability of the two parameters is needed.
The objective was to investigate the reliability of vHIT by comparing gain values between examiners on the same subjects and to see how differences affected the occurrence of saccades.
Method: Thirty subjects who had undergone cochlear implant (CI) surgery, were tested with video head impulse test (EyeSeeCam from Interacoustics). Four different examiners, all experienced with vHIT, tested the subjects.
Two judges interpreted the graphical representation of VOR according to occurrence of saccades or not.
Results: Differences in gain values amongst examiners varied from 0.2–0.58 with an average of 0.14 (95% CI 0.12–0.16) on the right ear and 0.17 (95% CI 0.15–0.19) on the left ear. Occurrences of saccades on the same patient were reproduced in 93% of the cases by all examiners. Interclass correlation coefficient (ICC) of the gain values between two examiners was 0.62. Kappa's coefficient was calculated upon the interpretation of the graphical outcome to 0.83.
Conclusion: The gain value seems to be less reliable than the graphical occurrence of saccades in the judgement of VOR. Interpretation of vHIT results should therefore not depend on the gain value alone but should depend on both gain value and the occurrence of saccades.
