Abstract
Objective: To identify an optimal gaze angle for precisely
evaluating the function of vertical semicircular canals in video head
impulse test (vHIT) and draw a comparison on the performances among
three different systems for vHIT.
Design: Two-center prospective study.
Setting: Participants were sit 1.2 meters away from the wall in
a noise-proved room that dedicated for vHIT experiments. For the
gaze-angle projects, targets were placed on the wall sequentially at the
pre-marked lines for different angles. Duringthe comparison experiments,
similar settings were ensured in both hospitals, like distance to wall
and angle of staring. Same examiner performed the comparison between two
systems in one location.
Participants: 26 healthy participants were recruited in the
gaze-angle experiments, 16 of which were further involved in
inter-examiner tests. For the comparison projects, 9 and 13 participants
were recruited, respectively. Any participant with otologic or
vestibular disorders was excluded.
Results: Our research showed that instead of right ahead at 0
degree, when torsion applied at vertical semicircular canal planes,
25-degree is a better place to set the targets. At this angle, a more
accurate VOR gain was easier to be obtained. Besides, our evaluations of
three different systems showed that a new vHIT system, VertiGoggles
ZT-VNG-I (VG) performed as good as the long-tested OtometricsICS
impulse (Oto) and EyeSeeCam (ESC).
Conclusion: We proposed a new protocol to set the targets 25
degrees from right ahead after tilt head 45 degrees to evaluate vertical
canals during vHIT. Furthermore, the new VG system is good for clinical
practices.