Assessing the Vestibulo-ocular Reflex of Contralesional Sides According to Head Impulse Velocity Utilizing the Video Head Impulse Test in Patients with Vestibular Neuritis

BACKGROUND: There is a lack of comparative studies examining changes in vestibulo-ocular reflex ( VOR) gain with head velocity in the video head impulse test (vHIT) of patients with vestibular neuritis ( VN). Thus, the purpose of present study was to identify the effect of head impulse velocity on the gain of the VOR during the vHIT in patients with VN. METHODS: Head impulse velocities ranging from 100%-200 degrees/s [158.08 +/- 23.00 degrees/s in the horizontal canal (HC), 124.88 +/- 14.80 degrees/s in the anterior canal (AC), and 122.92 +/- 14.26 degrees/s in the posterior canal (PC) were used during vHIT trials of 32 patients with VN. Differences in VOR gain on the ipsilesional and contralesional sides according to head velocity were analyzed. RESULTS: The mean VOR gains in ipsilesional side were decreased to 0.47 in the HC and 0.56 in the AC, leading to marked asymmetry compared to the contralesional side; PC gain was relatively preserved at 0.82 in the ipsilesional side. The mean head impulse velocity applied during vHIT trials in each semicircular canal plane did not differ bilaterally. On the contralesional side, VOR gain was negatively correlated with head impulse velocity (R-2 = 0.25, P =.004 in HC; R-2 = 0.17, P =.021 in AC; R-2 = 0.24, P =.005 in PC), while VOR gain on the ipsilesional sides of the HC and AC was not. CONCLUSION: Head impulse velocity may have a differential impact on VOR gain, depending on the degree of deficit. Increasing head velocity in vHIT may be considered to identify subtle deficits on the contralesional side of patients with VN.