Presence of corrective saccades in patients with normal vestibulo-ocular reflex gain in video head impulse test

BackgroundThe video head impulse test (vHIT) is a valuable clinical tool that can help identify dysfunction of the semicircular canals. While in cases with semicircular canal dysfunction, both decreased vestibulo-ocular reflex (VOR) gain and corrective saccades (CS) are usually observed, there are cases which show CS despite normal VOR gain in vHIT.ObjectiveThis study aimed to investigate the clinical characteristics of patients who showed CS with normal VOR gain in vHIT.Materials and methodsAmong 390 patients who underwent vHIT, 51 patients (20 males and 31 females, age 31–87 years, average 61.3 years old) who showed CS with normal VOR gain unilaterally during horizontal vHIT were included. All patients had normal vHIT (normal VOR gain and absent CS) on the contralateral side.The VOR gain of vHIT, the maximum slow phase velocity in the caloric test, and the amplitude of cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs) were analyzed.ResultsThe VOR gain on the affected side (0.95 ± 0.08) was significantly smaller than that on the contralateral side (1.03 ± 0.13) in horizontal vHIT (p