Vestibulo-ocular reflex dysconjugacy associated with central cause of dizziness

Most current video head impulse test (vHIT) systems take monocular recordings, which is sufficient to identify a peripheral vestibulopathy. Given central ocular motor abnormalities can cause dysconjugacy between the eyes, binocular vHIT may help further identify central/dangerous lesions. Here, we examined the utility of binocular vHIT to differentiate central from peripheral vestibulopathy.

We enrolled three groups: healthy volunteers, consecutive patients with peripheral vestibulopathy, and consecutive patients with central vestibulopathy, respectively. All subjects underwent binocular vHIT, with vestibulo-ocular reflex (VOR) gains of each eye recorded individually. We calculated various measures of VOR gain conjugacy, including intra-class correlation coefficient (ICC), the VOR difference (VORD), and the VOR ratio between the two eyes. The absolute values of VORD (|VORD|) were compared across groups.

We enrolled 48 healthy controls, 37 patients with peripheral vestibulopathy, and 17 patients with central vestibulopathy. In rightward impulses, the ICC was 0.89 in controls, 0.98 in the peripheral group, and 0.78 in the central group. In leftward impulses, the ICC was 0.76 in controls, 0.93 in the peripheral group, and 0.71 in the central group. The |VORD| was higher in the central group (mean ± SD: 0.12 ± 0.16) compared to the peripheral group (0.05 ± 0.04, p = 0.02) and healthy controls (0.05 ± 0.03, p = 0.02).

Binocular vHIT can measure the VOR gain consistency between two eyes. A finding of high-degree VOR inconsistency should increase clinical suspicion for central vestibulopathy.