Clinical Validity of Quantified Visually Enhanced Vestibulo-ocular Reflex Test to Detect Horizontal Semicircular Canal Hypofunction

Abstract

Objective: To investigate the clinical validity of the mathematical measured VVOR test results to detect horizontal semicircular canal hypofunction. Study Design: Prospective, nonrandomized, observational study. Setting: Tertiary referral center, hospital. Patients: Consecutive patients on first time visit to otoneurology unit. Intervention(s): Diagnostic. Main Outcome Measure(s): Values of statistical indicators of clinical validity for VVOR test to detect horizontal canal hypofunction were used considering vHIT horizontal aVOR gain values as gold standard. Results: Area under curve of ROC curve for quantified VVOR testing was 0.92. Head movement frequency on VVOR test and contralateral VVOR gain were identified as significant influence factors of (unilateral) VVOR gain (p < 0.0001) on statistical linear model. Conclusions: According to the obtained results, the quantified VVOR test has excellent clinical validity for detecting angular horizontal VOR hypofunction.

A review of the geometrical basis and the principles underlying the use and interpretation of the video head impulse test (vHIT) in clinical vestibular testing

“…Jorge Rey-Martinez tested the same patient over years and this patient consistently demonstrated enhanced eye velocity ( 41 ). The reliability has also been confirmed in repeated measures on other individual patients ( 42 , 43 ). The next question becomes: what could be the mechanism for such enhancement?…”

“…In testing vHIT, some patients show enhanced eye velocity and so VOR gains >1.0 (40)(41)(42). In many cases a VOR gain >1.0 is probably due to incorrect calibration, but we asked the question whether it is possible that changes in fluid dynamics could result in systematically enhanced VOR gain, in particular could enhanced VOR gain be an indicator of endolymph hydrops.…”

A New Method for Gain Calculation in Quantified Visuo‐vestibular Interaction Test

“…20 To date, no such suspected lack of accuracy has been evident in the papers published concerning quantified VVOR testing performed with a vHIT. In a large cohort of patients with vestibular disorders, Rey-Martinez et al 7 [7][8][9] Nonetheless, as suggested by all these authors, the emerging quantified VVOR method should be improved to achieve better VOR quantification accuracy.…”

“…Specifically, previous studies have observed that VVOR gain values in healthy individuals were significantly lower at higher stimulation frequencies, in particular, above 2 Hz. 7,17 The reasons for this gain decay at higher frequencies are not clear, but it has been suggested that it could be a lack of accuracy of pupil tracking of the vHIT device during VVOR test data recording. Nevertheless, other mechanisms could also influence this gain decay.…”

“…These authors have also described that at a higher range of frequencies, over 1 Hz, the VOR gain quantified in the (instrumented) VVOR test has a high correlation with vHIT VOR gain values. [7][8][9] To measure the VOR gain in vHIT, three different calculation methods have been described 10 :…”