Two Cases in Which the Effectiveness of Vestibular Rehabilitation was Evaluated Objectively Using the Dynamic Visual Acuity (DVA) Test and Functional Vision Head Impulse Test (fvHIT)

Abstract

Objective: Vestibular rehabilitation (VR) outcomes are conventionally assessed using subjective measures such as the Dizziness Handicap Inventory (DHI) and posturography. The dynamic Visual Acuity (DVA) test and Functional Vision Head Impulse Test (fvHIT) are emerging functional tools, but their utility for assessing VR outcomes remains underexplored. Methods: We performed the video head impulse test (vHIT), DVA test, fvHIT, and posturography at two time points in two patients undergoing VR. Case 1 was that of a 41-year-old man who developed mild left vestibular hypofunction following sudden sensorineural hearing loss with vertigo. Case 2 was that of a 65-year-old woman with bilateral vestibular hypofunction suspected as having been caused by aminoglycoside ototoxicity. Results: In Case 1, in whom the vestibular impairment was mild at baseline, the results of the vHIT, DVA test, fvHIT, and posturography showed no significant differences between measurements, indicating that little functional deterioration requiring central compensation was present. In Case 2, the vHIT gain remained unchanged between the two time points; however, the DVA improved (left: 1.4 to 1.0 logMAR), the result of the fvHIT showed marked improvement (e.g., LP: 13% to 92%), and posturography showed normalization (closed-eye path length: 695 to 297 cm). Conclusions: The contrast in the test results between the two cases, which differed in the severity of vestibular impairment, suggests that the DVA test and fvHIT can objectively capture functional recovery that remains undetectable by vHIT alone, supporting their utility as tools for assessing the outcomes of vestibular rehabilitation.