Background factors in patients with compensated video head impulse test gain after vestibular rehabilitation therapy

Objectives: A few patients with chronic vestibular dysfunction have shown improved video Head Impulse Test (vHIT) gain after vestibular rehabilitation therapy (VRT), whereas others have shown either slight improvement or remained stable. Therefore, we investigated whether some specific factors affected the vHIT gain after VRT. Methods: Six hundred and eighty-six patients with intractable vertigo/dizziness who were hospitalized for neuro-otological examinations at the Vertigo/Dizziness Center of Nara Medical University between July 2014 and October 2023 were enrolled. In addition, patients who had a vHIT gain < 0.8 for the semicircular canal at the time of their first visit to our hospital and had undergone 6 months of VRT were included in the study. Patients were divided into two groups: VRT-C included participants with a vHIT gain of >= 0.8, and VRT-R included those with a vHIT gain of < 0.8 after 6 months of rehabilitation. We investigated factors such as age, illness duration, maximum slowphase eye velocity (mSPV) in the caloric test (C-test) for the dysfunctional ear, mSPV in the C-test for the functional ear, subjective visual vertical, ocular vestibular-evoked myogenic potentials, and cervical vestibular-evoked myogenic potentials. Results: Twenty-seven patients were enrolled in this study (21 in the VRT-R group and six in the VRT-C group). The VRT-C group had a shorter illness duration than the VRT-R group (p = 0.0056, Mann-Whitney U test). In the dysfunctional ear C-test, the mSPV was significantly greater in the VRT-C group than in the VRT-R group (p = 0.0205, Mann-Whitney U test). No differences were observed between the two groups in terms of other factors. Conclusion: VRT may improve vHIT gain in patients who can undergo it earlier and those with larger mSPV values in the C-test for dysfunctional ears. However, other studies have identified several factors influencing the effectiveness of VRT. However, further research is required to confirm this hypothesis.