Identifying the clinical signs on the healthy side using video head impulse test during different stages of vestibular neuritis

OBJECTIVE: To evaluate the presence of anti-compensatory saccades (AcS) using the video head impulse test (vHIT) in the healthy inner ear in patients with vestibular neuritis (VN) during the acute and subacute stages of VN. METHODS: We retrospectively considered a chart review of 2420 patients evaluated for acute vestibular syndrome from 2016 to 2020 in the Cassino (Italy) clinic. Nine hundred fifty-four patients with acute onset of vestibular syndrome who received an instrumental otoneurological assessment within 24 hours from the onset of the symptoms, evaluated by simultaneously using a combination of vHIT, ocular vestibular-evoked myogenic potential (VEMP), and cervical VEMP, were included in the study. RESULTS: Thirty-two patients with superior VN that showed an altered horizontal canal function when tested with vHIT and quick AcS on the healthy side were enrolled. We found that all patients with VN, evaluated in the first 24 hours from the onset of the symptoms, showed AcS when their head was abruptly and passively turned toward the healthy inner ear side. At follow-up within 8 weeks from the first evaluation, 29 out of 32 patients did not show increased AcS. CONCLUSIONS: Our findings support the hypothesis that the AcS on the healthy side are a clinical sign of vestibular canal hypofunction or paresis in patients affected by the acute stage of VN.