Can video head impulse testing aid differential assessment of suspected vestibular migraine attacks?

Vestibular migraine is a clinically defined disorder characterized by recurrent vestibular symptoms associated with migraine features, and its acute attacks may be difficult to distinguish from peripheral vestibular disorders such as acute unilateral vestibulopathy/vestibular neuritis, Ménière's disease, and vestibular schwannoma. This review synthesizes current evidence on the clinical interpretation and proposed pathophysiological context of video head impulse test findings during acute vestibular migraine episodes, with particular attention to vestibulo-ocular reflex gain, refixation saccades, and subjective visual vertical abnormalities. Available evidence suggests that vestibulo-ocular reflex gain is often preserved during acute vestibular migraine, although variable or transient reductions have also been reported, limiting its diagnostic specificity when used alone. Refixation saccades, including covert, bilateral small-amplitude, or occasionally unilateral high-amplitude patterns, have also been reported during acute vestibular migraine. However, these findings are non-specific and may also be associated with peripheral vestibular dysfunction, age-related variability, compensatory responses, gaze-fixation instability, or technical artifacts. When recording quality is adequate, their distribution and temporal evolution may provide adjunctive information, but they should not be used independently to infer a specific central mechanism or establish the diagnosis of vestibular migraine. Subjective visual vertical testing may provide complementary information on graviceptive perceptual imbalance that is not fully captured by vestibulo-ocular reflex gain. Because VM is diagnosed on clinical grounds, vHIT and SVV findings should be interpreted as non-specific adjunctive data within the Bárány Society and International Headache Society diagnostic framework and in conjunction with the clinical history and complementary vestibular and audiological assessments. Accordingly, vHIT and SVV may contribute to a multimodal differential assessment during VM attacks, but they do not define a specific pathophysiological subtype or replace the clinical diagnosis of VM.