The Use of vHIT in the Differential Diagnosis Between Vestibular Migraine and Meniere’s Disease: A Systematic Review and Meta-Analysis

<b>Background/Objectives:</b> The diagnosis of vestibular migraine (VM) and Meniere's disease (MD) is based mainly on clinical criteria. The aim of this study is to systematically review and investigate the potential role of the video Head Impulse Test (vHIT) in the differential diagnosis between VM and MD. <b>Methods:</b> A systematic review of the English-language literature was conducted, including studies from database inception to November 2023, in accordance with PRISMA guidelines. Medline (via PubMed), Cochrane Database and Scopus were reviewed. The review included studies involving adult patients diagnosed with VM, MD, or healthy control individuals who underwent vHIT and reported data on vHIT abnormalities, gain, and refixation saccades. The AXIS tool was applied for risk of bias assessment in all cross-sectional studies. A random-effects meta-analysis was performed to compare vHIT gains between individuals with VM and those with MD. <b>Results:</b> Eleven cross-sectional observational studies with a case-control comparison design were included, comprising a total of 362 patients with VM, 307 patients with MD, and 135 healthy control subjects. All studies applied the same diagnostic criteria for VM; however, varying criteria were used for the diagnosis of MD. Four studies evaluated the duration of vestibular symptoms, two assessed migraine duration, and six provided a rationale for excluding individuals with overlapping VM and MD diagnoses. Criteria for defining an abnormal vHIT result were specified in six studies. Seven studies reported vHIT gain values for the lateral semicircular canal, while eight presented data on saccade incidence and characteristics. Additionally, four studies were included in the meta-analysis, which yielded a mean difference in the vHIT gain of -0.0203 (95% CI: -0.0789 to 0.0383; <i>p</i> = 0.4968), indicating no statistically significant difference between patients with VM and those with MD. <b>Conclusions:</b> In this review, vHIT gain did not differ significantly between VM and MD groups, suggesting that vHIT gain alone has limited utility in their differential diagnosis. Combined saccade patterns may still prove clinically useful as more robust and consistent data become available.