We read with great interest the article by Zhang et al. examining the relationship between caloric testing and video head impulse test (vHIT) outcomes in unilateral peripheral vestibular disease 1. We commend the authors for addressing an important clinical question and offer several points to aid interpretation and guide future studies. A key finding of the study is that vHIT abnormalities become more predictable when caloric unilateral weakness (UW) exceeds 50%. However, this threshold should be interpreted descriptively rather than diagnostically. The authors cite evidence that caloric deficits as low as 22%–25% may be detectable on vHIT as they progress towards 40%–60% 2. While abnormal vHIT likelihood rises with UW > 50%, a normal vHIT in mild caloric weakness does not exclude vestibular dysfunction. Emphasizing this distinction is crucial to avoid overinterpretation in clinical practice and to support comprehensive vestibular assessment across the full spectrum of UW severity. The authors speculate that absent vHIT abnormalities at lower UW values may reflect sequential neuronal injury, with low-frequency pathways affected before high-frequency pathways. An alternative explanation is test-specific sensitivity. Caloric testing measures low-frequency responses to slow, sustained stimulation, whereas vHIT assesses high-frequency function during rapid head movements. Because these tests probe different domains, discordant results are common, occurring in up to 36.5% of patients 3. High-frequency deficits may not appear on vHIT until vestibular loss is more advanced, particularly in heterogeneous conditions such as Meniere's disease and vestibular neuritis 4. Thus, a normal vHIT at lower UW values should be interpreted cautiously and not assumed to represent intact high-frequency function. Two methodological points warrant discussion. First, inclusion was limited to patients with complete vestibular and audiological datasets. In a retrospective cohort of patients with acute vertigo, these criteria may exclude patients with severe symptoms or poor test tolerance, particularly during caloric testing, potentially introducing selection bias and limiting generalizability. Second, the study pooled multiple vestibular disorders despite their distinct pathophysiology. Meniere's disease characteristically shows dissociation between abnormal caloric responses and normal vHIT, whereas vestibular neuritis typically shows concordant abnormalities on both tests 4, 5. Analyses not stratified by diagnosis may obscure relationships between caloric testing and vHIT, potentially inflating or masking associations driven by individual subgroups. In conclusion, we commend Zhang et al. for an informative study and advocate for careful interpretation of caloric and vHIT findings, alongside methodological refinements, to advance understanding of vestibular function in peripheral disorders. N.J. designed the work; N.J. drafted, revised, and approved the manuscript; N.J. agrees to be accountable for all aspects of the work. A.L. contributed to manuscript drafting and editing; A.L. approved the manuscript and agrees to be accountable for all aspects of the work. A.J.S. contributed to manuscript drafting and editing; A.J.S. approved the manuscript and agrees to be accountable for all aspects of the work. S.R. contributed to idea conception and manuscript editing; S.R. revised and approved the manuscript and agrees to be accountable for all aspects of the work. M.A.C. contributed to manuscript editing and final approval; M.A.C. approved the manuscript and agrees to be accountable for all aspects of the work. The authors have nothing to report. The authors have nothing to report. The authors have nothing to report. The authors declare no conflicts of interest. Data sharing not applicable to this article as no datasets were generated or analysed during the current study.
Junedi et al. (Fri,) studied this question.