This study aimed to examine the association between caloric asymmetry and response to treatment in patients with vestibular migraine.

Dizziness Handicap Inventory scores were compared between patients with less than and more than 25 per cent asymmetry (using Cohen effect size) in a cohort of definite vestibular migraine patients who underwent caloric testing between August 2016 and March 2019.

A total of 31 patients (mean age: 48.7 ± 20.0 years; mean follow up: 9.1 ± 8.1 months) were included. Mean caloric asymmetry was 15.1 ± 15.6 per cent, with 6 (19.4 per cent) patients having asymmetry more than 25 per cent. Overall, patients experienced significant improvement in Dizziness Handicap Inventory total (d = 0.623 (95 per cent confidence interval, 0.007, 1.216)), emotional domain (d = 0.635 (95 per cent confidence interval, 0.019, 1.229)) and functional domain (d = 0.769 (95 per cent confidence interval, 0.143, 1.367)) but not physical domain (d = 0.227 (95 per cent confidence interval, −0.370, 0.815)) scores. Patients with more than 25 per cent asymmetry had no significant improvement in Dizziness Handicap Inventory scores, whereas those with less than 25 per cent asymmetry had significant improvement in Dizziness Handicap Inventory functional domain scores only (d = 0.636 (95 per cent confidence interval, 0.004, 1.244)).

Vestibular migraine patients with peripheral vestibular weakness on caloric testing may be less likely to improve after treatment compared with those without.