Statistical analyses
Statistical analyses were performed using ‘R’ (version 3.01; R Foundation for Statistical Computing, Vienna, Austria) and P-values <0.05 were considered to indicate statistical significance. The planned sample of 38 migraineurs and 46 healthy subjects resulted in a power of 90 % for detecting a 40 % reduction in the bilateral oVEMP response at a significance level of 0.05 using a two-sided Fisher’s exact test [16]. Additionally, the sample size calculation for the t-test to detect the difference in N1 latencies between the migraine and healthy control groups required 24 and 48 subjects, respectively. Data were expressed as the means ± standard deviation (SD) for continuous variables and as numbers (rates) for categorical variables. Continuous variables were compared using a two-sample t-test or Wilcoxon’s rank sum test, whereas categorical variables were evaluated using the χ2 test or Fisher’s exact test. Results of oVEMP and cVEMP parameters were compared among three subgroups. Multiple group analyses were performed using one-way analysis of variance (ANOVA) or the Kruskal-Wallis test. Pair-wise comparisons were assessed using the Wilcoxon’s rank sum test with Bonferroni correction.