Our study had several limitations. First, highly selected patients from a neurology clinic at a regional university hospital were recruited. The sample size was small, and the study used a cross-sectional design that provided limited causal information. Second, the present data did not identify statistically significant correlations between VEMP parameters and headache clinical parameters such as frequency, duration, and intensity (data not shown). Additionally, this study was based on outpatient subjects and only administered the headache questionnaire at the first visit; therefore, detailed headache characteristics recorded using a headache diary should be considered in future studies to more accurately identify the correlations between electrophysiological data and headache parameters. Furthermore, prospective longitudinal studies including information regarding impact or disabilities due to headache may be warranted. Third, sound stimulation was applied at 500 Hz, which showed a 100 % response rate in both oVEMP and cVEMP of healthy subjects [47]. However, VEMPs were not obtained in approximately 8-10 % of subjects in the control group, as previous studies showed similar results [14, 16]. oVEMP and cVEMP predominantly represent saccular stimulation, and bone vibration activates both utricular and saccular afferents [4]. Thus, we should consider the use of a bone vibrator in future studies.