vHIT gains were consistently equal to 1.0 in all age groups (20's to 60's), suggesting that abnormal criteria for vHIT gain (e.g. 0.8) and gain asymmetry (e.g. 8%) can be used, regardless of age. CSs were observed in about half of normal ears, suggesting that VOR is a hypometric system. The amplitudes and interaural difference of CSs were also similar in all age groups, suggesting that abnormal criteria for CS amplitude (e.g. 100°/s) and interaural difference (e.g. 40°/s) can be used, regardless of age.

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Vestibular migraine (VM) is a common disorder causing recurrent attacks of vertigo, and the diagnosis of VM is based on recurrent vestibular symptoms, a history of migraine, a temporary association between vestibular symptoms and migraine symptoms, and exclusion of other causes of vestibular symptoms. 1 Although 8-25% of patients with VM exhibit abnormal caloric results, 2-4 it has been reported that the abnormal rates of vestibular tests in the interictal period were found to be relatively high (66-70%) when the caloric test was combined with other vestibular tests. 2,5 The caloric test is the most widely used method for identifying the presence and side of lateral canal hypofunction. It uses a non-physiological stimulus which is a lowfrequency stimulus outside the range of the endolymphatic movement expected from natural head movements. The head impulse test is a more physiological test of the semicircular canals used for assessing the high-frequency angular VOR. There have been a few studies regarding the results of vHIT in patients with VM. 6,7 In our study, we compared the abnormal rates of caloric and vHIT in 36 VM patients and in 23 VN patients who completed vestibular examination during the acute stage and at 1-month follow-up. We also addressed the difference in the correlation between the caloric and vHIT in both vestibular disorders. The VN patients at 1-month follow-up are supposed to have vestibular compensation and which is comparable to VM patients who underwent vestibular examination during the interictal period. Patients and methodsThe VM group based on the recent criteria for VM 1 was comprised of 36 patients (29 females, seven males; mean age 42.1 years; range 10-76 years). The average duration of vertigo symptoms was 15.9 AE 83.9 months. The VN subjects consisted of 23 patients diagnosed with acute unilateral VN and who completed vestibular examination during the acute stage (within 1 week after the onset of vertigo) and 1 month later. Patients exhibiting signs and symptoms of other peripheral vestibular disease, bilateral VN, and central vestibular disease were excluded from our study. Ethical considerationsThis study was approved by the Institutional Review Board of the institution. Caloric testsThe bithermal caloric test using cold and warm water irrigations was performed, and eye movements were recorded by a video-based system (CHARTR VNG; ICS Medical, Schaumburg, IL, USA). Jongkees formula was used to determine canal paresis which was considered pathological when it was ≥20%. Caloric responsiveness was defined as the sum of the slow-phase eye velocities (SPVs) induced by both warm and cold irrigation and compared in the lesioned and intact ears of VN. In VM patients, caloric responsiveness was calculated in each ear with weak and strong caloric responses. Video Head impulse test (vHIT)The device used for vHIT was ICS Impulse (GN Otometrics, Taastrup, Denmark, http://www.icsimpulse.com). Subjects were seated wearing goggles facing the wall, with a distance of 1 m from a small LED target on...