A (r = 0.749, P < 0.001). OT and UW were significantly dissociated with time (P < 0.001). For the 67 patients with MD, no correlation between the degree of OT and severity of UW was seen in MD group A. No significant dissociation change was revealed among the groups (P = 0.114). The OT abnormality is remarkable during the acute phase of VN, whereas it might not be remarkable immediately after a vertigo attack in MD. This finding can be used to differentiate MD and VN, especially when no definite hearing loss is seen or VN recurs.