Clinical implication of ocular torsion in peripheral vestibulopathy

Acute unilateral vestibular loss presents as ocular torsion (OT) and caloric unilateral weakness (UW). However, the amount of OT is frequently dissociated from UW depending on when the examination was performed and the extent and cause of the vestibular lesion. This study evaluated the relationship between OT and UW in peripheral vestibular diseases, including Ménière's disease (MD) and vestibular neuritis (VN), and determined whether it contributed to OT as a means of differentiating between the two diseases. A retrospective chart review was performed in 64 patients with VN and 67 patients with MD. We divided the patients into three groups according to the interval from symptom onset to when the tests were performed: within 7 (group A), from 8 to 30 (group B) and over 30 (group C) days. UW, OT and the chronological correlation/dissociation between the two parameters were analyzed. For the 64 patients with VN, the degree of OT and severity of UW were positively correlated in group 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.