[Comparative study of vestibular autorotation test and caloric test for patients with peripheral vestibular...

To analyse the value of vestibular autorotation test (VAT) for assessing vestibular function.

VAT (WSR. USA) and caloric test (CT) were performed on 48 patients with peripheral vestibular disorders. Videonystagmograph (Synapsis. France) was used for caloric nystagmus recordings. The results of VAT were compared with that of CT. Parameters analysed in this study included gain, phase and asymmetry of VAT; the canal paresis (CP) and the directional preponderance (DP) of CT. That any of five parameters of VAT was abnormal or one of CP and DP appeared could be defined as abnormal VAT or abnormal CT.

VAT was found to be abnormal in 36 (75.0%) patients, including 32 (66.7%) patients (21 cases with decreased gain, 24 cases with lagged phase and 6 cases with asymmetry) in horizontal testing and 15 (31.2%) patients (7 cases with decreased or increased gain, 14 cases with lagged phase) in vertical testing. Four patients had abnormal vertical testing alone. Abnormal phase can be observed more frequently than abnormal gain. The abnormal parameters of phase and gain were consistent in the 2.0-6.0 Hz range. Asymmetry appeared in all cases in the 6.0-11.0 Hz range, consistent with the side of vestibular weakness tested by CT. Thirty-three patients (68.8%) showed CP or DP of CT (bilateral or unilateral CP 28 cases and DP 16 cases). VAT and CT showed abnormal results in 25 patients simultaneously, solo abnormal results were found in 11 patients and 8 patients respectively. There were 4 patients with normal results of both VAT and CT. Abnormal results of VAT combined with CT were assessed in 44 (91.7%) patients. When vestibular lesion was complete, results of VAT and CT were all abnormal and the abnormal parameters of VAT were observed at all frequencies of band tested.

VAT is a vestibular test of high-frequencies and wide-bands and can indicate information of not only vestibular function in higher frequency band, but also vertical semicircular canal function. As the supplement of CT, error diagnosis can be partly avoided by VAT.