We compared the results of analysis of vestibulo-ocular reflex (VOR) obtained by manual rotation with those of a caloric test performed at the interval of one hour, and examined the validity and limitations of VOR analysis as a test for the estimation of vestibular function and imbalance in routine vestibular clinical practice. VOR response was recorded by a manually rotating standard clinical chair for approximately 40 s. VOR gain was slightly, but significantly, correlated with the peak slow phase velocity of caloric response (r=0.253, p<0.05). However, patients with poor caloric response failed to exceed the range of two standard deviations of the mean value of normal subjects, indicating that it is clinically difficult to use VOR gain alone as an estimate of unilateral vestibular function. VOR directional preponderance (VOR-DP%) correlated well with caloric canal paresis (CP) (CP%; r=0.605, p<0.001). VOR-DP% was within the normal range in patients with caloric CP%<20 and exceeded the normal range in most subjects with caloric CP%>50. VOR-DP% varied widely when caloric CP% ranged between 20 and 50. Visual suppression in VOR(VSrot)correlated well with that in caloric test (VScal)(r=0.460, p<0.05). In all cases with VScal<40, VScal exceeded the normal range. These results indicate that determination of VOR-DP% and VSrot should contribute to the early diagnosis of fresh vestibular disorder, especially in daily clinical practice.
