Detection of the unilateral vestibular recruitment phenomenon using the rotation test

The possibility of detecting unilateral vestibular recruitment using the rotation test was examined. According to the analogy model of cochlear recruitment, the directional difference of rotation nystagmus reaches its maximum at the threshold stimulus intensity of the affected ear when recruitment is present, and the predicted maximum directional difference remains within the normal variation range when the contribution from the spontaneous nystagmus is removed. Moreover, there was no difference in the positive ratio of recruitment in the rotation test between the two groups evaluated as having positive and negative recruitment on the caloric test. From these results, detection of the unilateral vestibular recruitment phenomenon, when similar to the cochlear recruitment, was concluded to be difficult using the rotation test.