On-off asymmetries of responses to caloric step stimuli.

Rapid head movement was combined with continuous caloric irrigation of the external ear to evaluate the time courses of the on-step (null-to-supine repositioning) and off-step (supine-to-null repositioning) vestibulo-ocular reflexes (VOR) responses in eight healthy subjects. During continuous air-caloric irrigation, each subject's head was positioned with his/her lateral semicircular canal alternately placed in the null (horizontal) and activating (vertical) planes, and the time course of the slow phase eye velocity was evaluated. The resulting responses were characterized by estimates of activation and adaptation components, and their amplitudes and time constants were calculated.

Postural stability during visual stimulation and the contribution from the vestibular apparatus.

Conclusion: When combined with vestibular dysfunction, visual flow can exacerbate reductions in postural stability. This effect may be one of the mechanisms underlying visual vertigo, which can be evaluated using frequency analysis of body sway elicited by optokinetic stimulation (OKS).

Objective: To clarify the interaction between the postural responses to visual flow and to input from the vestibular apparatus as a mediator of visual vertigo.

Ocular flutter associated with a lesion of the right upper pontine tegmentum.

Ocular flutter is a relatively rare eye movement disorder characterized by intermittent bursts of conjugate horizontal saccades without an intersaccadic interval. Its anatomical and neurophysiological basis remains controversial. Here we present a case of ocular flutter in which the flutter declined as the clinical stage of the associated ailment declined, until it eventually disappeared.