Analysis of the fast phase of per-rotatory nystagmus

We studied the relationship between the fast phase velocity and amplitude of per-rotatory nystagmus resulting from constant angular acceleration and deceleration stimulation. The relationship was nonlinear and was best fit to the exponential equation. We established the uppermost point of the data distribution along the resolution curve. In normal subjects the angular rotatory stimulation using a computer-controlled rotatory chair (ROKOS-6) with 5 degrees/s2 rotation was the best among three kinds of angular rotatory stimulation (1.2 and 5 degrees/s2). Compared to peripheral vestibular disorder the uppermost point of nystagmus had a tendency to be larger in amplitude in some cases with central vestibular disorder. In many cases with sudden deafness the same tendency was seen.