Reproducibility of duration of postacceleratory nystagmus

The value of 'Trapezoid Rotation Test' by Contraves computerized rotary chair system

Trapezoid Rotation Tests using the Contraves computerized rotary chair system were performed in 60 normal subjects and 213 patients with peripheral vestibular disorder. In normal subjects, directional preponderance was not observed. The so-called 'response decline phenomenon' by repeating the tests was not detected and the test results showed good reproducibility. On the other hand, the test results of patients were variable, in close relationship with the state of vertigo, and reflected patient's labyrinthine pathology so accurately that the inspection of the treatment course was possible by this testing system.

The dysrhythmia and the exponential constants of the postrotatory nystagmus qualities

In 5 healthy individuals the postrotatory, exponential constants were estimated for each of the four nystagmus qualities, viz. the velocities and durations of fast and slow components. The residual spread (Sr) of each quality in a semilogarithmic plot was also determined. The value of the constant for postrotatory decay indicated a decrease of the velocity and an increase for the duration of the slow component, both with a significant difference between individuals, while for the corresponding values of the fast components no systematic change in the postrotatory reactions was indicated, nor any difference between individuals. The constant that corresponds to the value at maximum stimulus showed differences between individuals for each of the four nystagmus qualities, while Sr presented differences between individuals only for the two slow phase qualities. This technique to describe postrotatory nystagmus reactions by the two exponential constants for each of the four nystagmus qualities together with the residual spread for each of the qualities is intended for future 'on-line' nystagmus analysis.