Latency Time of Vestibular Nystagmus in Repeated Bidirectional Rotatory Stimulation

Abstract

A total of 77 healthy subjects underwent repeated, identical acceleration in the clockwise and counterclockwise directions. The case material was divided into three groups, with stimulation at l°/sec², 3°/sec² and 5°/sec². The latency times are found to increase somewhat in successive stimulation in alternating directions at l°/sec², whereas no such increase is noted at 3°/sec² and 5°/sec². The coefficients of variation of the latency times are similar in all groups. The mean difference between the latency times in clockwise and counterclockwise acceleration in the different groups is almost constant in repeated tests.

It is concluded that one rotatory test does not affect the results of the next test. It is also found that the latency times are somewhat longer in clockwise acceleration than in counterclockwise, irrespective of the direction of the first acceleration. Altogether 33% of the subjects have a shorter latency time in acceleration in one direction in all three tests. In 9% this applies to clockwise acceleration, and in 24% to counterclockwise acceleration.