[New aspects of diagnostic criteria in BERA tests].

Abstract

The purpose of the presented work was to investigate the relationship between the length of I-III and I-V intervals during BERA examinations on the intensity of the stimulus in healthy subjects. Furthermore to assess the normal range of the maximum length of I-III and I-V intervals. Twenty-seven subjects aged 15-57 years, incl. 10 men, were examined. The stimuli were 100 us clicks, the repeating rate was 30/s, the stimulation intensity 0-85 dB nHL. The examination was made after administration of diazepam or rohypnol. TDH 49 earphones were used. Into the external auditory meatus on the examined side an electrode of the authors' own design in the shape of an open tube was introduced. The length of I-III and I-V intervals depended on the intensity of stimulation. The differences of mean values of the length intervals at stimulation intensities of 65 dB nHL and 45 dB nHL were statistically significant: p less than 0.02 for interval I-III and p less than 0.0001 for interval I-V. We take as the upper borderline of the normal length of intervals I-III approximately 2.8 ms and of intervals I-V 4.7 ms, if the latency of wave I is smaller than 2.5 ms. When the latency of wave I is greater, even longer I-III and I-V intervals may be still normal.