Transtympanic electrocochleograms were recorded in 15 patients with a sensorineural hearing loss at the different electrode positions. We have found another polarities of SP at the different electrode positions in some patients. In order to evaluate AP and SP amplitude, SP/AP ratio and polarity of SP, we therefore have recorded at four different positions with needle electrodes.
We have frequently observed dominant negative SP in electrocochleography for detecting endolymphatic hydrops in the patients with suspected Meniere's disease. However, Some investigators reported that positive SP was sometimes recorded in such cases. The purpose of this study is to clarify how the different SP polarities were recorded at the near round window niche and the other areas.
The results obtained were as follows.
1) Maximum AP and SP amplitude were recorded at the routine positions which we used.
2) Positive SPs were frequently recorded at the near position of the round window niche.
3) In electrocochleographic responses recorded by using the high frequencies, the incidence of negative SP was shown at low percentage, on the other hand, the positive SP was more frequently recorded at the near round window niche.
4) -SP/AP ratio was stable at every position.
5) It would be suggested that positive SP is mainly generated from the round window or the scala tympani of the basal turn.
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