Round window versus promontory stimulation: assessment for cochlear implant candidacy.

Electrical stimulation of the cochlea is a part of the preliminary evaluation protocol for cochlear implant candidacy at many centers. Typically, a transtympanic needle electrode is placed on the promontory of the ear under consideration and electrical current is presented to measure auditory percepts and psychophysical-electrophysiologic measures. Since 1984, we have used a ball electrode placed directly on the round window (via a tympanotomy) for stimulation, with 27 subjects being so tested to date. Nine additional subjects have had stimulating electrodes placed on both the round window and the promontory. Seven of these subjects yielded complete data. For measurements of threshold, maximum acceptable loudness level, and dynamic range, promontory testing mean values were higher than round window measurements. However, the differences were not significant.