gms | German Medical Science

Introduction: Promontory Stimulation is a well-established tool to stimulate preoperatively the cochlea by a temporary transtympanic needle placed on the middle ear. It was shown that eABR recorded with Promontory Stimulation is an useful objective measure in CI candidates in testing and evaluating the presence and excitability of the auditory nerve and auditory pathway before cochlea implantation. This test is especially critical for a group of patient where it is hardly difficult or not even possible to judge the CI candidacy based on other pre-operative audiological tests. It was also demonstrated that a correct placement of the electrode tip on the RW niche, instead of the promontory, plays an important role on the efficacy of the electrical stimulation delivery.

Materials and methods: Subjects were candidates for a CI, and before CI implantation they underwent to the PromStim eABR test. For the pre-operative measurement, in local anaesthesia a trans-tympanic rounded-bent tip electrode was placed temporary on the RW niche and surface ground electrodes over the zygomatic bone and over the mandible angle; electrical impedance check and electrical stimulation was provided by the MED-EL Stimulator Box and was set by the MED-EL clinical software Maestro. Electrode placement was confirmed by IFT task where electrode impedance was 5 kOhm or lower.

Results: These preliminary data show the validity of PromStim test. The eABR were then later recorded by intra-op eABR elicited by CI electrode array, showing a good similarity with PromStim eABR and confirming the presence of responses.

Conclusion: PromStim eABR with MED-EL clinical system results easy to be used and feasible on CI candidates especially in whom the presence and excitability of the auditory nerve is in doubt.

Unterstützt durch: MED-EL Innsbruck

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