Preoperative prediction of non-visuality of round window niche through posterior tympanotomy in cochlear implantation using Otoplan

Background Posterior tympanotomy (PT) is currently the standard approach to the round window (RF) for cochlear implantation (CI). The anatomy of the human temporal bone varies individually. Rarely, the RF cannot be visualized in the surgical field of view due to the unfavorable positional relationship, especially to the facial nerve. The Otoplan planning software provides a possible trajectory for the CI based on computed tomographic (CT) images. In the present work, we tested whether an expected frustrated RF visualization over the PT can be predicted using Otoplan.

Methods CT images of 28 human temporal bone specimens from cadavers and preoperative CT images of 30 patients for CI were analyzed using Otoplan with the question of whether at least one safe trajectory over the PT is possible. It was evaluated whether the intraoperative visualization of the RF over the PN in CI was consistent with the result of the previously performed Otoplan analysis.

Results In CT images of a temporal bone specimen as well as of a CI candidate, no safe trajectory could be found. In the other CT images, at least one safe trajectory could be shown through the PT. In the CI performed, the RF from one temporal bone specimen as well as from one patient could not be visualized via the PT, whose CT images did not show a safe trajectory. Intraoperative visualization of the RF via the PT was possible in the other temporal bone preparations and patients.

Conclusion In the present study, it was shown that CT analysis using Otoplan can be a suitable tool to predict already preoperatively an expected frustrated RF visualization through the PT.

Publication History

Article published online:
12 May 2023