Abstract
Objectives:
Evaluate round window niche (RWN) visibility during cochlear implant (CI) surgery and to predict RWN visibility using high resolution computed tomography (HRCT).
Methods:
Sixty-five ears from 19 adults and 46 children who received CI were enrolled. All patients were examined with HRCT and their surgical video was recorded. In the axial slice showing RWN, a line was drawn along the posterior wall of the external auditory canal (line A). Another line (line B) parallel to line A was drawn to get contact with the vertical segment of the facial nerve. Relationship between the band between lines A and B and the position of the RWN was classified into 3 types: RWN was 1) fully, 2) partially, or 3) not included in the band. The visibility of the RWN during CI was classified as A) fully, B) partially, or C) not visible.
Results:
From the surgical video review, 27 cases were classified as A), 21 as B), and 17 as C). All the 15 cases classified as 3) based upon CT findings were classified as C). Out of 19 cases classified as 2), 17 were classified as B) and 2 as C). Out of 31 cases classified as 2), 27 were classified as A) and 4 as B).
Conclusions:
The visibility of the RWN during surgery exhibited high correlation with preoperative predictions from HRCT findings. This method is useful to preoperatively predict the difficulty of exposing the RWN in CI surgery.
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