Diagnostic role of cone beam computed tomography for the position of straight array

To assess the usefulness of cone beam computed tomography (CBCT) for characterizing electrode insertion and evaluate the influence of electrode insertion status on post-cochlear implantation (CI) outcomes.

Twenty-six ears with post-CI CBCT scans were included. The devices were MED-EL Flex28 (n = 21) and Nucleus slim straight (n = 5). The parameters including cochlear duct length (CDL), insertion depth angle (IDA), insertion length of electrode (IL), and cochlear coverage (CC) were analyzed and compared with aided pure-tone threshold (PTA) with implant in free field, and open-set sentence score.

The mean CDL was 36.8 ± 1.4 mm. Electrode array was dislocated into scala tympani in two ears. The mean IL and IDA were 26.5 ± 1.9 mm and 541.4 ± 70.2°. The mean linear CC (IL/CDL, 0.73 ± 0.06) was larger than the mean angular CC (IDA/900, 0.60 ± 0.08). The CBCT parameters showed correlation one another. While the aided pure-tone threshold was correlated with IL and IDA, there were no significant correlations in the open-set sentence score. For the postlingually deaf patients with single electrode (Flex 28), the sentence score had no significant correlation and the aided PTA was positively correlated with IL (R = 0.517, p = .028).

This study validated the CBCT evaluating the electrode array position. The CBCT could be helpful for the preoperative selection of the optimal array and prediction of the CC.