Detection of receiver location and migration after cochlear implantation using 3D rendering of computed tomography

Objectives: The purpose of this study was to objectively evaluate the position and migration of the cochlear implant receiver and ball electrode using 3-dimensional (3D) rendering of computed tomography. Study Design: Retrospective case review. Setting: Tertiary referral center. Patients: Thirty-one patients were treated for profound sensorineural hearing loss with cochlear implant. The operative methods were divided into 2 groups: an inverted J-shaped incision with bony tie-down suture, and a minimally invasive incision without tie-down suture. INTERVENTION(S): When the receiver and ball electrode were detected in 3D imaging, the zygomatic process-receiver angle (ZRA), ear canal to receiver distance (ERD), and ear canal to ball electrode distance (EBD) were measured. Main Outcome Measure(S): Comparison and statistical analysis of postoperative angle and distances. Results: The mean ZRA, EBD, and ERD values were 139.1 degrees, 20.7 mm, and 36.0 mm, respectively. The mean ZRA in patients with an inverted J-shaped incision was significantly wider than for those with a minimally invasive incision (151.2 versus 136.9, p = 0.002). In 10 patients who received postoperative computed tomography 2 times, ZRA increased from 138.6 to 144.4 degrees (p < 0.001) and ERD decreased from 37.0 to 34.9 mm (p = 0.001). Conclusion: 3D computed tomography is a useful tool for localization and migration of the receiver and ball electrode. Micro downward movements of the receiver were found in both bony tie-down and non-tie-down suture groups.