Cochlear Implantation: First Experience with X-Ray Guided Anatomy-Based Fitting

This study presents a protocol for applying X-ray-guided anatomy-based fitting (ABF) in cochlear implant (CI) programming to reduce frequency-to-place mismatch. The goal is to improve alignment between the frequencies stimulated by each electrode and the natural tonotopic organization of the cochlea, thereby enhancing speech perception and auditory outcomes. Traditional default fitting (DF) methods don't account for individual variations in cochlear anatomy, leading to mismatches that can influence performance. In this prospective study, 16 ears from 12 CI users with normal cochlear anatomy were assessed using X-ray imaging to estimate angular insertion depth (AID) and guide the ABF protocol. Frequency assignments for each electrode were adjusted using OTOPLAN and MAESTRO software to match the cochlea's tonotopic map. Results showed that ABF significantly reduced the average frequency-to-place mismatch (2.6 ± 3.8 semitones) compared to DF (6.6 ± 5.6 semitones). ABF also showed a stronger correlation between AID and frequency shifts, with the most notable improvements in the mid-cochlear region. This protocol applies a low-radiation, accessible alternative to CT-guided ABF, particularly beneficial for pediatric or radiation-sensitive populations. X-ray-guided ABF demonstrates potential for more accurate CI programming and the potential to improve patient outcomes. Further studies with larger cohorts and longer follow-up periods are recommended to validate its clinical benefits.