Evaluation of cochlea size as an influencing factor for hearing preservation in cochlea implantees

Introduction Preservation of residual hearing is the aim of modern cochlea implantation. Beside the electrode design and surgical technique, anatomical factors are assumed to be an important factor influencing the probability of residual hearing. Cochlea size affects the contact angle of electrode at the lateral wall and might influence force and pressure inside the cochlea during the insertional procedure. The aim of the study was to observe wheter the size of the cochlea has an impact on the probability of stable residual hearing of patients after cochlea implantation.

Methods In a retrospective study preoperative HRCT scans taken before cochlea implantation were measured to estimate the size of the cochlea. Surrogate parameters were cochlear diameter/ line A, width/ line B and height/ line C. A group of 20 patients with operatively non affected stable residual hearing (1 year) after CI implantation (group 1) (SlimJ, 622 and Flex 24,28) were compared with a control group of 60 patients without residual hearing or loss of residual hearing after CI implantation (group 2). The axial plane was defined as the reference plane in HRCT, and the cochlea was measured in coronal and sagital as the comparison plane using OTOPLAN program. The average value of determined sizes were compared between the groups.

Results Patients with residual hearing showed an average larger cochlea with a 4.1% larger diameter and 16% larger width. Both groups showed an average equal height of the cochlea of 3.43mm.

Conclusion Patients with larger cochlea seems to have a higher chance of preserve a stable residual hearing.

Publication History

Article published online:
12 May 2023