Evaluation of S-Value in relation to cochlear anatomy in pediatric cochlear implant users.

To assess the S-value in pediatric cochlear implant (CI) patients using high-resolution CT images and examine its correlation with main cochlear parameters and angular insertion depth (AID). A retrospective review of preoperative CT images from pediatric CI recipients with normal cochlear anatomy was conducted at a referral hearing implant center. Cases involving congenital or acquired inner-ear abnormalities were excluded. Two independent reviewers with equivalent expertise used OTOPLAN to measure the main cochlear parameters, and the interrater reliability study revealed good agreement. S-values (the straight section of the cochlear basal turn) were measured and examined, and their correlation to electrode insertion angles and cochlear parameters (A- and B-values) was evaluated. The average cochlear duct length (CDL) of the included patients was 36.14 ± 0.26 mm, with an average S-value of 7.06 ± 0.40 mm, insertion angle of 598.20° ± 48.72°, and cochlear coverage of 77.49% ± 0.57. A statistically significant relationship was found between A- and the S-values (r = 0.65, p = 0.004). However, the B-value showed a moderate, non-significant correlation with the S-value (r = 0.43). Furthermore, a consistent negative, but not statistically significant, association was found between the S-value and the angular insertion depths of all electrode contacts (r = - 0.28 to - 0.30). The S-value is a dependable anatomical parameter that correlates positively with the A-value. The evaluated lateral-wall array showed consistent insertion depths among patients with similar CDL, even when S-values differed. Further studies are needed to investigate the impact of greater variability in S-values on clinical outcomes and electrode-array position among CI users.