Wideband absorbance measurements in cochlear implant recipients: Insights into the Transcranial Veria Technique

Cochlear implantation (CI) significantly improves hearing in individuals with severe to profound sensorineural hearing loss. However, variations in surgical techniques may affect middle and inner ear mechanics. This study explores the effect of transcranial transcanal wall-Veria technique for CI on middle ear mechanics, measured using wideband absorbance (WBA).

Ten children (4-7 years) who underwent CI using the transcranial Transcanal wall-Veria technique were compared to age- and gender-matched controls with normal-hearing children. Tympanometric measures such as static compliance, tympanometric peak pressure, Ear canal volume, resonance frequency, and wideband absorbance at peak and ambient pressure were measured.

Conventional 226 Hz Tympanometric measures were similar for both CI and Normal hearing groups, showing no significant differences (p > 0.05) between the groups. However, WBA measurements revealed significant changes (p < 0.05) in absorbance across frequencies, particularly at higher frequencies (2000-8000 Hz). The WBA pattern was different, with two maximum absorbance for normal-hearing children, whereas single maxima around 2000 Hz for CI group. Further, WBA at peak pressure differed from ambient pressure in both groups at low and mid-frequencies, with significant differences (p < 0.05) observed only in CI group. These results suggest that the Veria technique causes alterations in middle ear mechanics, specifically in the high-frequency regions.

This study highlights the utility of WBA in detecting subtle, frequency-specific changes in ear mechanics following the Veria CI technique, which may remain undetected by conventional tympanometry. Although functional auditory outcomes such as aided thresholds, speech perception scores, and eSRT were not correlated in this study,the findings underscore the importance of WBA as an advanced diagnostic tools in assessing the impact of surgical techniques on ear function post-CI.