The intricate interrelationship of cochlear aperture and internal auditory canal diameter in pediatric normal petrous structures.

Purpose: The cochlear aperture and internal auditory canal dimensions play a pivotal role in cochlear nerve health, yet their normative data exhibit significant variability. This study seeks to establish definitive normative ranges for these dimensions and investigate their interrelationship in the context of normally developed pediatric temporal bones.

Methods: This prospective study included seventy-eight children under fifteen years, diagnosed with bilateral severe-to-profound sensorineural hearing loss and free from temporal bone deformities. Utilizing high-resolution computed tomography scans, we measured the diameters of the cochlear aperture at the mid-modiolar level and the internal auditory canal at the porus, midsection, and fundus. The associations between these dimensions were analyzed using Spearman's rank correlation and linear regression.

Results: The mean cochlear aperture diameter was 2.16 mm, while the internal auditory canal diameters at the porus, midsection, and fundus were 6.60 mm, 4.27 mm, and 3.88 mm, respectively. Significant positive correlations were observed between the cochlear aperture and internal auditory canal diameters at the midsection (rs = 0.246, p = 0.029) and fundus (rs = 0.338, p = 0.002), as well as the average internal auditory canal diameter (rs = 0.233, p = 0.039). Regression analysis indicated that the internal auditory canal diameter at the fundus explained 17.5 % of the variance in cochlear aperture diameter (β = 0.179, p < 0.001).

Conclusion: This study established normative ranges for cochlear aperture and internal auditory canal dimensions in children, addressing past variability. These findings support cochlear implant planning, with a regression model offering a noninvasive tool to estimate cochlear aperture size. We also identified a unique, significant correlation between the two, highlighting a shared developmental pathway.