Cochlear size variation among the Argentinian population

Cochlear size, shape and the anatomy vary a lot among the human population. Cochlear size is a clinically useful parameter to determine the suitable cochlear implant electrode length. Objective is to assess the cochlear size and shape variation among the Argentine population.

Computer Tomography (CT) scans of 247 ears were assessed for the cochlear parameters including basal turn diameter (A-value) and width (B-value) and the cochlear height in the mid-modiolar section (H-value) using OTOPLAN® version 4.0. Shape of cochlear basal turn was determined by the ratio between B- and A-values. Cochlear Duct Length (CDL) was estimated from the A-, and B-values.

The A-value was found to vary between 6.7 mm and 10.1 mm with a mean value of 8.7 ± 0.61 mm and the B-value was found to vary between 4.5 mm and 8.1 mm with a mean value of 6.4 ± 0.57 mm. The cochlear height as measured in the axial view from the mid-modiolar section was 3.78 ± 0.57 mm. Shape of the cochlear basal turn as determined by the ratio between B- and A-values showed 41 out of 248 ears (16.5%) have more of a round shaped basal turn with the ratio of ≥0.75 leaving the remaining 207 ears (83.5%) with more of an elliptical shaped basal turn. CDL was found to vary between 24.5 mm and 41.2 mm with a median value of 33.6 mm.

Argentine population appears to have slightly smaller cochlear size compared to population from other countries as reported in literature.