Added Value of MDCT in Cochlear Parameters Assessment in Patients with Sensory Neural Hearing Loss Candidates for Cochlear Implantation

Abstract

The aim of this study is to detect the variations in cochlear size which may help in selection of the best cochlear implant electrode length and may also influence the insertion depth angles of the electrode arrays. To achieve this goal, 40 patients (21 females and 19 male) were included, their age ranged from 4 to 57 years (mean 24.63±17.30 years), pre- and post-operative non-contrast CT examination of the petrous bone was performed. It showed that, the cochlear distance (diameter A) ranged between 7.10 – 10.10mm (mean 8.53 ± 0.56mm) ,The cochlear duct length ranged between 25.50 – 38.0mm (mean 31.45 ± 2.33mm), postoperative, insertion depth angles ranged between 405 to 500o (mean 450.17±36.77), for advanced bionics, 211.0 – 420.0o (mean 367.56 ± 71.81o) for cochlear nucleus, 371.0 – 520.0o (mean 456.14 ± 61.33o) for Flex 28, and 475.0 – 598.0o (mean 513.06 ± 31.76 o) for Med-El standard electrode, a non-significant correlation was found between the insertion depth angles and the cochlear distance. A statistically significant positive correlation was found between the insertion depth angle and length of the electrode array. Therefore, it is concluded that assessing the cochlear parameters helps to choose the optimal electrode to provide proper cochlear coverage while avoiding insertional trauma.