Accuracy of high-resolution computed tomography in cochlear implantation

Multichannel cochlear implants are a proven method for the auditory rehabilitation of individuals who have severe-to-profound sensorineural hearing loss. These devices typically require insertion into the scala tympani of the cochlea to provide auditory stimulations. A patent scala provides the best chance for an adequate insertion of the electrode array. Preoperative high-resolution computed tomography imaging has traditionally been used to determine the patency of the scala tympani. Its ability to accurately predict the patency of the cochlea has been questioned in several retrospective studies. A prospective study was undertaken in 28 consecutive individuals undergoing cochlear implant surgery to compare the findings on high-resolution computed tomography with the surgical findings in an attempt to determine high-resolution computed tomography's accuracy. Cochlear obstruction caused by ossification was accurately predicted in six of six individuals but overestimated in the round window region in three individuals. High-resolution computed tomography accurately predicted patent cochleas in 19 individuals. No false-negative results were encountered. In this study sensitivity of high-resolution computed tomography was 100%, and specificity was 86%. High-resolution computed tomography appears to be more helpful than previously reported for determining cochlear patency.