High Resolution Computed Tomography and Magnetic Resonance Imaging in the Preoperative Assessment for Cochlear Implantation Candidacy

Abstract
Background: High Resolution Computed Tomography (HRCT) and magnetic resonance imaging are regularly used for cochlear implant preoperative evaluation for the evaluation of inner ear malformations, surgical planning, and especially the imaging of the VIIIth nerve. In children, these imaging procedures are especially important due to the high incidence of inner ear malformations.
Aim of Work: To study the role of high resolution com-puted tomography and magnetic resonance imaging in clas-sifying 70 patients with profound deafness for possible absolute contraindications for surgery, relative contraindica-tions for surgery (difficult surgery) or easy surgery for cochlear implant.
Subjects and Methods: We performed a cross sectional descriptive study on 70 patients with profound SNHL for possible cochlear implantation surgery followed-up by Helwan University Teaching Hospitals between January 2016 and December 2017.
All patients were subjected to high resolution CT scan (64 mutlislice) and 3D T2 MRI of the temporal bone to delineate condition of the mastoid, vascular anomaly, internal auditory canal, cochlear nerve, size of the cochlea, status of the endo-and perilymphatic fluid, round window niche and variation of the facial nerve.
All Patients were Classified into: Absolute contraindica-tions to cochlear implant surgery, relative contraindications to cochlear implant surgery and their complicating factor in making surgical intervention with relative difficulty, otherwise easy surgical intervention is assumed.
Results: We studied a total of 70 patients with profound deafness planned for cochlear implantation surgery and our results showed 5.7% (n=4) of the study group would not benefit and cochlear implantation surgery is contraindicated for these patients as well as 41.4% (n=29) of the patients have had complicating criteria that possibly make surgical inter-vention difficult in comparison 52.9% (n=37) with anticipated straight forward surgical intervention which were statistically significant.
Conclusion: The correct classification of cochlear condi-tions and a clear description of such abnormalities by means of multislice CT and 3D MRI are determining factors in the surgical planning developed by the cochlear implantation team, with direct impact on the success of the surgical inter-vention. Thus the radiologist experienced in the evaluation of the temporal bone plays a major role in the course of this disorder.