Results of cochlear implantation candidate patients by high resolution computed tomography and magnetic resonance imaging

Abstract

Objectives: To evaluate the effectiveness of high resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) for assessment of factors which would influence the type and success of surgery in patients undergoing cochlear implantation. Materials and methods: All patients underwent HRCT imaging while MRI was performed in 38 of them. MRI and HRCT images were evaluated for mastoid cell pneumatization, sigmoid sinus localization, aberrant vascular structures, congenital anomalies, cochlear stenosis, labyrinth ossification, infection, internal acoustic canal width, presence of vestibulo-cochlear nerve, semicircular canals, cerebellopontin area, and cochlear and vestibular aquaduct width. Results: Totally 49 patients (29 males and 20 females with a mean age of 12.3 years (1-61 years) were included. Various abnormalities or congenital anomalies were found in 35 patients by HRCT and MRI. We observed grade 1 mastoid cell pneumatization in 58 ears (59.3%), grade 2 in 23 (23.4%) and grade 3 in 17. Furthermore the position of sigmoid sinus (p<0.001) and mastoid width (p<0.001) were affected by mastoid cell ventilation. HRCT provides knowledge about mastoid and middle ear ventilation, cortical bone thickness, round window niche, perilymphatic-endolymphatic compartment and status of internal acoustic canal. Pathologies such as otosclerosis and Paget disease that involve otic capsule can be revealed by CT. MRI can provide views of intracochlear viscosity and cochlear opening, semicircular canals, cerebellopontin area, and vestibulocochlear nerve. Conclusions: HRCT and MRI provide information about the etiology of hearing loss, suitable side for cochlear implantation and detection of abnormalities or anatomic variations that may cause complications introperatively.