Utility of MRIs in adult cochlear implant evaluations.

Objectives: To determine the prevalence of MRI abnormalities in adults undergoing cochlear implantation and to correlate abnormalities to audiology data.

Study Design: Case series.

Setting: Academic medical center.

Methods: Adult patients (>18 yr old) undergoing cochlear implant evaluation from January 2008 to December 2012 were identified based on CPT code search. Demographics, preoperative MRI findings, operative findings, and audiometric data were collected.

Results: The study included 188 patients. Seventeen (9%) patients had significant otic capsule or vestibulocochlear nerve pathologies: 5 vestibular schwannomas, 4 enlarged vestibular aqueducts, 2 hypoplastic cochlear nerves, 2 labyrinthitis ossificans, 1 cochlear aplasia, 1 posterior semicircular canal malformation, 1 calcified meningioma, and 1 cholesterol granuloma. MRI results were normal (65%) or with findings not directly related to hearing loss (incidental findings, 25%) in the remaining patients. Mean pure tone average (PTA) differences (between the implanted and contralateral ear) did not significantly vary between normal-incidental and abnormal MRI scans (-6.6 dB versus -6.7 dB, p = 0.99) nor did speech discrimination scores (SDS) scores (8.5% versus 8.4%, p = 0.99). No significant difference was found in HINT scores for patients with a normal versus an abnormal MRI (19% versus 16,%, p = 0.62).

Conclusion: Although the majority of precochlear implantation MRIs were normal or demonstrated incidental findings, such as white matter changes, significant MRI findings affecting implantation site and patient counseling were found in almost 10% of patients. Audiogram findings did not correlate with abnormal findings on MRIs. Routine use of MRI in adult cochlear implant candidates may be warranted.