Role of Cochlear Nerve Diameter as a Prognostic Indicator for Hearing Recovery in Older Adults with Idiopathic Sudden Sensorineural Hearing Loss

BACKGROUND: Idiopathic sudden sensorineural hearing loss is a disabling condition that lowers the quality of life specifically in older adults living alone. It is crucial to determine the outcome of the disease and to offer early treatment to prevent isolation caused by hearing impairment in this population. The objective of our study was to investigate whether the initial cochlear nerve thickness may predict the outcome of hearing recovery in older adults with idiopathic sudden sensorineural hearing loss. METHODS: The study population was composed of older adults that were referred with idiopathic sudden sensorineural hearing loss in 1 ear. Long-term audiological data of the cohort were analyzed according to Siegel’s criteria on hearing recovery and were grouped according to complete recovery or treatment failure. Cochlear nerve diameters of the diseased and safe ears of each group, measured on reformatted images on magnetic resonance imaging, at the fundus, in the mid-internal acoustic canal, and at the entry point into the Pons were compared in each group and between groups. RESULTS: Mean cochlear nerve diameter was significantly larger in the recovered older adults (1.11 ± 0.27 mm) than in the non-recovered adults (0.94 ± 0.21 mm) at the mid-internal acoustic canal (Student’s t-test, P < .05). Cochlear nerve thickness at mid-internal acoustic canal (≤0.8 mm) sensitivity for recovery failure was 89% and displayed an odds ratio 5.333, 95% CI (1.000-28.435). CONCLUSION: Cochlear nerve thickness in mid-internal acoustic canal in non-recovered older adults with idiopathic sudden sensorineural hearing loss is significantly thinner than the completely recovered group. Older adults with mid-internal acoustic canal cochlear nerve greatest diameter cutoff level of ≤0.8 mm are 5.33 times more exposed to recovery failure.