Objective: To examine the outcome of cochlear implantation in children with auditory neuropathy (AN) and cochlear nerve deficiency (Group A). Results are compared with a cohort of children with AN and normal cochlear nerves (Group B).
Study design: Retrospective cohort study.
Setting: The Sydney Cochlear Implant Centre and the Children's Hospital at Westmead.
Patients: Children younger than 15 years with bilateral profound sensorineural hearing loss and the diagnosis of AN confirmed on electrophysiologic testing. All children underwent cochlear implantation with Nucleus 24 cochlear implants from 1997 to 2006.
Interventions: Magnetic resonance imaging was examined for deficiency of the vestibulocochlear nerve. Brain and inner ear abnormalities were recorded. Cochlear implant outcomes and demographic variables were compared.
Main outcome measures: Melbourne speech perception score (MSPS) at 1 year and implant evoked electric auditory brainstem response (EABR).
Results: Group A performed significantly worse on both parameters than Group B. In Group A, median MSPS was 1, compared with a median score of 4 in Group B (z = -3.010; p = 0.003). EABR was abnormal in 13 of 15 (87%) children in Group A, compared with 9 of 39 (23%) in Group B. Children in both groups with abnormal EABR had significantly worse MSPS (z = -2.780; p = 0.005). Fourteen of 15 children with cochlear nerve deficiency had associated inner ear abnormalities.
Conclusion: Children with AN can have associated cochlear nerve deficiency. These patients have worse speech perception scores at 1 year post cochlear implantation, higher rates of abnormal EABR, and more associated inner ear abnormalities than children with AN and normal cochlear nerves.