A Case of Cochlear Nerve Deficiency Without Profound Sensorineural Hearing Loss

Objective: To describe a case of cochlear nerve deficiency ( CND) with unique otologic findings. Patient: A 6-year-old girl. Main Outcome Measures: Magnetic resonance imaging, pure tone audiometry, distortion product otoacoustic emissions, and auditory brainstem response. Results: The patient showed moderate sensorineural hearing impairment limited to high frequency in the right ear on pure tone audiometry. The auditory brainstem response was absent on the right; however, distortion product otoacoustic emissions were detected on both sides. The right cochlear nerve at the level of the fundus was absent on 3-dimensional constructive interference in steady state magnetic resonance imaging. Conclusion: Most cases of CND show deafness or profound hearing loss, but the patient in this case had only moderate hearing loss. This finding provides evidence that auditory thresholds are variable in patients with CND. Therefore, careful evaluation is needed in diagnosis of patients with hearing loss.