Hearing-impaired infants with normal otoacoustic emissions

Background: Most congenital deafness is caused by cochlear lesions. Auditory brainstem response and otoacoustic emissions were expected to be abnormal in these patients. However, we present four hearing-impaired infants who had normal otoacoustic emissions. Methods: Over a period of 18 months, we identified four hearing-impaired infants with normal otoacoustic emissions and an absent auditory brainstem response. A series of examinations, including a behavioral audiometric test, acoustic reflex, evaluation of mental development, magnetic resonance imaging (MRI), evoked potential test of peripheral sensation and vision, and a hearing aid evaluation, were done. Results: Behavioral audiometric testing showed profound hearing loss in one patient, severe loss in two, and moderate loss in one. The pure tone threshold of the patient with moderate impairment appeared to have changed over the past 6 months. All four patients showed no acoustic reflex up to the level of 110 dB HL pure tone stimulation. No patients had mental retardation. MRI showed no abnormalities. One patient had a deficit of the visual pathway, one had a deficit of the somatosensory pathway, and one had both of these deficits. Amplification with hearing aids was applied without an improvement in hearing in three patients. Thus, auditory neuropathy might account for these patients' hearing impairment. Conclusion: Using auditory brainstem response and otoacoustic emissions, we are able to identify patients with disorders of retrocochlear function, in which the function of the cochlear outer hair cells is preserved. In patients with auditory neuropathy, the severity of hearing loss varies, from moderate to profound, or fluctuated. Their intelligence is normal essentially. Some patients are found to have accompanying peripheral neuropathy. Amplification with hearing aids is shown to be with little benefit. We suggest that total communication, instead of auditory/verbal training, is the method of choice for their rehabilitation.