Bilaterally preserved otoacoustic emissions in four children with profound idiopathic unilateral sensorineural hearing loss.

Severe to profound unilateral sensorineural hearing loss of the left ear was discovered by screening in four healthy children without any family history of hearing loss. Three of the children were four years old and one child was seven years old at the time of discovery. The PTA0.5-2 was 66-75 dB HL for three of the children and one child was without any hearing reactions on the affected ear. The hearing of the right ear was normal in all four cases. The hearing thresholds have been stable during an observation period of 3-12 years. No certain auditory-evoked brainstem responses were recorded with stimulation of the affected ear. Electronystagmography was normal in all cases and magnetic resonance imaging gave no explanation of the hearing loss. Repeated recordings of the transiently evoked otoacoustic emissions (TEOAE) have shown clear bilateral responses using different instrumentation systems. Recently the hearing levels were unchanged and the TEOAE responses of the affected ears were 6.7-19.9 dB SPL (waveform reproducibility: 88-98 per cent) recorded on the ILO88 OAE Analyser (stimulus: 82.2-83.4 dB peak). The collected results suggest that the children suffer from a similar disorder with a unilateral affection of the cochlea, involving the inner hair cells and/or the first neuron. The TEOAE recordings indicate substantially preserved outer hair cell function independent of the profound hearing loss.