Bilateral EABR stimulating mode testing bilateral CI patients refecting binaural integration:a preliminary study

To analyze binaural integration, we used a new stimulation mode of the electrically evoked auditory brainstem response (EABR), to reflect bilaterally implanted cochlear function.

EABR was tested using the following procedure: First, both ears were evaluated separately, with the contralateral speech processor closed (C), followed by another measurement with both processors open (O). Subsequently, the eV latencies and amplitudes were assessed. The Speech, Spatial, and Qualities of Hearing Scale (SSQ), Categories of auditory performance (CAP) and speech intelligibility rating (SIR) scores were used to assess binaural hearing ability subjectively.

Fifteen subjects with bilateral CI from 1997 to 2018 were recruited, each diagnosed with severe to profound hearing loss.

All SSQ scores, except for one, were greater than six (the exception scored 1.3/0.8/1.0). All CAP/SIR scores except one were greater than 6/4 (the exception scored 0/1). All patients exhibited good quality EABR measurements. The open contralateral processor significantly reduced the eV latency while enhancing the eV amplitude compared to monaural stimulation. The objective EABR results were consistent with subjective speech perception and auditory ability assessed using the SSQ scale.

The EABR accurately reflected auditory pathway maturation and development after CI; thus, reflecting accordance with subjective speech and hearing performances. Furthermore, bilateral CI facilitates binaural integration and auditory brainstem plasticity.