[Evaluation of intra-operative EABR characteristics and rehabilitation effects of cochlear implantation in patients with internal auditory canal stenosis].

OBJECTIVE

To investigate the intra-operative electrical evoked auditory brain stem response (EABR) characteristics and the hearing and speech rehabilitation effects of cochlear implantation (CI) in patients with internal auditory canal stenosis (IACS).

METHOD

A retrospective study was performed on 16 patients with IACS (IACS group) matched with 16 implanted without IACS (control group), who received multi- channel CI because of pre-lingual sensorineural hearing loss. The integrity and functional status of the auditory pathway were assessed by EABR, recording waveforms, thresholds and dynamic ranges intra-operation before CI. Interviewed the implanted parents or teachers, asking them to rate the implanted hearing and speech ability according to Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR). Paired T test was performed to compare scores of CAP and SIR between before and 1 year after CI, while Spearman test was performed to compare correlation between EABR grades and post-operative CAP scores.

RESULT

Among the IACS group, 2 cases weren't recorded typical EABR waveforms and without auditory response 1 year after a successful CI. The EABR waveforms in the IACS group were poorer than that in the control group, their EABR thresholds higher than the control group, and their EABR dynamic ranges less than the control group. The hearing and speech rehabilitation after CI showed that the results of CAP and SIR values (3.47 +/- 1.09 and 1.62 +/- 0.50) scored significantly lower than the control group (5.06 +/- 0.79 and 2.59 +/- 0.58) (P < 0.05), but significantly increased compared with pre-operation. Intra-operative EABR grades and post-operative CAP scores showed significant correlation (r = 0.78 , P < 0.05).

CONCLUSION

Intra-operative EABR can accurately monitor the integrity and functional status of the auditory pathway, be of important clinical value in predicting whether patients can acquire auditory responses with the aid of CI. CI can help patients with IACS to improve the ability of hearing and speech with EABR to screen out compatible implanted.