Clinical, surgical, and electrical factors impacting residual hearing in cochlear implant surgery.

CONCLUSIONS: This study recommends using soft surgical principal and round window insertion to protect residual hearing with favorable anatomical exposure. Further studies are needed to evaluate the impact of the electrical stimulation on the organ of corti and hearing.

OBJECTIVE: The objective of this study is to analyze various factors that impact on preservation of residual hearing post-implantation.

METHODS: A retrospective study was performed to analyze loss of residual hearing in a cohort of 225 patients implanted in a large academic center. Sixty-four patients met the inclusion criteria. The impact of age at implantation, gender, etiology of hearing loss, cochleostomy vs round window insertion, partial vs full insertion, and effect of initial stimulation were analyzed using appropriate statistical analysis.

RESULTS: The overall hearing preservation rate for all implanted patients was 64%. Loss of residual hearing was significantly more observed in cases of cochleostomy and/or non-soft surgical techniques. No correlation was observed with age at implantation, gender, side of implant, device manufacturer, and presence of pre-lingual deafness vs post-lingual, full or partial electrode insertion. In addition, there was a small but significant decrease in hearing between pre-stimulation and post-stimulation audiograms at 6000 Hz.