Residual hearing preservation after cochlear implantation via round window or cochleostomy approach.

OBJECTIVES/HYPOTHESIS The purpose of the study was to investigate whether cochlear implantation using the round window approach provided better preservation of residual hearing than the cochleostomy approach. STUDY DESIGN Case-control study. METHODS We designed a case-control study including 40 patients from a tertiary referral center who underwent cochlear implantation surgeries using devices from MED-EL Co., Innsbruck, Austria. Between November 2013 and July 2014, we prospectively enrolled 20 subjects for cochlear implantation surgery using the round window insertion approach. In addition, 20 age- and sex-matched control subjects from the database of cochlear implantees treated using the cochleostomy approach between January 2008 and October 2013 were retrospectively enrolled. The residual hearing of the operated ear was measured before and after surgery. The variables analyzed were the pure-tone average threshold at 250, 500, and 1,000 Hz and the residual hearing at frequencies of 250 to 8,000 Hz. The residual hearing was considered as preserved when the audiometric changes were <10 dB hearing loss for each variable. The audiological results of the two groups were compared. RESULTS No statistically significant difference in the preservation of residual hearing was found in the two groups (P > .05 for all of the variables). CONCLUSIONS The round window and cochleostomy approaches for cochlear implant surgery may preserve residual hearing at similar rates across a range of frequencies.