Insertion trauma caused by periomodiolar electrodes occurs to an acceptable degree. Refinement of electrodes based on mechanisms of trauma may be able to further reduce damage.

A new generation of cochlear implant electrodes has been designed to position the stimulating contacts close to the modiolus in order to reduce power consumption and increase stimulation selectivity. The purpose of this study was to assess electrode position in the cochlea for three recently designed electrodes. Fifteen cadaveric temporal bones were implanted with one of three perimodiolar electrode arrays: Nucleus Contour; Med-El Combi40+ PM (developmental version); and Clarion HiFocus II. Image-enhanced videofluoroscopy and computer morphometrics were used to assess stimulating contact position relative to the modiolus. The mean distance (+/- 1 standard deviation) to the modiolus for all electrode contacts was 0.33 (+/-0.24), 0.30 (+/-0.27) and 0.16 mm (+/-0.19) for the Contour, Combi40+ PM and HiFocus II arrays, respectively. In addition, dynamic videofluoroscopy was used to correlate device-specific insertion characteristics with contact-to-modiolus distance. All three devices were successful in terms of locating electrode contacts very close to the modiolar wall.

Narrow ABG at lower frequencies suggested absence of OD. Wide ABG at higher frequencies suggested presence of OD. Simple tympanoplasty can be done to patients with a small chance of OD as assessed by pure-tone audiometry, whereas a mandatory exploration of the ossicular chain with possible reconstruction was suggested on subjects with a high chance of OD. The presence of cholesteatoma warrants ossicular chain exploration.