Int. Adv. Otol. 2010; 6(2); 125-130

Preservation of low-frequency residual hearing after cochlear implantation. Is soft surgery effective?
Veronique J.O. Verhaegen, Ad F.M. Snik, Andy J. Beynon, A. Rens Leeuw, Emmanuel A.M. Mylanus
Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands

Objectives: To evaluate the preservation of residual hearing after cochlear implantation and to analyze the effect of soft surgery.

Study Design: Retrospective.

Methods: 58 patients implanted with a Nucleus Contour cochlear implant electrode were included. Their preoperative hearing threshold was 90 dB or better at 250 Hz and 110 dB or better at 500 Hz. Patients with partial and/or any aberrant insertion of the electrode array, hearing loss due to meningitis, osteogenesis imperfecta and malformations of the cochlea or labyrinth were excluded. Pre- and postoperative thresholds were compared. The change in hearing threshold after implantation in the nonimplanted ear was subtracted from the change in hearing threshold in the implanted ear, which was defined as the ‘corrected threshold difference'. This ‘corrected threshold difference' was compared between two different implantation techniques: classic implantation versus soft surgery implantation.

Results: Median corrected threshold differences for the lower frequencies were 25 dB at 250 Hz and 20 dB at 500 Hz. In the soft surgery group, these differences were 10 dB and 7.5 dB respectively.

Conclusions: The classic surgery as well as the soft surgery implantation technique is good for preservation of residual hearing, however, there is a trend towards a better preservation of residual hearing according to the soft surgery protocol.