Preservation of Residual Hearing after Cochlear Implant Using SMA

Is residual hearing preserved after cochlear implantation with the suprameatal approach (SMA) technique? And, is there an alternative analysis to document the conservation of hearing more accurately?

Background: The SMA is the most frequently used implantation technique for cochlear implantation. The SMA has received both criticism and praise since its introduction in 1999, but the question of its appropriateness for preserving residual hearing has never been addressed.

Study design: Retrospective chart review.

Setting: Department of Otorhinolaryngology-Head and Neck Surgery, Academic Medical Center, University of Amsterdam, The Netherlands; Department of Otolaryngology-Head and Neck Surgery, Maastricht University Medical Center, The Netherlands; and Department of Otolaryngology-Head and Neck Surgery, University Medical Center Utrecht, University of Utrecht, The Netherlands.

Synopsis: The review included 109 severely to profoundly hearing-impaired cochlear recipients who had some measurable hearing preoperatively. The pre- and postoperative pure-time thresholds were analyzed by three different analyses to observe the degree of hearing preservation. Single-subject results showed a complete conservation of residual hearing in 24.7 percent of patients and partial conservation in 70.6 percent of patients. Group-subject results demonstrated that the median postoperative pure tone average (PTA) was 11.7 dB worse than the preoperative PTA. For individual frequencies, the median deteriorations were 15, 20, 10 and 5 dB at 250, 500, 1,000 and 2,000 Hz, respectively. Stratification for the absence of postoperative hearing thresholds showed a conservation of measurable postoperative hearing levels in 17.4 percent of all study patients.

Bottom line: Complete preservation of residual hearing is possible in a limited number of patients using the SMA for cochlear implantation. For a reliable analysis of the audiometric effects of cochlear implant surgery, the authors said it is important to take into account the ceiling effects, using different calculation methods to estimate the accurate deterioration of hearing thresholds.

Citation: Postelmans JTF, van Spronsen E, Grolman W, et al. An evaluation of preservation of residual hearing using the suprameatal approach for cochlear implantation: Can this implantation technique be used for preservation of residual hearing? Laryngoscope. 2011;121(8):1794-1799.

-Reviewed by Sue Pondrom