Implications of minimizing trauma during conventional cochlear implantation

Abstract

Objective: To describe the relationship between implantation-associated trauma and postoperative speech perception scores among adult and pediatric patients undergoing cochlear implantation using conventional length electrodes and minimally traumatic surgical techniques.

Study design: Retrospective chart review (2002-2010).

Setting: Tertiary academic referral center.

Patients: All subjects with significant preoperative low-frequency hearing (≤70 dB HL at 250 Hz) who underwent cochlear implantation with a newer generation implant electrode (Nucleus Contour Advance, Advanced Bionics HR90K [1J and Helix], and Med El Sonata standard H array) were reviewed.

Intervention(s): Preimplant and postimplant audiometric thresholds and speech recognition scores were recorded using the electronic medical record.

Main outcome measure(s): Postimplantation pure tone threshold shifts were used as a surrogate measure for extent of intracochlear injury and correlated with postoperative speech perception scores.

Results: : Between 2002 and 2010, 703 cochlear implant (CI) operations were performed. Data from 126 implants were included in the analysis. The mean preoperative low-frequency pure-tone average was 55.4 dB HL. Hearing preservation was observed in 55% of patients. Patients with hearing preservation were found to have significantly higher postoperative speech perception performance in the CI-only condition than those who lost all residual hearing.

Conclusion: Conservation of acoustic hearing after conventional length cochlear implantation is unpredictable but remains a realistic goal. The combination of improved technology and refined surgical technique may allow for conservation of some residual hearing in more than 50% of patients. Germane to the conventional length CI recipient with substantial hearing loss, minimizing trauma allows for improved speech perception in the electric condition. These findings support the use of minimally traumatic techniques in all CI recipients, even those destined for electric-only stimulation.

FIG. 1

Mean preoperative and postoperative speech perception scores (CNC, AzBio, and BKB-SIN) for the hearing preservation and nonhearing preservation groups. The filled and unfilled bars represent scores for the hearing preservation and nonhearing preservation subjects, respectively.

FIG. 2

Mean low-frequency postoperative threshold shift among patients within the hearing preservation group.