The effect of interdevice interval on speech perception performance among bilateral, pediatric cochlear implant recipients

Objectives/hypothesis: To determine if prolongation of the interdevice interval in children receiving bilateral cochlear implants adversely affects speech perception outcomes.

Study design: Retrospective chart review.

Methods: Retrospective review of our pediatric cochlear implant database was performed. Children who had undergone revision surgery or had less than 12 months listening experience with either the first or second implant were excluded. The interdevice interval, best Phonetically Balanced Kindergarten word lists (PBK) score from each ear, and demographic data about each patient were collected. A ratio of PBK was generated (PBK second side/PBK first side) to minimize potential confounding from other individual patient factors that affect speech outcomes.

Results: Two hundred forty children met the study criteria. Mean age at first cochlear implantation (CI) was 3.2 years (0.6-17.9), and the second was 6.6 years (0.8-22.4). Mean best PBK score from the first CI side was 83.8% (0-100), and the second was 67.5% (0-100) (P < .001). When the PBK ratio was plotted against interdevice interval, R(2) was 0.47 (P < .001). When analyzed for hearing stability, those with a progressive loss history demonstrated less influence of prolonged interdevice interval on performance. Multivariate analysis did not identify other factors influencing the ratio. A line of best fit for those with stable hearing loss suggested best outcomes were with an interdevice interval less than 3 to 4 years. Beyond 7 to 8 years, very few achieved useful speech recognition from the second CI.

Conclusions: Where possible, the second implant should be received within 3 to 4 years of the first to maximize outcome in those with stable, severe to profound sensorineural hearing loss.

Level of evidence: 4. Laryngoscope, 126:2389-2394, 2016.