Evidence-based approach for making cochlear implant recommendations for infants with residual hearing

The aim of this study was to develop guidelines, based on the unaided pure-tone audiogram, for recommending a cochlear implant (CI) for infants and young children with residual hearing. As awareness of the benefits of early implantation increases and age at diagnosis decreases, an increasing number of infants are presenting for consideration of implantation with significant residual hearing in one or both ears. Determining the likelihood that these infants will have an improved speech and language outcome if they receive a CI is a challenge.

Subjects were 142 hearing impaired children (ages 4.6 to 16.2 yrs) with unaided three-frequency pure-tone average (PTA; at 500, 1000, and 2000 Hz) ranging from 28 to 125 dB HL: 62 used conventional amplification (analog or digital hearing aids [HAs]) and the remaining 80 used a Nucleus 24 (N24) or Freedom CI. Open-set monosyllabic word (Phonetically Balanced Kindergarten or Consonant-Nucleus-Consonant words) and sentence (Bamford-Kowal-Bench sentences) testing was administered audition alone to both groups of children.

Comparison of means for sentence testing showed that the children using CIs performed significantly better than their peers with profound hearing loss (PTA >90 dB HL) using HAs and not significantly differently to those with severe (PTA 66 to 90 dB HL) or moderate (PTA <66 dB HL) hearing loss. Comparison of means for monosyllabic word testing showed that the children using CIs performed significantly better than their peers with severe and profound hearing loss and not significantly differently to those with moderate hearing loss. Regression analysis was used to determine the equivalent unaided PTA values that corresponded to the median and first quartile scores for the children using CIs on speech perception testing. For open-set words, scored for phonemes correct, the equivalent unaided PTAs were 46 and 56 dB HL, respectively. For sentence testing, the equivalent unaided PTAs were 63 and 72 dB HL, respectively.

Results suggest that recommendation for implantation can be made confidently for children presenting with bilateral profound hearing loss. For children with unaided PTA hearing levels in the range of 75 to 90 dB HL, a recommendation for implantation can also be made, provided that a 75% chance of improvement in hearing outcome is an acceptable level of benefit to the family and clinician. Children presenting with PTA hearing levels better than 75 dB HL should be encouraged to continue with binaural HA use.