Defining and evaluating success in paediatric cochlear implantation--an exploratory study

This work is a preliminary study that sought to investigate and develop a method for defining and evaluating "success" in paediatric cochlear implantation (PCI) and to apply a process by which a clinical team could optimally achieve this aim.

A pilot group of 25 profoundly deaf children who received a unilateral cochlear implant from 1995 to 2008 was used to develop the process. The cases displayed features that are commonly encountered in PCI. Individual case records were examined retrospectively for adverse factors that might impact on the implantation outcome with particular reference to the probability and severity of impact of each factor. Case prognosis was then rated on a 1-4 basis (1: excellent, 2: good, 3: fair, 4: poor). The subsequent outcomes were assessed using standardised speech (GFW, DEAP), language (PLS-4; CELF) and vocabulary (PPVT; EVT) assessments. Auditory performance outcomes were assessed using a new Categories of Auditory Performance Index (CAPI) that incorporated criteria, testing and scoring aspects. Family issues were also evaluated. Case outcomes were rated 1-4 as above and the prognoses and outcomes were then compared.

Accurate prognostication was seen in 14 cases, 5 had better outcomes than expected and 6 obtained poorer results. "Success", where the outcome equalled or exceeded the prognosis, occurred in 19 (76%) of cases. The successful group contained some "limited gains" cases where the results were nonetheless in line with expectations and parental satisfaction. The detrimental effect of delayed implantation was evident; Connexin 26 (GJB2) mutation had little influence. Poor general medical condition and adverse family situations commonly produced poorer outcomes.

Success in PCI is achieved when the outcome matches or exceeds the pre-operative expectations of the well-counselled family, without adverse side effects. The assessments achieved a good success rate, but further research is required to clearly identify potential problems and a skilled team is needed to evaluate their risk to the PCI outcome. Unforseen events may also intervene. Currently, differing outcome evaluation techniques impede comparison of studies, particularly in the speech and hearing domains. Rationalisation of these is recommended to facilitate future research.