Fitting parameters in children with cochlear implants and severe additional disabilities

The aim of this study was to investigate whether the fitting data of children with Cochlear implants (CI) and severe additional disabilities (CAD) differ compared to children with CI but without additional disabilities (CnonAD).

In this retrospective analysis, 76 CI cases (fitted ears) from CAD were included and matched with 76 cases from CnonAD. The subjective set values, such as pulse width (PW), threshold (T) and most comfortable (MC) levels were recorded. Additionally, the response threshold values by means of aided soundfield threshold (AST), the values of the intracochlear electrode impedances, the eCAP thresholds and the daily wearing time by using data logging were recorded and analysed.

The T and MC levels for the Medel implants were significantly lower in the sample than in the control group. A similar trend was evident for Cochlear^® implants. The sample showed a positive correlation between the eCAP thresholds and the T level and MC level in case of the Cochlear implants. The CAD group showed a significantly higher aided soundfield threshold. In contrast to the CnonAD (0%), there was a total of 18% in the CAD with a reduced daily wearing time. When these were excluded, eCAP thresholds were significantly higher in the CAD group. In addition, there was a trend for eCAP thresholds to be higher if the contralateral ear was not also fitted with a CI.

The significantly higher eCAPs in CAD may be explained by different neural survival but also by different fittings and MC levels. The audiuologist's subjectivity must be considered as a potential bias but also as potentially valuable input variable contributing to the variance in the fitting parameters and outcomes. Better fitting of T and MC levels focusing on behavioural and developmental responses may lead to a longer wearing time. To support the audiologist and the fitting process, it is necessary to interpret the response thresholds in the aided soundfield threshold against the background of the medical diagnosis and observations from everyday life should be considered. To ensure optimal development of CAD children according to their individual abilities, a multi-professional, family-centred intervention programme including videoanalyses should be implemented at an early stage, ideally from the decision process for a cochlear implant.