Delayed loss of residual hearing in Clarion cochlear implant users

Hearing threshold has been measured in a group of patients following cochlear implantation with a Clarion device for the last eight years. The patients had received either a pre-curved carrier or the Hi-Focus I plus Electrode Positioner System (EPS). The assessment was carried out within the first post-operative week as well as at a later stage, between six and 87 months, post-operatively. Residual hearing thresholds were still measurable early after surgery in 24.5 per cent of the patients, without differences between the two different Clarion models. However, the number of subjects with measurable hearing dropped to 16.3 per cent as observed when hearing was measured at a later stage, with an equal distribution between the two groups of patients. From this study it has been possible to observe that only a limited number of patients maintain residual hearing after Clarion cochlear implantation, and that this tends to decrease further over time. Nevertheless, the performance of these patients for speech tests did not appear to be affected by deterioration of the pure-tone auditory threshold.