Audiological performance with cochlear reimplantation from analogue single-channel implants to digital multi-channel devices

Cochlear implantation has been performed for almost two decades at the Vien na University Hospital. Until 1994, single-channel implants were used (Ball -Electrode, SC6/2SC6, Vienna/Epoxy, Med-EI, Innsbruck, Austria). The develo pment of multi-channel devices (Combi 40/40+), which provide significantly improved speech recognition performance, led to the reimplantation of some patients who had previously received single-channel implants. It was of par ticular interest to find out if there was a deterioration of the central "l earning process" by the reimplantation from the analogue single-channel dev ice to the tonotopic pulsatile multi-channel stimulation. In this study, we attempted to demonstrate that single-channel implants have an impact on th e neural organisation of the auditory system. Two groups of post-lingually deaf adult patients were tested. Group A had previously received single-cha nnel implants and were reimplanted with the new Combi 40/40+ cochlear impla nt (Med-El, Innsbruck, Austria) in the same ear. Group B was implanted only with the Combi 40/40+. Six different speech recognition tests were subsequ ently performed on all patients, and the two groups performed similarly. Fu rthermore, it was discovered that group A obtained significant speech recog nition improvement (p<0.05) with monosyllabic words and number tests 1 mont h following reimplantation.