Prediktivni faktory kochlearni implantace.

Abstract

The main theme of the thesis was a statistical evaluation of the influence of certain preoperative and postoperative factors on benefit of cochlear implantation. We have tried to verify a hypothesis that using specific factors registered both before and after surgery we can predict to a certain extent benefit of cochlear implantation. We were also interested how our correlations are set in the general literary context. Complex preoperative assessment of cochlear implant candidates and our selection criteria are described together with algorithm of choosing the "better" ear for surgery. The analysed group consisted of 39 patients and following features were evaluated: age in the time of surgery (in revision age in the time of the first surgery), number of possible revisions, sex, aetiology of deafness, length of deafness, type and category of deafness, used type of neuroprosthetic device, stimulation strategy used, number of channels. Influence of these features on benefit of implantation as assessed by Categories of Auditory Performance was looked for. Significant statistical correlation can be seen between continuous and interrupted thresholds (on frequency 250 Hz) in Bekesy audiometry (difference limen for intensity) during a promontory test. There was only a weak statistical influence of a length of deafness and number of active channels on a benefit. Also, there were very weak and insignificant correlations between UCL levels and age in time of surgery. We have tried to prove a postulate, that implantees with a shorter duration of deafness have a higher benefit than those with a longer time of hearing deprivation. The procedure was nevertheless successful only after some data filtration: there was evident, that patients implanted after a short duration of deafness (<5 years) are significantly better in benefit score that patients who were deaf for a long time (>15 years). There was no statistical influence of aetiology on benefit. But in our analysed group patients after meningitis were significantly worse in benefit score than implantees in the aetiologic group of a head trauma. This may be explained by a lower number of surviving ganglion cells after meningitis, but a more evident explanation is represented by the fact that in the group of postmeningitic deafness there was one patient with a bilateral complete obliteration of cochlea and very low score. In such a small number of patients this can have a strong impact on the final results. There was no influence of category of deafness in the benefit, but there were statistically significant differences between prelingually and postlingually deaf patients regarding results of implantation. Postlingually deaf implantees (especially those with a short time of sensoric deprivation ) were much better that prelingually deaf. But this finding is strongly influenced by the fact, that in the beginning of implantation programme a fair amount of prelingually deaf adults and adolescents were implanted - groups, which nowadays are looked on as the least favourable regarding benefit. According to cluster analysis, the adult candidate with the highest potential for neuroprosthesis is a postlingually deaf, with a short time of deafness duration. There is no influence of age at which the candidate was implanted. There is no influence of used strategy and number of channels on performance providing that non-standard methods were filtered out. Atypical strategies (as variable) or lower number of channels always represent some kind of problematic solution (obliterated cochlea, misinduced array etc.) and as such cannot be included into the statistical comparison.Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi