Speech discrimination scores of postlingually deaf adults implanted with the Combi 40 cochlear implant.

The aim of the study was to assess the speech discrimination ability of postlingually deaf adults implanted with the Combi 40 cochlear implant and to compare the results with the postoperative data published for other devices. The postoperative open and closed set speech perception performance of 21 consecutive patients was tested using a standardized test battery comprising a number, monosyllable, sentence, consonant and vowel discrimination test as well as a rhyme test in the sound only condition. Mean values achieved for each test 1, 6 and 12 months after "switch on" were evaluated. The results demonstrate that all patients have a substantial benefit from their implant and show a continuous improvement in their speech perception abilities with increased device experience. The mean percentages of correct answers after 12 months were 93.4 for numbers, 44.6 for monosyllables, 78.5 for sentences, 67.6 for the rhyme test, 59.8 for vowel, and 67.3 for consonant discrimination. Preoperatively, the mean discrimination score for monosyllables was 0%. The speech discrimination scores of our patients were similar or higher than described for similar patient groups implanted with other devices. The high stimulation rate of the implant system using the continuous interleaved speech processing strategy as well as a deep atraumatic electrode insertion into the apicalmost regions of the scala tympani may be the reason for good performance.

Speech perception performance in prelingually deaf children with cochlear implants.

The goals of this study were to report on mean values of speech perception performance in prelingually deaf children implanted with a Combi 40/40 + cochlear implant. A total of 31 patients were included in the study. The time span ranged over 3 years, during which time the Evaluation of Auditory Responses to Speech (EARS) test battery was used with the children. The EARS battery contains four measures of closed-set speech perception and three open-set tests. The mean test results exhibited steady improvement on all parts of the EARS test battery, even up to 3 years post-implantation. The preoperative scores for the Listening Progress Profile (LiP) were 4%, rising to 93% at 36 months post-implantation. Results for the open-set testing measures were most encouraging, with some children reaching fairly high levels of speech perception, receiving scores as high as 100%, by the 36-month evaluation. The congenitally and prelingually deaf children in our study showed continuous improvement in both closed and open set speech perception following cochlear implantation, although variability in individual performance among the children was noted.

Fixation of the electrode array with bone paté in cochlear implant surgery.

The aims of this study are to report on our experiences using a bone paté (a mixture of bone dust and fibrin glue) fixation technique of the Combi 40/Combi 40+ electrode array during cochlear implant surgery. A retrospective study involving 57 patients implanted with Combi 40/Combi 40+ cochlear implants over 31 months fixated with bone paté was performed, utilizing our electrical fitting data as well as re-operation and X-ray findings. We found no signs of electrode retraction in any of the 57 patients. Electrical fitting data showed no reduction in the number of active channels between the first and last times patients were evaluated (a period of 4-31 months). Furthermore, a comparison of X-rays performed within the first week following cochlear implant surgery and again 7-27 months later showed no signs of electrode retraction in 10 patients. Three patients who required re-operations after implantation allowed us the opportunity to examine the effectiveness of the bone paté fixation and revealed new bone growth with the electrode fixed in place. Histological examinations of the newly built bone showed laminar and compact bone structures. The use of bone paté was thus found to be a suitable method of electrode fixation in cochlear implant surgery. Compared with other fixation methods, it is inexpensive and uses no foreign materials.

Perimodiolar electrodes in cochlear implant surgery.

Perimodiolar-positioned cochlear implant electrodes have been developed in order to bring the electrode contacts as close as possible to the spiral ganglion cells, which are the target of electrostimulation. This results in lower electrical thresholds, higher dynamic ranges and less channel interaction when compared with normal implant electrodes which are usually located peripherally within the scala tympani. In this study we evaluated 4 different types of perimodiolar electrode: the Clarion Preformed electrode, the Clarion Preformed electrode with positioner, the Nucleus Contour electrode and the Med-El Perimodiolar Combi 40 electrode. These devices require different approaches to achieve a perimodiolar electrode position. The electrodes were inserted in fresh human temporal bones. After processing these bones with the electrodes in situ by employing a sawing, grinding and polishing technique, the inner ear structures as well as the electrode positions could be evaluated in detail. All electrode types studied had a more or less perimodiolar position; however, each type produced a certain amount of trauma to cochlear structures which is discussed in relation to mechanical properties. Further human temporal bone studies with improved perimodiolar cochlear implant electrodes are necessary in order to find an optimized type of electrode.