A sample of 64 postlinguistically profoundly to totally deaf adult cochlear implant patients were tested without lipreading by means of the Central Institute for the Deaf (CID) sentence test 3 months postoperatively. Preoperative promontory stimulation results (thresholds, gap detection, and frequency discrimination), age, duration of profound deafness, cause of deafness, lipreading ability, postoperative intracochlear thresholds and dynamic ranges for electrical stimulation, depth of insertion of the electrode array into the scala tympani, and number of electrodes in use were considered as possible factors that might be related to the postoperative sentence scores. A multiple regression analysis with stepwise inclusion of independent variables indicated that good gap detection and frequency discrimination during preoperative promontory testing, larger numbers of electrodes in use, and greater dynamic ranges for intracochlear electrical stimulation were associated with better CID scores. The CID scores tended to decrease with longer periods of profound deafness.

Objective: To investigate whether the insertion depth of a cochlear implant array affects postoperative speech perception. Design: The subjects were 48 postlingually deaf adults who received either the Nucleus 22 or the Nucleus 24 cochlear implant with a straight array. A postoperative radiograph of the cochlear electrode was used to estimate insertion depth, as either the angle of the electrode tip (angle) or the intracochlear length of the electrode (length). Other estimates of insertion depth included the numbers of active electrodes and channels used by the speech processor. Electrode depth, together with the duration of deafness, hearing aid usage, pre-operative speech perception score and pre-operative pure-tone averages were independent variables in a forward stepwise multiple regression analysis, where the dependent variables were postoperative CNC words and CNC phonemes. Results: Duration of deafness and insertion depth (angle, insertion length or active electrodes) were the predictive variables for CNC words or CNC phonemes. Angle was the best ‘depth-related’ predictor of postoperative speech perception. An even clearer relationship was found between CUNY sentences in noise and angle, in a subset of 26 patients. Conclusion: Depth of electrode insertion affects postoperative speech perception.

The surgical complications for the first 153 multiple-channel cochlear implant operations carried out at the Medizinische Hochschule in Hannover and the first 100 operations at the University of Melbourne Clinic, The Royal Victorian Eye and Ear Hospital, are presented. In the Hannover experience the major complications were wound breakdown, wound infection, electrode tie erosion through the external auditory canal, electrode slippage, a persistent increase in tinnitus, and facial nerve stimulation. The incidence of wound breakdown requiring removal of the package was 0.6% in Hannover and 1.0% in Melbourne. The complications for the operation at both clinics were at acceptable levels. It was considered that wound breakdown requiring implant removal could be kept to a minimum by making a generous incision and suturing the flap without tension.

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Objective: This study was conducted to evaluate the insertion properties and intracochlear trajectories of three perimodiolar electrode array designs and to compare these designs with the standard CochlearlMelbourne array. Background: Advantages to be expected of a perimodiolar electrode array inclu<;le both a reduction in stimulus thresholds and an increase in dynamic range, resulting in a more localized stimulation pattern of the spiral ganglion cells, reduced power consumption, and, therefore, longer speech processor battery life. Methods: The test arrays were implanted into human temporal bones. Image analysis was performed on a radiograph taken after the insertion. The cochleas were then histologically processed with the electrode array in situ, and the resulting sections were subsequently assessed for position of the electrode array as well as insertion-related intracochlear damage. Intracochlear multichannel cochlear implants have successfully provided auditory information for profoundly deaf patients by electrically stimulating discrete populations of auditory nerve fibers via a scala tympani electrode array. The straight, yet flexible, tapered Melbourne/Cochlear electrode array can be safely implanted into the human cochlea. However, histologic and radiologic examination of implanted temporal bones showed that the electrode array is usually positioned along the outer wall of the scala tympani (1-5). The array is, therefore, some distance from the spiral ganglion cells in the Rosenthal canal and their peripheral processes. However,