The multi-channel cochlear implant codes sounds on the bases of rate and place pitch. Experimental studies on animals and patients have shown it is difficult for electrical stimulation to code rate pitch above about 200-400 pulses/second. Therefore to convey as much information about speech as possible it is necessary to produce multi-channel stimulation or place pitch so that the important frequency cues in vowels and consonants can be perceived by the patient.

To determine for the effect of age (late versus early age) on the cochlear implant outcomes; in terms of language development, auditory skills, speech perception, and production outcomes).67 children were included in the study out of 93 implanted cases in the study period. Children were classified into 2 groups according to age at time of implantation. Group 1 contained 43 children who were implanted before the age of 5 years. Group 2 contained 24 children who were implanted after the age of 5 years. All children were evaluated pre-operatively and at 3, 6, 12, 24 months device experience using the language screening test, Standardized Arabic Language test, Listening Progress Profile (LiP Test), the Monosyllabic-Trochee-polysyllabic Test (MTP), and the meaningful Auditory Integration Scale (MAIS) Test. Charts with incomplete data were excluded.Only 67 children had complete data out of 93 patients. The mean age (in months) for Group 1 was (43.37 ± 8.63) and for Group 2 was (70.38 ± 9.97) at time of implantation. Significantly higher mean values were detected for Group 2 in comparison to Group 1 in the pre-operative period. No significant difference was detected after 2 years evaluation using the test battery for language development and auditory skills.Children who were implanted under the 5 years of age had a better outcome in the form of better auditory skills, speech perception, and language production. Limited resources and the absence of a national hearing screening program in Saudi Arabia result in the late presentation of children for evaluation and intervention of hearing problem; this late intervention reduces the benefits the late – implanted children derive from cochlear implantation.

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 Cochlear/Melbourne array.Background: Advantages to be expected of a perimodiolar electrode array include 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 fur position of the electrode array as well as insertion-related intracochlear damage.Results: All perimodiolar electrode arrays were inserted deeper and showed trajectories that were generally closer to the modiolus compared with the standard electrode array. However, although the precurved array designs did not show significant insertion trauma, the method of insertion needed improvement. After insertion of the straight electrode array with positioner, signs of severe insertion trauma in the majority of implanted cochleas were found.Conclusions: Although it was possible to position the electrode arrays close to the modiolus, none of the three perimodiolar designs investigated fulfilled satisfactorily all three criteria of being easy, safe, and atraumatic to implant.

Eighty-eight children who underwent cochlear implantation at the University of Melbourne Cochlear Implant Clinic are reviewed. The aetiology of the hearing loss is classified and is compared to their best level of speech perception performance. The group whose hearing loss was not congenital in origin performed better than those who were congenital in origin. Of those whose hearing loss was congenital in nature those with rubella appeared to perform best.

On January 19, 1993, during his sixth year of multichannel cochlear implant use, a Nucleus 22-channel patient suffered complete cardiac arrest, requiring cardiopulmonary resusci­ talion and repealed defibrillation. The maximum number of joules available for defibrillation (500) were required to restore his cardiac function. The patient suffered no other cardiac arrests during his recovery and returned to work on a half-day schedule on March 1, 1993. Complaining that he needed a new program (map), he returned to his implant center for reprogramming of his mini speech processor on April 29, 1993. As displayed in Table 1, the minor changes measured in his electrical thresholds and comfort levels were no more than those frequently observed at reprogramming sessions. When he received the new MPeak map, his cochlear implant perfonnance returned to previous levels. His audilory perfonnance scores before and after defibrillation are remark­ ably similar, as detailed in Table 2. He has continued 10 use his device without incident, and his electrical levels have re­ mained stable, as shown in Table 3.

This is a publisher’s version of an article published in The Australian Journal of Otolaryngology 1995. This version is reproduced with permission from Australian Society of Otolaryngology Head and Neck Surgery.

of China. BecauseMandarin Chineseis a tonal language, testing thepatient's ability to distinguish among four tones is ofparamountimportance. This paperevaluates the efficacy of the Nucleus 22-Channel Mini System for Mandarin Chinese by comparing the postoperative tone perception test results with the results of the closed-set monosyllable, trochee, and spondee (MTS) test, and the open-set phonetically balanced (PB) word and sentence comprehension tests, which also incorporate tonal features, for eight Mandarin-speaking postlingually deaf patients implanted with this device. Except for one patient, the data clearly indicate that patients who had increased scores on tone perception after implantation also had improvements on other test batteries. Results also substantiate our previous observation that the Nucleus 22-channel cochlear implant enables profoundly and totally deaf patients to distinguish four separate tones in Mandarin Chinese. This would seem to support our earlier speculation that the acoustic cues of fundamental frequency of the four Mandarin tones are extracted by the Multipeak coding strategy of the 22-channel device and transferred to the cochlea, where they are perceived as rate pitch.

The histopathologic consequence of removing and reimplanting intracochlear electrode arrays on residual auditory nerve fibers is an important issue when evaluating the safety of cochlear prostheses. The authors have examined this issue by implanting multichannel intracochlear electrodes in macaque monkeys. Macaques were selected because of the similarity of the surgical technique used to insert electrodes into the cochlea compared to that in humans, in particular the ability to insert the arrays into the upper basal turn. Five macaques were bilaterally implanted with the Melbourne/Cochlear banded electrode array. Following a minimum implant period of 5 months, the electrode array on one side of each animal was removed and another immediately implanted. The animals were sacrificed a minimum of 5 months following the reinsertion procedure, and the cochleas prepared for histopathologic analysis. Long-term implantation of the electrode resulted in a relatively mild tissue response within the cochlea. Results also showed that inner and outer hair cell survival, although significantly reduced adjacent to the array, was normal in 8 of the 10 cochleas apicalward. Moreover, the electrode reinsertion procedure did not appear to adversely affect this apical hair cell population. Significant new bone formation was frequently observed in both control and reimplanted cochleas close to the electrode fenestration site and was associated with trauma to the endosteum and/or the introduction of bone chips into the cochlea at the time of surgery. Electrode insertion trauma, involving the osseous spiral lamina or basilar membrane, was more commonly observed in reimplanted cochleas. This damage was usually restricted to the lower basal turn and resulted in a more extensive ganglion cell loss. Finally, in a number of cochleas part of the electrode array was located within the scala media or scala vestibuli. These electrodes did not appear to evoke a more extensive tissue response or result in more extensive neural degeneration compared with electrodes located within the scala tympani. In conclusion, the present study has shown that the reimplantation of a multichannel scala, tympani electrode array can be achieved with minimal damage to the majority of cochlear structures. Increased insertion trauma, resulting in new bone formation and spiral ganglion cell loss, can occur in the lower basal turn in cases where the electrode entry point is difficult to identify due to proliferation of granulation and fibrous tissue.

This is a publisher’s version of an article published in The Australian Journal of Otolaryngology 1995. This version is reproduced with permission from Australian Society of Otolaryngology Head and Neck Surgery.