Novel intracochlear electrode positioner: effects on electrode position.

Spiral ganglion cells, located in the cochlear modiolus, are widely thought to be the neural elements stimulated by cochlear implants (CIs). Positioning CI electrodes adjacent to the modiolus may allow delivery of more focused, discrete fields of electrical stimulation, reducing both current requirements and the channel interaction associated with simultaneous stimulation. In order to provide greater consistency in positioning CI electrodes against the modiolus, Advanced Bionics Corporation has designed a silicone intracochlear positioner that is inserted alongside the electrode. Placed against the outer wall of the scala tympani, it directs the electrode array toward the modiolus. Five fresh-frozen temporal bones were studied to validate enhanced electrode placement. Electrode position was documented with image-enhanced digital fluoroscopy, and the distance to the modiolus was measured with computer-assisted morphometrics. The electrode positioner was highly effective in positioning the electrodes closer to the modiolus (p < .001).

Changes in stimulation levels over time in nucleus 22 cochlear implant users.

The purpose of this study was to evaluate changes that occur over time in the electrical stimulation levels of cochlear implant users. A retrospective review of program summaries for 26 postlingually deafened adult Nucleus cochlear implant users was completed. Program summaries were used to assess changes in electrical stimulation at threshold (T) and maximum comfort (C) levels. Comparisons were made at intervals including the subject's initial stimulation and 2-week, 3-month, 6-month, 1-year, and most recent programming sessions. Five patients had 5 years or more of implant use; 8 patients had 3 to 5 years or more of implant use; and the remainder had been using their implant for 2 to 3 years. No patient with less than 2 years of implant use was included. Results indicated that changes in stimulation levels occur gradually over time. Although the changes in stimulation levels from one programming session to the next were not significant, the changes in current requirements for both T and C levels were found to be significant when we compared the 6-month and most recent programming intervals.

Speech recognition after implantation of the ossified cochlea.

OBJECTIVE: Insertion of complex, multichannel cochlear implant (CI) electrode arrays into ossified cochleas is now performed routinely. This study describes the hearing results obtained in a consecutive series of 21 patients with obstructed cochleas and compares these results to those in patients with open cochleas. The purpose of this study was to determine whether patients with ossification have speech perception results that are inferior to those of patients with no evidence of cochlear bone formation. STUDY DESIGN: Retrospective analysis of consecutive clinical series. METHODS: CI database review of 191 CI procedures at the University of Miami Ear Institute between 1990 and 1997 showed that 24 (13%) procedures were performed on patients with ossified cochleas. Open-set speech recognition scores obtained on the 11 pediatric and 7 adult English-speaking patients are compared to scores of 51 adult and 61 pediatric English-speaking CI patients with open scala. RESULTS: Results of open-set speech recognition measures in adults and children with ossified cochleas were not significantly different from those of the reference groups. CONCLUSION: Speech recognition results of patients with ossified cochleas are essentially equal to those of patients with open cochleas. Degree of obstruction appears to have less effect on outcome than other factors such as duration of profound deafness or communication methodology in children among this group.

Speech perception results in children with cochlear implants: contributing factors.

Speech perception test results were obtained from a group of 40 pediatric cochlear implant users. Half of the children participated in oral-only habilitation programs, which included both traditional oral and auditory-verbal approaches, and half participated in programs that used a combination of oral and manual communication referred to as total communication (TC). Analysis of the scores showed that children enrolled in oral-only habilitation programs scored significantly higher on the speech perception measures than did children who were enrolled in total communication based programs. These results were inconsistent with those of other reports, which suggested that communication methods had little effect on implant outcomes. To further examine the reasons for the differences in performance, we analyzed 7 additional factors, including length of implant use, age at surgery, device type, socioeconomic status, bilingualism, school setting, and participation in private therapy, which may affect implant performance. Multiple-regression analysis again showed communication mode to be the factor most highly correlated with speech perception abilities among this group of children.

Using the CLARION cochlear implant in cochlear ossification.

This paper is a retrospective review of 5 patients with various degrees of cochlear ossification who were implanted with the CLARION Multi-Strategy Cochlear Implant. Preoperative computed tomography scans, intraoperative findings, surgical technique, and hearing outcomes are discussed in a case report format. Full implantation was achieved in all cases by a systematic approach that included drill-through of proximal obstruction (2 cases), scala vestibuli insertion (2 cases), and complete drill-out (1 case). The only complication was delayed wound healing in a patient with sickle cell disease, chronic active hepatitis, and steroid dependency on antimetabolite therapy. Early results show that the 4 patients with at least 3 months of experience have a mean open-set sentence recognition score of 55% and a mean open-set word recognition score of 24%. The conclusion is that implantation of the Clarion device in ossified cochleas can be successful in all degrees of ossification and can provide significant hearing benefit.

Using electrically evoked auditory reflex thresholds to fit the CLARION cochlear implant.

This paper describes a method for measuring electrically elicited auditory reflex thresholds (EARTs) in young children who use the CLARION Multi-Strategy Cochlear Implant. The EART is an objective measure that can guide the fitting of a cochlear implant in individuals who are unable to perform behavioral tasks required to program the device. Reflexes were obtained in 11 of 17 pediatric Clarion users. The EART current level indicated a point at which an auditory percept was present and the sound was loud, but not uncomfortable. The EART then was used as a basis for conditioning behavioral responses, and as a guideline for setting most comfortable loudness levels.

Cochlear reimplantation.

OBJECTIVE: A small number of multichannel cochlear implant (CI) recipients require reimplantation. This study describes the causes of failure, surgical technique, and hearing outcomes in a consecutive series of 16 patients undergoing reimplantation of multichannel devices. We hypothesize that reimplantation is safe and that hearing results are at least as good as those measured following primary implantation. STUDY DESIGN: Retrospective analysis of consecutive clinical series. METHODS: Chart analysis of 191 consecutive CI operations performed at the University of Miami Ear Institute between 1990 and 1997 revealed 16 patients who received a second multichannel device. All but one had a minimum follow-up of 1 year after reimplantation. Ten of these patients had initial implantation performed by us, and six were initially operated on elsewhere. Main outcomes of the initial procedure were compared with those of the reimplantation, including electrode insertion length, number of channels programmed, and audiometric results. In addition, cause of failure and relevant surgical findings at the second procedure are described. RESULTS: There were no surgical complications after reimplantation surgery. Device failure was the most frequent cause for reimplantation. Time between initial implantation and failure ranged from 0 to 46 months (mean, 22.4 mo; median, 23 mo). Common intraoperative findings include mastoid fibrosis, bone growth at the cochleostomy, and skin flap breakdown. Following reimplantation, mean length of insertion, number of channels actively programmed, and speech recognition scores were at least as good as findings before initial implant failure. CONCLUSION: CI reimplantation is safe and effective.

Hearing results with deep insertion of cochlear implant electrodes.

OBJECTIVE: This study aimed to investigate the relationship of electrode insertion length and speech recognition in patients using Nucleus-22 cochlear implants. STUDY DESIGN: The study design was a retrospective review of a consecutive clinical series. SETTING: The study was conducted at an academic medical center. PATIENTS: Thirty-one postlingually deafened adults with at least 6 months' experience with a Nucleus-22 cochlear implant using Spectra-22 processor and SPEAK strategy participated. MAIN OUTCOME MEASURES: Open-set speech recognition scores for words and sentences were measured. RESULTS: Insertion length ranged from 22 rings (estimated 17 mm) to 32 rings (estimated 25 mm). Mean word recognition score was 35%. Mean sentence score was 69.6%. Statistical analysis showed no correlation between insertion depth and word or sentence scores. CONCLUSION: Insertion of the Nucleus-22 array beyond 22 rings does not improve performance in speech recognition. This finding cannot be generalized to other electrodes or processing strategies.

Surgical technique for implantation of the totally ossified cochlea.

OBJECTIVES: Among the technical challenges of cochlear implant surgery is electrode insertion into the fully ossified cochlea. Earlier drill-out techniques have two significant drawbacks: 1. up to one half fail when the electrode pulls away from the cochlea; and 2. extended radical mastoidectomy, abdominal fat graft for obliteration, and closure of the external auditory meatus are required. A simplified technique is described that allows positive fixation of the cochlear implant electrode and in selected cases avoids a radical cavity with obliteration. STUDY DESIGN: Technical description with case reports and hearing outcomes. METHODS: Ten cadaver temporal bones were dissected to determine middle ear landmarks that overlie the basal turn of the cochlea from the transcanal approach and to establish the feasibility of the intact canal wall procedure. Surgery was performed on four patients who had preoperative imaging evidence of full ossification, two with the canal wall down, and two with canal wall up. Standard measures of speech recognition were used to evaluate hearing. RESULTS: Critical surgical landmarks are the round window, carotid artery, cochleariform process, and oval window. The procedure was successfully performed on four patients and open-set speech recognition is present in each. CONCLUSIONS: This canal wall up procedure allows long electrode insertion without radical cavity/obliteration in patients with fully ossified cochleas and prevents distraction of the electrode from the cochlea. While open-set word recognition was achieved by all subjects, results are poorer than expected for patients with limited or no ossification.

Intact canal wall drill-out procedure for implantation of the totally ossified cochlea.

OBJECTIVE: To describe a simplified drill-out technique for insertion of a multichannel electrode in the completely ossified cochlea without radical mastoidectomy and obliteration. STUDY DESIGN: Description of a new surgical technique and case report. SETTING: Temporal bone dissection laboratory and tertiary referral center. PATIENTS: Adult and pediatric cochlear implant (CI) recipients. MAIN OUTCOME MEASURES: Access for circum-modular drill-out and electrode insertion without radical mastoidectomy and adequate function of multichannel CI. RESULTS: Dissection of 10 cadaver temporal bones demonstrated feasibility of this technique. Highlights include facial recess cochleostomy and 8 mm tunnel; elevation of superiorly based tympanomeatal flap; removal of incus, cochleariform process, and tensor tympani; and identification of carotid canal and use of facial nerve monitor. A case report of an 11-year-year old child with total cochlear ossification and previous failure of a short (8 electrode) CI electrode insertion is presented. Complete insertion of a 22-channel electrode was successful and open-set word recognition is commencing. CONCLUSIONS: The canal wall-up drill-out procedure allows complete electrode insertion without mastoid obliteration in patients with obliterated cochleas. Appropriate attention to the carotid artery and facial nerve is essential.

Surgical techniques for cochlear implantation of the malformed inner ear.

OBJECTIVE: The objective was to describe surgical techniques helpful in implanting children with inner ear malformations. STUDY DESIGN: This was a retrospective chart review and description of surgical techniques in the setting of a tertiary referral center. PATIENTS: The study population was composed of 10 children with inner ear deformities who received 22-channel implants. RESULTS: The primary surgical challenges encountered in these procedures include complete electrode insertion, cerebrospinal fluid gusher, identification of cochleostomy site in the absence of the round window and aberrant facial nerve, and fixation and stabilization of the electrode. CONCLUSIONS: The techniques described allow safe and effective insertion of multichannel electrodes in patients with inner ear malformations.

Single electrode maps in device troubleshooting.

This article presents case studies in which single-channel mapping was used with patients who were experiencing discomfort while using their cochlear implant devices. Repeated psychophysical testing together with integrity testing had failed to locate the source of the problem in each of the described cases. Single-channel mapping was then used as another means of device troubleshooting. Single-channel maps were created for each electrode across the array. In each case, the patient was able to identify the offending electrode(s) during the presentation of speech stimuli, whereas the problem had not been evident during psychophysical testing with pulse stimuli. Eliminating these electrodes from the map alleviated the problems experienced by these implant users in each case.

Electrical middle ear muscle reflex: use in cochlear implant programming.

Programming of multichannel cochlear implants (CIs) requires subjective responses to a series of sophisticated psychophysical percepts. It is often difficult for young prelinguistically deaf children to provide adequate responses for device fitting. This is especially true in setting levels of maximum comfortable loudness, whereby failure to indicate growth of loudness may result in elevation of stimulus levels to the threshold of pain. The acoustic or stapedial muscle reflex has been used previously to provide objective confirmation of acoustic stimulation, and there have been attempts to use the reflex in hearing aid fitting. It has also been suggested that electrically elicited middle ear muscle reflexes (eMEMR) may have applicability in confirming and quantifying electrical stimulation through a CI. To assess the relationship between eMEMR characteristics and levels of loudness perception with CIs, determine reliability of the response, and investigate potential use of eMEMR in CI programming, 25 postlinguistically deafened adult CI users were evaluated. Reflexes have also been attempted on 40 children, with responses present in 31 (71%). Comfort levels predicted by eMEMR were highly correlated with those obtained through subjective judgments in the adult subjects. The eMEMR provides an objective, accurate, and rapid method of estimating maximum comfortable loudness levels, which may be useful in the initial programming of young implant recipients.

Cochlear implants in children with congenital inner ear malformations.

OBJECTIVE: To describe clinical experiences with multichannel cochlear implantation in children with inner ear malformations, including surgical indications and techniques, imaging findings, and outcomes. DESIGN: A retrospective review of a series of 10 consecutive cases with a mean follow-up of 29 months, as well as a review of the literature. SETTING: Academic referral center. SUBJECTS: Ten children who underwent multichannel cochlear implantation for inner ear malformations. High-resolution computed tomographic scans demonstrated a common cavity deformity in 3, an incomplete cochlear partition in 4, and an enlarged vestibule in 1. Two had membranous anomalies as indicated by cerebrospinal fluid gushers at surgery, but the results of imaging were normal. INTERVENTION: All subjects received multichannel cochlear implants. Two subjects underwent mastoid obliteration at the time of implantation owing to preoperative recurrent meningitis or chronic otitis media with episodes of clinical mastoiditis. MAIN OUTCOME MEASURES: The 10 subjects were evaluated for electrode insertion and stability and auditory function for up to 7 years. RESULTS: All 22 electrodes are functional in each child with an incomplete partition, an enlarged vestibule, or a membranous anomaly. Of 3 subjects with common cavities, 2 had full insertion of electrodes and 1 had 16 electrodes inserted. All subjects had speech awareness thresholds detected at 25 dB or better. Three (75%) of the 4 subjects with at least 30 months of experience, including 1 subject with a common cavity, have developed open-set word recognition. CONCLUSIONS: Electrode insertion and hearing results in children with an incomplete partition, an enlarged vestibule, or a membranous anomaly are similar to those in children with normal cochleas. Specific surgical techniques are effective for children with a common cavity, and the results are less certain. Cerebrospinal fluid gushers were encountered frequently but were not difficult to control.

Conservation of residual hearing with cochlear implantation.

HYPOTHESIS: The goals of this work were (a) to review the pre- and postsurgical auditory thresholds in a consecutive sample of cochlear implant recipients to determine the fate of residual hearing, and (b) to obtain preliminary indication of the value of a multicenter longitudinal study of residual hearing in implant patients. BACKGROUND: Indications for cochlear implantation have been expanded to include severely hearing impaired (SHI) adults and may someday include SHI children. Implantation of individuals with more residual hearing is a concern owing to the possible development of better devices that may make use of residual hearing within the lifetime of implanted children if not that of adults. Preservation of residual hearing would be a desirable outcome of implant surgery; however, conventional thought is that implantation destroys any remaining hearing. This study was undertaken to assess if and how often conservation of hearing occurred after implantation in a sample of multichannel implant recipients. METHODS: Records of 50 profoundly hearing impaired consecutively implanted patients were examined for pre- and post-surgical audiometric results. Standard audiometric techniques were used for all testing procedures. Forty patients were considered to have some hearing conserved based on a response obtained at any one of the three speech frequencies prior to implantation. The most recent postimplantation audiometric results were used providing data from users with 1-41 months of use. RESULTS: Twenty-one of 40 implanted subjects were found to have responses in at least one of the speech frequencies both pre- and postsurgery, with the majority of those displaying responses at all three frequencies. In this preliminary retrospective study, it did not appear that duration of cochlear implant use, gender, level of preoperative hearing, or length of electrode insertion were related to outcome. There were insufficient data to draw conclusions on individual devices. CONCLUSIONS: Conservation of hearing occurred in approximately half of the subjects reviewed. There is no indication of what factors contributed to the preservation of hearing in those with postsurgical residual hearing or if that hearing is usable. The study does suggest that a larger multicenter longitudinal study would be of value of determine what factors may be related to conserved hearing in implanted patients.

Otitis media in children with cochlear implants.

Fifty children who received a cochlear implant between 1991 and 1995 were evaluated for incidence of acute otitis media (AOM). Thirty-seven (74%) children had AOM before implantation and 8 (16%) after implantation. All children who had AOM after implantation had a history of AOM. A subgroup of 14 children required ventilating tubes for recurrent AOM before implantation. Five (35.7%) in this group had AOM after implantation. The incidence and severity of AOM decreased after implantation. All episodes of postimplant AOM were successfully treated with routine oral antibiotics, and no infectious complications occurred. A history of recurrent AOM should not inordinately delay cochlear implantation.