Use of Neural Response Telemetry Measures to Objectively Set the Comfort Levels in the Nucleus 24 Cochlear Implant

Cochlear implant programming necessitates accurate setting of programming levels, including maximum stimulation levels, of all active electrodes. Frequently, clinical techniques are adequate for setting these levels; however, they are sometimes insufficient (e.g., very young children). In the Nucleus 24, several methods have been suggested for estimation of comfort levels (C levels) from neural response telemetry (NRT); however, many require co-application of clinical measurements. Data was obtained from 21 adult Nucleus 24 recipients to develop reliable predictions of C levels. Multiple regression analysis was performed on NRT threshold, slope of the NRT growth function, age, length of deafness, length of cochlear implant use and electrode impedance to examine predictive ability. Only the NRT threshold and slope of the growth function measures were significant predictors yielding R2 values from 0.391 to 0.769. Results demonstrated that these measures may provide an alternative means of estimating C levels when other clinical measures are unavailable.

Performance after cochlear implantation in DFNB1 patients

Objective

To evaluate the speech perception and language development with cochlear implants (CI) of DFNB1 children in comparison with non-DFNB1 deaf children.

Study Design

Retrospective case series.

Setting

Academic tertiary center.

Results

Thirty-one congenitally deafened children, screened for GJB2 allele variants, were followed for an average 32 months after CI. With the use of age-appropriate testing, 75% of DFNB1 and 53% of non-DFNB1 children achieved open set word recognition (speech perception category [SPC] level 6). Multivariate analysis showed that SPC was primarily dependent on duration of CI use, but not on the cause of hearing loss. In Reynell language tests, DFNB1 children showed more consistent and quicker gains than non-DFNB1 children.

Conclusion

Although children with CI with DFNB1 show faster gains in Reynell scores, duration of CI use appears to have a greater effect on speech perception than DFNB1 status. SIGNIFICANCE: Identification of DFNB1 children is useful in counseling of CI outcomes.

Changes in Programming over Time in Postmeningitis Cochlear Implant Users

OBJECTIVE: Although successful cochlear implantation of patients with deafness following meningitis is expected, long-term stability of electrical current requirements has not been systematically evaluated. This study evaluated changes in programming for patients deafened by bacterial meningitis and stability of auditory performance over time.

STUDY DESIGN AND SETTING: In this retrospective descriptive study, cochlear implant (CI) stimulation mode and performance of 14 patients deafened by meningitis were compared with those of an age-matched control group of patients deafened by other causes.

RESULTS: There were no significant differences in mean performance between the meningitis group and control group ( P > 0.05). However, the postmeningitis group required progressively higher stimulation levels and higher programming modes over time as compared to the control group.

CONCLUSIONS: Even with deafness accompanied by labyrinthine ossification attributed to meningitis, neural elements were present and could be stimulated. Because increasing levels of stimulation were required over time, postmeningitic children with CIs, and those with cochlear ossification in particular, may need frequent programming adjustments to maintain performance.

SIGNIFICANCE: These patients need close follow-up of stimulation levels and programming modes post-operatively in order to perform optimally with CIs. EBM rating: B-3.

Conservation of Residual Acoustic Hearing After Cochlear Implantation

OBJECTIVE

This study was designed to test the hypothesis that partial hearing conservation is attainable after cochlear implantation with a long perimodiolar electrode. Surgical strategies for hearing conservation during cochlear implantation are described.

STUDY DESIGN

Prospective, single-subject, repeated-measures design.

SETTING

Academic tertiary care center.

PATIENTS

Twenty-eight severely to profoundly hearing-impaired adult cochlear implant recipients who had some measurable hearing preoperatively.

INTERVENTION

Cochlear implantation using Nucleus Freedom Contour Advance electrode.

MAIN OUTCOME MEASURES

Preimplant and postimplant pure-tone thresholds and speech recognition scores were obtained to determine the incidence and degree of conserved hearing at a mean interval of 9 (+/-3.9) months.

RESULTS

Thirty-two percent of subjects experienced complete conservation of hearing (0- to 10-dB loss), and 57% experienced partial conservation of hearing (>11 dB) after implantation. However, open-set speech recognition was partially conserved in only one subject. Cochlear implant performance was not better in patients with conservation of residual hearing.

CONCLUSION

Conservation of pure-tone hearing was possible in 89% of implanted patients; however, residual speech perception was not conserved with this long perimodiolar electrode. A ceiling effect tends to inflate the prevalence of hearing conservation in implantation studies of severely to profoundly hearing-impaired patients.

Revision cochlear implantation for facial nerve stimulation in otosclerosis

OBJECTIVE

To find if patients experiencing postsurgical facial nerve stimulation caused by underlying disease process (ie, otosclerosis) can improve their hearing performance with their cochlear implant by reimplantation and by an optimal programming strategy.

DESIGN

Retrospective analysis.

SETTING

Academic tertiary referral center.

PATIENTS

Two cochlear otosclerosis patients with resistant facial nerve stimulation (FNS). Both patients were initially implanted with Nucleus 22 devices (Cochlear Corporation, Englewood, Colo) and they developed FNS after a period of use. Owing to the decreasing number of active electrodes, concurrent decreases in speech understanding occurred.

INTERVENTIONS

Various programming approaches were used to address the FNS. Both subjects ultimately received Nucleus 24 devices. One was reimplanted in the same ear, and the other was implanted in the opposite ear. Both have been followed up for 8 months following the reimplantation.

MAIN OUTCOME MEASURES

Cochlear implant programming levels, cochlear implant performance, and facial nerve stimulation.

RESULTS

The FNS was managed for more than 3 years through optimized programming. However, the FNS progressed until performance dropped below acceptable levels. Reimplantation was believed to be the only option for improvement. After reimplantation and programming, both subjects showed immediate improvement in speech discrimination. One user increased his consonant-nucleus-consonant word score from 12% preoperatively to 42%, and the other's performance increased from 0% to 86%.

CONCLUSIONS

Our results suggest that having more programming options with newer devices is critical in otosclerotic or ossified users who experience FNS. Also, reimplantation may be a useful tool to improve performance.

Facial nerve stimulation after cochlear implantation

OBJECTIVES

This study was designed to compare the incidence and nature of facial nerve stimulation (FNS) in patients receiving cochlear implants (CI) manufactured by Cochlear Corporation, Advanced Bionics Corporation, and MedEl.

STUDY DESIGN

Retrospective chart review at a tertiary referral center.

METHODS

The charts of 600 patients who received CIs from 1993 to 2003 with at least 1 year of follow-up were reviewed for significant FNS (FNS on at least 1 channel at functional stimulation levels). Data collected included age, sex, etiology of deafness, device type, electrode, FNS onset after initial stimulation, number and location of electrode contacts causing FNS, and loudness level at which FSN occurred. Nucleus straight and perimodiolar electrodes were also compared.

RESULTS

Thirty-nine of 600 (6.5%) patients had FNS on at least one channel, (MedEl 3 of 43 [7.0%], Nucleus 29 of 440 [6.6%], and Clarion 7 of 117 [6.0%]). The incidence of FNS in Nucleus perimodiolar electrodes (16 of 250 [6.4%]) was similar to straight electrodes (13 of 190 (6.8%]), as was the mean number of electrodes causing FNS per patient (11 vs. 12). However, straight electrodes caused stimulation at significantly softer perceived loudness levels than perimodiolar electrodes (P < .0001).

CONCLUSIONS

In this large series of CI FNS, the overall incidence of FNS is consistent with previous reports. All devices had a similar incidence of FNS, but perimodiolar electrodes produced FNS only at significantly higher loudness levels than straight electrodes, making them preferable for patients at risk for FNS receiving Nucleus devices.

Further prospective findings with compound action potentials from Nucleus 24 cochlear implants

The purpose of this study was to gain greater understanding of compound action potential (CAP) specific characteristics including: slope of the growth function, P1-N1 amplitude, threshold and latencies of P1 and N1 measured in cochlear implant users. Experienced adult subjects underwent behavioral threshold (T) measurement and electrically elicited stapedial reflex (eSR) recording, followed by CAP measurements on six selected electrodes. Based on the electrically elicited stapedial reflex threshold (eSRT), maximum stimulation level for each measured electrode was set. Relationships among the three thresholds of the above measures and maximum CAP P1-N1 amplitude and slope of the growth function were statistically evaluated for each measured electrode. Threshold of the CAP response showed relationships of similar strength with eSRT and T (r=0.69 and 0.61, respectively). For both slope of the growth function and CAP P1-N1 amplitude, a statistically significant relationship with cochlear place was found. Both specific characteristics of CAP measurement for the most apical electrodes were roughly double those for the most basal electrode (alpha=0.05). This may be partially explained by cochlear anatomy and is consistent with prior mammalian and human studies showing increasing density and survival of spiral ganglion cells in the regions corresponding to intracochlear electrode placement from basal to apical electrodes (90-360 degrees ).

Cochlear implants in children--a review

Over the past two decades, cochlear implantation has become a widely accepted treatment of deafness in children. Over 20,000 children have received cochlear implants worldwide. Hearing, language and social development outcomes have been positive. We review current issues in cochlear implantation, candidacy, evaluation, surgery, habilitation, ethics and outcomes.

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 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.

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.

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.

Ethics of Cochlear Implantation in Young Children

Certain leaders of the Deaf community are attempting to generate opposition to cochlear implants in children by pitting the rights of deaf children and their families against the needs of deaf society. They have labeled physicians as unethical and CIs as “child abuse,” resulting in misunderstanding, anger, and violence. However, the arguments of these leaders are internally contradictory: they hold that deafness is not a disability but support disability benefits for the deaf; they maintain both that cochlear implants do not work and that they work so well that they are “genocidal” (i.e., they will eliminate deafness). Their positions oppose the ethical principles of beneficence and autonomy as they relate to self-determination and privacy. Ethical standards hold that the best interests of the child precede those of a special interest group and that parents have the responsibility to determine their children's best interests.

Update on cochlear implantation

Cochlear implants are computerized devices that partially replace the transduction and encoding functions of the cochlea. Over the past 20 years studies have demonstrated that cochlear implants are safe and effective, with modern computer-based multichannel devices providing open-set word understanding for the majority of implanted postlingually deafened adults as well as pre- and postlingually deafened children. Advances in word processing strategy have led to ever-improving word recognition skills and recent studies have demonstrated that oral language develops in congenitally deaf children who use cochlear implants.

Misleading the deaf community about cochlear implantation in children

Activists are misleading the deaf community in an effort to generate opposition to cochlear implants in children. Their methods include both misinformation and the use of inflammatory, illogical rhetoric. To date they have been successful in causing anger, frustration, and overt violence among the culturally deaf with the use of such terms as "genocide" and "child abuse." Because the average reading level of a deaf residential high school graduate is at the third or fourth grade level, a small elite is able to control the interpretation and flow of complex information to many deaf people. It is a challenge to make accurate information, both positive and negative, accessible directly to deaf society. Just as the deaf have abandoned opposition to cochlear implants in adults, the same might be expected to occur in children when they and their parents become aware of the results of implantation.

Electric auditory brain-stem responses in nucleus multichannel cochlear implant users

OBJECTIVE

The electrically elicited auditory brain-stem response (EABR) has been proposed as a tool for use in cochlear implant device setting. To systematically examine the relationships of psychophysical perceptions and EABRs, implant users underwent a series of comparative measurements. The characteristics of the EABR were assessed for their predictive value in determining the subjective measures needed to set the implant device.

DESIGN

Characteristics of the EABR and various perceptual measures in a group of cochlear implant users served as compared variables in a correlational study.

SETTING

The study was carried out in the audiology clinic of a university hospital. The audiology clinic maintained a fully equipped evoked potential laboratory, and was part of an otolaryngology department that supported a cochlear implant program.

SUBJECTS

The subjects consisted of 10 consecutively selected postlinguistically deafened adult multichannel cochlear implant users.

MAIN OUTCOME MEASURES

Morphology, latency, and amplitude measures of the EABR recordings were compared with behavioral perceptions of threshold, most comfortable and uncomfortable loudness levels.

RESULTS

Perceptual measures of threshold were found to be significantly related to the threshold of the EABR across subjects and electrode position. Simple linear regression analysis was used to measure the degree of the relationship. An r value of 0.89 attests to a significant relationship. The EABR wave latencies and amplitudes were found to have no significant relationship to any of the perceptual measures examined.

CONCLUSIONS

Although EABR cannot replace behavioral measurements for device setting, in difficult cases EABR thresholds may be used as a starting point from which to estimate settings for the device.

Cochlear endoscopy with preservation of hearing in guinea pigs

Advances in fiberoptic technology have revolutionized the way many disorders are treated by otolaryngologists. We have previously described our experiences with cochlear endoscopy during cochlear implantation. However, endoscopy of the functioning cochlea has not previously been reported. To test the hypothesis that endoscopy of the guinea pig cochlea is possible without catastrophic loss of auditory function, we subjected 20 ears of 10 Hartley-strain albino guinea pigs to limited endoscopy of the cochlea through the round window with evaluation of distortion product otoacoustic emissions and auditory brain stem responses. Insertion of the endoscope caused measurable changes in auditory brain stem response latency and amplitude. Distortion product otoacoustic emission amplitudes were reduced an average of 6 dB with greater loss close to the round window. Frequencies above 18 kHz, corresponding to the region of endoscopy, were not evaluated in this preliminary study and are suspected to have sustained more damage. Results demonstrate that endoscopy of the guinea pig cochlea is possible without major loss of the above physiologic measures in the regions tested. If endoscopy of the cochlea is to become a tool with clinical and basic science applications, refinements in techniques to avoid damage are necessary.

Ophthalmologic abnormalities in the pediatric cochlear implant population

To determine the nature and prevalence of ophthalmologic abnormalities in children with congenital or prelinguistic sensorineural deafness, we performed complete ophthalmologic examinations on 54 children aged 2 to 14 years from the University of Miami Ear Institute's Cochlear Implant Program. Of 54 children, 33 (61.1%) had some form of ophthalmologic abnormality, with the majority (24 patients; 44.4%) being refractive errors. Of 54 patients, two (3.7%) had strabismus and two (3.7%) had external adnexal anomalies. One child (1.8%) had cataracts. The cause of the deafness, which had previously been unknown, was determined in three of 54 cases (5.6%) as a result of ocular examinations documenting rubella retinopathy, tapetoretinal degeneration (Usher's syndrome), and iris heterochromia (Waardenburg's syndrome). Routine ophthalmologic examination must be mandated for this population, and the ophthalmologist should be encouraged to play a broader role in the care of children with deficiencies of both vision and audition.

Visual function in children with congenital sensorineural deafness

Images

Multichannel cochlear implant and electrically evoked auditory brainstem responses in a child with labyrinthitis ossificans

Ossification of the cochlea following meningitis presents a surgical challenge. Electrode mapping, especially in the young child, is difficult given the uncertainty of electrode contact with viable neural elements. This paper reviews surgical technique and the use of auditory brainstem responses to map the electrodes. A 4-year-old child deafened by meningitis at age 20 months had bilateral cochlear ossification by computed tomography. At surgery, a canal wall-down mastoidectomy and closure of the ear canal were performed. A trough around the modiolus was drilled, and the electrode array was placed in it. Post-operatively, the patient gave aversive or no responses to electrode stimulation. To assess electrode function, auditory brainstem responses to individual electrode activation were obtained under general anesthesia. Functioning electrodes could thus be selected for mapping. The patient now responds well to sound.

Meningitis and facial paresis. Implications for cochlear implantation

Most postlingually deafened individuals receive auditory sensations with a cochlear implant. We describe a postmeningitic patient with bilateral facial paresis who failed to be stimulated with a multichannel device. In light of the facial dysfunction, primary auditory nerve damage by meningitis is postulated as the cause of implant failure. Preoperation electrical stimulation of the cochlea using an alternating current signal is recommended as a means of assessing cochlear implant candidacy.