A sensitive period for the development of the central auditory system in children with cochlear implants: implications for age of implantation

OBJECTIVE

The aim of the present experiment was to assess the consequences of cochlear implantation at different ages on the development of the human central auditory system.

DESIGN

Our measure of the maturity of central auditory pathways was the latency of the P1 cortical auditory evoked potential. Because P1 latencies vary as a function of chronological age, they can be used to infer the maturational status of auditory pathways in congenitally deafened children who regain hearing after being fit with a cochlear implant. We examined the development of P1 response latencies in 104 congenitally deaf children who had been fit with cochlear implants at ages ranging from 1.3 yr to 17.5 yr and three congenitally deaf adults. The independent variable was the duration of deafness before cochlear implantation. The dependent variable was the latency of the P1 cortical auditory evoked potential.

RESULTS

A comparison of P1 latencies in implanted children with those of age-matched normal-hearing peers revealed that implanted children with the longest period of auditory deprivation before implantation-7 or more yr-had abnormal cortical response latencies to speech. Implanted children with the shortest period of auditory deprivation-approximately 3.5 yr or less-evidenced age-appropriate latency responses within 6 mo after the onset of electrical stimulation.

CONCLUSIONS

Our data suggest that in the absence of normal stimulation there is a sensitive period of about 3.5 yr during which the human central auditory system remains maximally plastic. Plasticity remains in some, but not all children until approximately age 7. After age 7, plasticity is greatly reduced. These data may be relevant to the issue of when best to place a cochlear implant in a congenitally deaf child.

Pre-, per- and postoperative factors affecting performance of postlinguistically deaf adults using cochlear implants: a new conceptual model over time

OBJECTIVE

To test the influence of multiple factors on cochlear implant (CI) speech performance in quiet and in noise for postlinguistically deaf adults, and to design a model of predicted auditory performance with a CI as a function of the significant factors.

STUDY DESIGN

Retrospective multi-centre study.

METHODS

Data from 2251 patients implanted since 2003 in 15 international centres were collected. Speech scores in quiet and in noise were converted into percentile ranks to remove differences between centres. The influence of 15 pre-, per- and postoperative factors, such as the duration of moderate hearing loss (mHL), the surgical approach (cochleostomy or round window approach), the angle of insertion, the percentage of active electrodes, and the brand of device were tested. The usual factors, duration of profound HL (pHL), age, etiology, duration of CI experience, that are already known to have an influence, were included in the statistical analyses.

RESULTS

The significant factors were: the pure tone average threshold of the better ear, the brand of device, the percentage of active electrodes, the use of hearing aids (HAs) during the period of pHL, and the duration of mHL.

CONCLUSIONS

A new model was designed showing a decrease of performance that started during the period of mHL, and became faster during the period of pHL. The use of bilateral HAs slowed down the related central reorganization that is the likely cause of the decreased performance.

Language skills of children with early cochlear implantation

OBJECTIVE

This study investigated factors contributing to the comprehension and production of English language by children with prelingual deafness after 4 to 7 yr of multichannel cochlear implant use. The analysis controlled for the effects of child and family characteristics so that educational factors most conducive to maximum implant benefit could be identified.

DESIGN

A battery of language tests were administered to 181 8- and 9 yr-old children from across the United States and Canada who received a cochlear implant by age 5. Tests of comprehension, verbal reasoning, narrative ability and spontaneous language production were administered either in speech and sign or in the child's preferred communication mode. These constituted the Total Language measures. Spoken Language measures were derived from a speech-only language sample. Type and amount of educational intervention since implantation constituted the independent variables. Characteristics of the child and the family were considered intervening variables. A series of multiple regression analyses determined the amount of variance in Total Language and Spoken Language ability accounted for by the intervening variables and the amount of additional variance attributable to the independent variables.

RESULTS

More than half of the children (with performance intelligence quotients in the average range) exhibited language skills that were similar to those of hearing 8 to 9 yr olds on measures of verbal reasoning, narrative ability, utterance length, and lexical diversity. Significant predictors of language ability were similar for Total and for Spoken Language outcomes and included greater nonverbal intelligence, smaller family size, higher socio-economic status and female gender. Age at receiving an implant did not affect language outcome. After the variance due to these variables was controlled, the primary rehabilitative factors associated with linguistic outcome were amount of mainstream class placement and an educational emphasis on speech and auditory skills.

CONCLUSIONS

Use of a cochlear implant has had a dramatic impact on the linguistic competence of profoundly hearing-impaired children. More than half of the children in this sample with average learning ability produced and understood English language at a level comparable with that of their hearing age mates. Such mature language outcomes were not typical of children with profound hearing loss who used hearing aids. Use of a visual (i.e., sign) language system did not provide the linguistic advantage that had been anticipated. Children educated without use of sign exhibited a significant advantage in their use of narratives, the breadth of their vocabulary, in their use of bound morphemes, in the length of their utterances and in the complexity of the syntax used in their spontaneous language. An oral educational focus provided a significant advantage for both spoken and total language skills.

Incapacitating Unilateral Tinnitus in Single-Sided Deafness Treated by Cochlear Implantation

Objectives:

Tinnitus is a well-known, difficult-to-treat symptom of hearing loss. Users of cochlear implants (CIs) have reported a reduction in tinnitus following implantation for bilateral severe-to-profound deafness. This study assessed the effect of electrical stimulation via a CI on tinnitus in subjects with unilateral deafness and ipsilateral tinnitus who underwent implantation in an attempt to treat tinnitus with the CI.

Methods:

Twenty-one subjects who complained of severe intractable tinnitus that was unresponsive to treatment received a CI. Tinnitus loudness was measured with a Visual Analog Scale; loudness percepts were recorded with the device activated and deactivated. Tinnitus distress was measured with the Tinnitus Questionnaire before and after implantation.

Results:

Electrical stimulation via a CI resulted in a significant reduction in tinnitus loudness (mean ± SD; 1 year after implantation, 2.4 ± 1.8; 2 years after implantation, 2.5 ± 1.9; before implantation, 8.5 ± 1.3). With the device deactivated, tinnitus loudness was still reduced to between 6.1 and 7.0 over 24 months. The Tinnitus Questionnaire revealed a significant positive effect of CI stimulation.

Conclusions:

Unilateral tinnitus resulting from single-sided deafness can be treated with electrical stimulation via a CI. The outcomes of this pilot study demonstrate a new method for treatment of tinnitus in select subjects, perhaps an important new indication for cochlear implantation.

Speech recognition as a function of the number of electrodes used in the SPEAK cochlear implant speech processor

Speech recognition was measured in listeners with the Nucleus-22 SPEAK speech processing strategy as a function of the number of electrodes. Speech stimuli were analyzed into 20 frequency bands and processed according to the usual SPEAK processing strategy. In the normal clinical processor each electrode is assigned to represent the output of one filter. To create reduced-electrode processors the output of several adjacent filters were directed to a single electrode, resulting in processors with 1, 2, 4, 7, 10, and 20 electrodes. The overall spectral bandwidth was preserved, but the number of active electrodes was progressively reduced. After a 2-day period of adjustment to each processor, speech recognition performance was measured on medial consonants, vowels, monosyllabic words, and sentences. Performance with a single electrode processor was poor in all listeners, and average performance increased dramatically on all test materials as the number of electrodes was increased from 1 to 4. No differences in average performance were observed on any test in the 7-, 10-, and 20-electrode conditions. On sentence and consonant tests there was no difference between average performance with the 4-electrode and 20-electrode processors. This pattern of results suggests that cochlear implant listeners are not able to make full use of the spectral information on all 20 electrodes. Further research is necessary to understand the reasons for this limitation and to understand how to increase the amount of spectral information in speech received by implanted listeners.

Relationships among speech perception, production, language, hearing loss, and age in children with impaired hearing

Eighty-seven primary-school children with impaired hearing were evaluated using speech perception, production, and language measures over a 3-year period. Forty-seven children with a mean unaided pure-tone-average hearing loss of 106 dB HL used a 22-electrode cochlear implant, and 40 with a mean unaided pure-tone-average hearing loss of 78 dB HL were fitted with hearing aids. All children were enrolled in oral/aural habilitation programs, and most attended integrated classes with normally hearing children for part of the time at school. Multiple linear regression was used to describe the relationships among the speech perception, production, and language measures, and the trends over time. Little difference in the level of performance and trends was found for the two groups of children, so the perceptual effect of the implant is equivalent, on average, to an improvement of about 28 dB in hearing thresholds. Scores on the Peabody Picture Vocabulary Test (PPVT) and the Clinical Evaluation of Language Fundamentals showed an upward trend at about 60% of the rate for normally hearing children. Rates of improvement for individual children were not correlated significantly with degree of hearing loss. The children showed a wide scatter about the average speech production score of 40% of words correctly produced in spontaneous conversations, with no significant upward trend with age. Scores on the open-set Consonant-Nucleus-Consonant (CNC) monosyllabic word test and the Bench-Kowal-Bamford (BKB) sentence test were strongly related to language level (as measured by an equivalent age on the PPVT) and speech production scores for both auditory-visual and auditory test conditions. After allowing for differences in language, speech perception scores in the auditory test condition showed a slight downward trend over time, which is consistent with the known biological effects of hearing loss on the auditory periphery and brainstem. Speech perception scores in the auditory condition also decreased significantly by about 5% for every 10 dB of hearing loss in the hearing aid group. The regression analysis model allows separation of the effects of language, speech production, and hearing levels on speech perception scores so that the effects of habilitation and training in these areas can be observed and/or predicted. The model suggests that most of the children in the study will reach a level of over 90% sentence recognition in the auditory-visual condition when their language becomes equivalent to that of a normally hearing 7-year-old, but they will enter secondary school at age 12 with an average language delay of about 4 or 5 years unless they receive concentrated and effective language training.

Factors associated with development of speech perception skills in children implanted by age five

OBJECTIVE

This study investigated factors contributing to speech perception outcomes in children with prelingual deafness after 4 to 7 yr of multichannel cochlear implant use. The analysis controlled for the effects of child, family and implant characteristics so that educational factors most conducive to maximum implant benefit could be identified.

DESIGN

One hundred eighty-one 8- and 9-yr-old children from across the US and Canada who received a cochlear implant by age 5 were administered a battery of speech perception tests. Type and amount of educational intervention since implantation constituted the independent variables. Characteristics of the child, the family, and the implant itself constituted intervening variables. A series of multiple regression analyses determined the amount of variance in speech perception ability accounted for by the intervening variables and the amount of additional variance attributable to independent variables.

RESULTS

The children achieved an average level of about 50% open-set speech perception through listening alone and almost 80% through lipreading and listening together, but with scores for individual children ranging from 0 to 100% correct. Over half of the variance in speech perception scores was predicted by characteristics of the child, family, implant and educational program. Significant predictors of good speech perception included greater nonverbal intelligence, smaller family size, longer use of the updated SPEAK/CIS processing strategy, a fully active electrode array, greater electrical dynamic range between threshold and maximum comfort level, and greater growth of loudness with increasing stimulus intensity. After the variance due to these variables was controlled, the primary rehabilitative factor associated with good speech perception skill development was educational emphasis on oral-aural communication.

CONCLUSIONS

Children with profound hearing loss achieved unprecedented levels of speech perception skill 4 to 7 yr after cochlear implantation. Use of an updated speech processor, such as SPEAK, contributed significantly to improved speech perception skills, even in children who were initially fitted with an earlier strategy, such as M-PEAK. In addition, the audiologist who programs the cochlear implant makes an important contribution to the child's successful outcome with the device. A well-fitted map, as evidenced by a wide dynamic range and optimal growth of loudness characteristics, contributed substantially to the child's ability to hear speech. Finally, the classroom communication mode used in the child's school affects speech perception outcome. Children whose educational program emphasized dependence on speech and audition for communication were better able to use the information provided by the implant to understand speech.

Mental health of deaf people

Deafness is a heterogeneous condition with far-reaching effects on social, emotional, and cognitive development. Onset before language has been established happens in about seven per 10,000 people. Increased rates of mental health problems are reported in deaf people. Many regard themselves as members of a cultural minority who use sign language. In this Review, we describe discrepancies between a high burden of common mental health disorders and barriers to health care. About a quarter of deaf individuals have additional disabilities and a high probability of complex mental health needs. Research into factors affecting mental health of deaf children shows that early access to effective communication with family members and peers is desirable. Improved access to health and mental health care can be achieved by provision of specialist services with professionals trained to directly communicate with deaf people and with sign-language interpreters.

Measures of working memory span and verbal rehearsal speed in deaf children after cochlear implantation

Large individual differences in spoken word recognition performance have been found in deaf children after cochlear implantation. Recently, Pisoni and Geers (2000) reported that simple forward digit span measures of verbal working memory were significantly correlated with spoken word recognition scores even after potentially confounding variables were statistically controlled for. The present study replicates and extends these initial findings to the full set of 176 participants in the CID cochlear implant study. The pooled data indicate that despite statistical "partialling-out" of differences in chronological age, communication mode, duration of deafness, duration of device use, age at onset of deafness, number of active electrodes, and speech feature discrimination, significant correlations still remain between digit span and several measures of spoken word recognition. Strong correlations were also observed between speaking rate and both forward and backward digit span, a result that is similar to previously reported findings in normal-hearing adults and children. The results suggest that perhaps as much as 20% of the currently unexplained variance in spoken word recognition scores may be independently accounted for by individual differences in cognitive factors related to the speed and efficiency with which phonological and lexical representations of spoken words are maintained in and retrieved from working memory. A smaller percentage, perhaps about 7% of the currently unexplained variance in spoken word recognition scores, may be accounted for in terms of working memory capacity. We discuss how these relationships may arise and their contribution to subsequent speech and language development in prelingually deaf children who use cochlear implants.

The relationship between EAP and EABR thresholds and levels used to program the nucleus 24 speech processor: data from adults

OBJECTIVE

The objective of this study was to determine the relationship between electrically evoked whole nerve action potential (EAP) and electrical auditory brain stem response (EABR) thresholds and MAP threshold (T-level) and maximum comfort level (C-level) for subjects who use the Nucleus 24 cochlear implant system.

DESIGN

Forty-four adult Nucleus 24 cochlear implant users participated in this study. EAP thresholds were recorded using the Neural Response Telemetry System developed by Cochlear Corporation. EABR thresholds were measured for a subset of 14 subjects using standard evoked potential techniques. These physiologic thresholds were collected on a set of five electrodes spaced across the cochlea, and were then compared with behavioral measures of T-level and C-level used to program the speech processor.

RESULTS

EAP thresholds were correlated with MAP T- and C-levels; however, the correlation was not strong. A technique for improving the correlation by combining measures of T- and C-levels made on one electrode with the EAP thresholds was presented. Correlations between predicted and measured T- and C-levels using this technique were 0.83 and 0.77, respectively. Similar results were obtained using the EABR thresholds for a smaller set of subjects. In general, EABR thresholds were recorded at levels that were approximately 4.7 programming units lower than EAP thresholds.

CONCLUSIONS

Either EAP or EABR thresholds can be used in combination with a limited amount of behavioral information to predict MAP T- and C-levels with reasonable accuracy.

Preservation of residual hearing with cochlear implantation: how and why

CONCLUSIONS

Hearing may be conserved in adults after implantation with the Nucleus Contour Advance perimodiolar electrode array. The degree of hearing preservation and the maximum insertion depth of the electrode array can vary considerably despite a defined surgical protocol. Residual hearing combined with electrical stimulation in the same ear can provide additional benefits even for conventional candidates for cochlear implantation.

OBJECTIVES

We present preliminary results from a prospective multicentre study investigating the conservation of residual hearing after implantation with a standard-length Nucleus Contour Advance perimodiolar electrode array and the benefits of combined electrical and acoustic stimulation.

MATERIAL AND METHODS

The subjects were 12 adult candidates for cochlear implantation recruited according to national selection criteria. A "soft" surgery protocol was defined, as follows: 1-1.2-mm cochleostomy hole anterior and inferior to the round window; Nucleus Contour Advance electrode array inserted using the "Advance-off-stylet" technique; and insertion depth controlled by means of three square marker ribs left outside the cochleostomy hole. These procedures had been shown to reduce insertion forces in temporal bone preparations. Variations in surgical techniques were monitored using a questionnaire. Pure-tone thresholds were measured pre- and postoperatively. Patients who still retained thresholds <90 dB HL for frequencies up to 500 Hz were re-fitted with an in-the-ear (ITE) hearing aid. Word recognition was tested in quiet and sentence perception in noise for the cochlear implant alone and in combination with an ipsilateral hearing aid.

RESULTS

Hearing threshold level data were available for 12 patients recruited from 6 of the centres. Median increases in hearing threshold levels were 23, 27 and 33 dB for the frequencies 125, 250 and 500 Hz, respectively. These median increases include the data for two patients who had total loss of residual hearing due to difficulties encountered during surgery. "Cochlear view" X-ray images indicated that the depth of insertion varied between 300 and 430 degrees, despite modest variations in the length of the electrode inserted (17-19 mm). The insertion angle had some influence on the preservation of residual hearing at frequencies of 250-500 Hz. Six of the 12 patients retained sufficient hearing for effective use of an ipsilateral ITE hearing aid (< or = 80 dB HL at 125 and 250 Hz; < or = 90 dB HL at 500 Hz). Word recognition scores in quiet were improved from 10% to 30% with the cochlear implant plus ipsilateral hearing aid in 3 patients who had at least 3 months postoperative experience. Signal:noise ratio thresholds for sentence recognition were improved by up to 3 dB. Patients reported that they experienced greatly improved sound quality and preferred to use the two devices together.

Hearing preservation in cochlear implantation for electric acoustic stimulation

OBJECTIVE

To evaluate the possibility of preservation of low-frequency hearing in atraumatic cochlear implant electrode insertion procedures for combined, ipsilateral electric and acoustic stimulation.

MATERIAL AND METHODS

A total of 21 patients were implanted with a MED EL C40+ cochlear implant using an atraumatic electrode insertion technique to preserve residual low-frequency hearing. Pure-tone audiometric thresholds were measured pre- and postoperatively to evaluate the degree of preserved hearing. Speech discrimination tests in quiet and with background noise were performed in a patient with successful hearing preservation.

RESULTS

Using the atraumatic electrode insertion procedure with an insertion depth of 360 degrees (18-24 mm), hearing preservation could be achieved in 18/21 patients (85.7%). Three patients (14.3%) lost their residual low-frequency hearing after the implantation. Residual hearing was preserved completely in 13 patients (61.9%) and partial hearing preservation was possible in 5 (23.8%). Preliminary speech discrimination tests showed a dramatic benefit for the combined electric and acoustic stimulation mode compared to cochlear implantation alone.

CONCLUSION

Preservation of low-frequency hearing in cochlear implantation is possible in patients implanted because of profound high-frequency deafness. With the development of new, more atraumatic electrode designs, preservation of residual hearing should be further improved.

The benefits of combining acoustic and electric stimulation for the recognition of speech, voice and melodies

Fifteen patients fit with a cochlear implant in one ear and a hearing aid in the other ear were presented with tests of speech and melody recognition and voice discrimination under conditions of electric (E) stimulation, acoustic (A) stimulation and combined electric and acoustic stimulation (EAS). When acoustic information was added to electrically stimulated information performance increased by 17-23 percentage points on tests of word and sentence recognition in quiet and sentence recognition in noise. On average, the EAS patients achieved higher scores on CNC words than patients fit with a unilateral cochlear implant. While the best EAS patients did not outperform the best patients fit with a unilateral cochlear implant, proportionally more EAS patients achieved very high scores on tests of speech recognition than unilateral cochlear implant patients.

Age at implantation: its importance in pediatric cochlear implantation

OBJECTIVE

To assess the influence of age at implantation on speech perception and speech intelligibility following pediatric cochlear implantation.

STUDY DESIGN

A prospective study was undertaken on a consecutive group of 126 congenital and prelingually deaf children up to 4 years after implantation. The study group was confined to prelingually deaf children less than 7 years of age at the time of implantation. All had implantation with the same multichannel cochlear implant system. No child was lost to follow-up, and there were no exclusions from the study.

METHODS

The Iowa Matrix Closed Set Sentence test, connected discourse tracking, categories of auditory performance, and speech intelligibility rating were used to assess the speech perception (closed and open set) and speech intelligibility of the children with implants. Regression analysis and Spearman rank correlation coefficients were used to assess the correlation between the outcome measures with age at implantation. The setting was a tertiary referral pediatric cochlear implant center in the United Kingdom.

RESULTS

Age at implantation positively correlated with preimplantation assessment performance and with most of the outcome measures up to 24 months following implantation. However, at the 3-and 4-year intervals following implantation, age at implantation was found to be a strong negative predictor of all the outcomes studied (correlation coefficients ranging from -0.44 to -0.58, all statistically significant [P<.05]).

CONCLUSIONS

The results of the present study provide strong evidence that prelingually deaf children should receive implants as early as possible to facilitate the later development of speech perception skills and speech intelligibility and thus maximize the health gain from the intervention. However, because of the wide variation in individual outcomes, age alone should not be used as a criterion to decide implant candidacy.

Effect of Age at Cochlear Implantation on Auditory Skill Development in Infants and Toddlers

OBJECTIVES

To investigate the effect of age at cochlear implantation on the auditory development of children younger than 3 years and to compare these children's auditory development with that of peers with normal hearing.

DESIGN

Using a repeated-measures paradigm, auditory skill development was evaluated before and 3, 6, and 12 months after implantation. Data were compared with previously published data from cohorts with normal hearing.

PARTICIPANTS

One hundred seven hearing-impaired children (age range, 12-36 months) who received a cochlear implant during clinical trials in North America.

MAIN OUTCOME MEASURE

Auditory skill development was assessed using the Infant-Toddler Meaningful Auditory Integration Scale, a tool that provides a quantitative measure in children as young as newborns.

RESULTS

Infants and toddlers who receive implants show rapid improvement in auditory skills during the first year of device use regardless of age at implantation, although younger children achieve higher scores. Children who undergo implantation at a younger age acquire auditory skills nearer to those of their peers with normal hearing at a younger age. The mean rate of acquisition of auditory skills is similar to that of infants and toddlers with normal hearing regardless of age at implantation.

CONCLUSION

Performing implantation in children with profound hearing loss at the youngest age possible allows the best opportunity for them to acquire communication skills that approximate those of their peers with normal hearing.

Cochlear implantation outcomes in adults: A scoping review

OBJECTIVES

This study aimed to provide a descriptive analysis of recent evidence available in the literature in relation to the efficacy of unilateral cochlear implantation in adults, the general findings of these studies, and the populations to which these findings apply. It also aimed to appraise the individual success rate and the magnitude of benefit following implantation.

DESIGN

A scoping review was conducted to identify English-language, peer-reviewed journal articles published between 2000 and 2018 assessing the outcomes of cochlear implantation in adults who received their first cochlear implant from 2000 onwards. To be included, studies had to report speech perception or self-reported measures of listening or quality of life at least three months after implantation. Systematic searches were conducted in Medline, Embase, Web of Science and Google Scholar. A two-stage screening approach was used, with seven reviewers independently screening titles and abstracts against inclusion criteria and three from this group further reviewing full-texts. A data charting form was developed and trialled, with 10% of the study data extracted in duplicate to compare results and further refine the form. Data relevant for efficacy analyses were extracted from studies with sample sizes of at least 10 participants.

RESULTS

A total of 4182 abstracts were screened against inclusion criteria, and of these, 603 full-texts were further screened. After exclusion of non-eligible articles, 201 articles were included in the first part of this scoping review. The majority of these articles were case series or comparative studies without a concurrent group, and had small sample sizes. Data synthesis conducted with the 102 articles with more than 10 participants highlighted that the average word perception ability improved from 8.2% to 53.9% after implantation. Self-reported benefit improved by 21.5 percentage points. At the individual level, 82.0% of adults with postlingual hearing loss and 53.4% of adults with prelingual hearing loss improved their speech perception ability by 15 percentage points or more. A small proportion had poorer ability after implantation or had stopped using the cochlear implant.

CONCLUSIONS

Despite broad inconsistencies in measurement, research design, and reporting across articles, it is evident that cochlear implantation is beneficial to the majority of adults of any age who have limited aided speech perception abilities. While many adults with severe-to-profound hearing loss may also have poor speech perception abilities with hearing aids, the validity of using hearing loss severity as a criterion for cochlear implantation has not been demonstrated. Clinical and research recommendations derived from this review are provided.

Factors associated with development of speech production skills in children implanted by age five

OBJECTIVE

This study investigated speech production outcomes and the factors influencing the outcomes in children who had 4 to 6 yr of experience with a multichannel cochlear implant. Production variables examined included speech intelligibility, accuracy of consonant and vowel production, percentage of plosives and fricatives produced, duration of sentences, percentage of time involved in communication breakdowns during a communication sample, and responses to a speech usage questionnaire.

DESIGN

181 children between the ages of 8 and 9 yr who received a multichannel cochlear implant before age 5 yr participated as subjects. Independent variables were the amount and type of educational intervention and intervening variables were distributed across child, family and implant characteristics. Multiple regression analyses provided a measure of the amount of variance associated with speech production skills accounted for by the intervening and independent variables.

RESULTS

Performance for the key words in the speech intelligibility measured averaged 63.5% for the group of children. Accuracy of phoneme production was higher for consonants (68.0%) than for vowels (61.6%) for the group. More plosives were present for acoustic analyses (91.6%) than were fricatives (78.4%). Duration for the speech intelligibility sentences averaged 2572.3 msec. Communication breakdowns occurred on average 14.5% of the time involved in a language sample. Significant predictors of high levels of oral communication skills included higher nonverbal intelligence, gender, longer use of SPEAK processing strategy, a fully active electrode array, greater dynamic range, and greater growth of loudness. The primary rehabilitative factors contributing to high levels of oral communication were an emphasis on oral-aural communication and classrooms that emphasized dependence on speech and listening.

CONCLUSIONS

Speech production performance in children with cochlear implants is influenced by nonverbal intelligence, gender, implant characteristics including the length of time using the newest speech processing strategies, and educational programs emphasizing oral-aural communication. Factors previously thought to be major contributors to speech production performance, such as age of onset of deafness and age of implantation, did not appear to play significant roles in predicting levels of speech production performance.

Neurotrophic factor intervention restores auditory function in deafened animals

A primary cause of deafness is damage of receptor cells in the inner ear. Clinically, it has been demonstrated that effective functionality can be provided by electrical stimulation of the auditory nerve, thus bypassing damaged receptor cells. However, subsequent to sensory cell loss there is a secondary degeneration of the afferent nerve fibers, resulting in reduced effectiveness of such cochlear prostheses. The effects of neurotrophic factors were tested in a guinea pig cochlear prosthesis model. After chemical deafening to mimic the clinical situation, the neurotrophic factors brain-derived neurotrophic factor and an analogue of ciliary neurotrophic factor were infused directly into the cochlea of the inner ear for 26 days by using an osmotic pump system. An electrode introduced into the cochlea was used to elicit auditory responses just as in patients implanted with cochlear prostheses. Intervention with brain-derived neurotrophic factor and the ciliary neurotrophic factor analogue not only increased the survival of auditory spiral ganglion neurons, but significantly enhanced the functional responsiveness of the auditory system as measured by using electrically evoked auditory brainstem responses. This demonstration that neurotrophin intervention enhances threshold sensitivity within the auditory system will have great clinical importance for the treatment of deaf patients with cochlear prostheses. The findings have direct implications for the enhancement of responsiveness in deafferented peripheral nerves.

Speech, Language, and Reading Skills After Early Cochlear Implantation

OBJECTIVE

To examine whether age at cochlear implantation or duration of implant use is associated with speech, language, and reading skills exhibited at age 8 to 9 years in children who underwent implantation by age 5 years.

DESIGN

Performance outcomes in speech perception, speech production, language, and reading were examined in terms of the age at which children first received a cochlear implant (2, 3, or 4 years), the age they received an updated (Spectra) processor, and the duration of use of an implant and an updated processor.

SETTING

Data collection was conducted at summer research camps held over 4 consecutive years to maximize the number of children available at a specific age (8-9 years). Children were tested individually by experienced examiners, and their parents and therapists provided background and educational history information.

PARTICIPANTS

A total of 181 children from 33 different states and 5 Canadian provinces who received a cochlear implant by age 5 years were tested. A subsample of 133 children with performance IQ scores of 80 or greater and onset of deafness at birth were selected for the age-at-implantation analysis. Another subsample of 39 children with deafness acquired by age 3 years was also examined.

OUTCOME MEASURES

A battery of tests of speech perception, speech production, language, and reading was administered to each child and reduced to a single factor score for each skill.

RESULTS

Correlation coefficients between age at implantation and duration of use did not reach significance for any of the outcome skills measured. Age at which the updated speech processor (Spectra) was fitted was significantly related to speech production outcome (earlier use of an updated processor was associated with greater speech intelligibility) but not to any other skill area. However, more of the children who underwent implantation at age 2 years (43%) achieved combined speech and language skills commensurate with their age-matched peers with normal hearing than did children who underwent implantation at age 4 years (16%). Furthermore, normal speech and language skills were documented in 80% of children who lost hearing after birth and who underwent implantation within a year of onset of deafness.

CONCLUSIONS

For children who receive a cochlear implant between the ages of 2 and 4 years, early cochlear implantation does not ensure better speech perception, speech production, language, or reading skills. However, greater speech and language proficiency may be expected from children who exhibit normal hearing for even a brief period after birth and receive a cochlear implant shortly after losing their hearing. Further research examining the benefits of cochlear implantation before age 2 years will help families and clinicians better understand the time-sensitive nature of the decision to conduct cochlear implant surgery.

Speech understanding in quiet and noise in bilateral users of the MED-EL COMBI 40/40+ cochlear implant system

OBJECTIVE

The purpose of the study was to investigate speech understanding in quiet and noise in subjects bilaterally implanted with multi-channel cochlear implants.

DESIGN

Nine adults bilaterally implanted with MED-EL implants were included in the study. The subjects were tested in three conditions: with both implants, with the right implant only, and with the left implant only. Speech tests included monosyllables in quiet and sentences in noise (10 dB signal to noise ratio). Speech was presented from the front, and noise was presented from either 90 degrees or 270 degrees azimuth.

RESULTS

All subjects reported benefit from bilateral stimulation. Speech scores for all subjects were higher with bilateral than with unilateral stimulation. The average score across subjects for sentence understanding was 31.1 percentage points higher with both cochlear implants compared with the cochlear implant ipsilateral to the noise, and 10.7 percentage points higher with both cochlear implants compared with the cochlear implant contralateral to the noise. The average score for recognition of monosyllabic words was 18.7 percentage points higher with both cochlear implants than with one cochlear implant. All of these differences in average scores were significant at the 5% level.

CONCLUSIONS

Bilateral cochlear implantation provides a significant benefit in speech understanding in both quiet and noise.

The effect of age at cochlear implant initial stimulation on expressive language growth in infants and toddlers

This study examined the growth of expressive language skills in children who received cochlear implants (CIs) in infancy. Repeated language measures were gathered from 29 children who received CIs between 10 and 40 months of age. Both cross-sectional and growth curve analyses were used to assess the relationship between expressive language outcomes and CI experience. A beneficial effect of earlier implantation on expressive language growth was found. Growth curve analysis showed that growth was more rapid in children implanted as infants than those implanted as toddlers. Age at initial stimulation accounted for 14.6% of the variance of the individual differences in expressive language growth rates.

Speech perception and cortical event related potentials in children with auditory neuropathy

OBJECTIVES

1) To investigate the unaided and aided speech perception abilities of children with auditory neuropathy (AN) and to compare their performance to children with sensorineural hearing loss. 2) To establish whether cortical event related potentials (ERPs) could be recorded in children with AN, and to determine the relationship between the presence of these responses and speech perception.

DESIGN

Unaided and aided speech perception assessments (PBK words), and cortical-ERP testing was carried out in a group of 18 children with AN. Data also were obtained from a cohort of age and hearing level matched children with sensorineural hearing loss.

RESULTS

The speech perception performance of the 15 children with AN able to complete a PBK-word assessment, fell into two distinct categories. The children either showed no open-set speech perception ability (7/15 cases), or performance levels similar to their sensorineural counterparts (8/15 cases). Approximately 50% of children with AN showed ERPs of normal latency, amplitude and morphology. In all cases, response presence (at normal latencies) was consistent with reasonable speech perception ability, and response absence was consistent with negligible speech perception.

CONCLUSIONS

In approximately 50% of children with auditory neuropathy, the provision of amplification results in significant open-set speech perception improvements. The results confirm the previously published reports that speech perception ability cannot be reliably estimated from the behavioral audiogram in children with AN. Obligatory ERP test results may offer a means of predicting perceptual skills in newly diagnosed youngsters as the presence of ERPs (with age-appropriate latency and morphology) was correlated with significant open set speech perception abilities and amplification benefit. The absence of the ERP in contrast, indicated profound hearing disability evidenced by profound hearing loss and/or extremely poor speech perception.

Meta-analysis of quality-of-life improvement after cochlear implantation and associations with speech recognition abilities

OBJECTIVES

Determine the impact of cochlear implantation on quality of life (QOL) and determine the correlation between QOL and speech recognition ability.

STUDY DESIGN

Two authors independently searched PubMed, Medline, Scopus, and the Cumulative Index to Nursing and Allied Health Literature to identify studies reporting hearing-specific or cochlear implant (CI)-specific QOL outcomes before and after cochlear implantation, and studies reporting correlations between QOL and speech recognition after cochlear implantation. Data from the included articles were obtained independently by two authors. Standardized mean difference (SMD) for each measure and pooled effects were determined to assess improvement in QOL before and after cochlear implantation.

RESULTS

From 14 articles with 679 CI patients who met the inclusion criteria, pooled analyses of all hearing-specific QOL measures revealed a very strong improvement in QOL after cochlear implantation (SMD = 1.77). Subset analysis of CI-specific QOL measures also showed very strong improvement (SMD = 1.69). Thirteen articles with 715 patients met the criteria to evaluate associations between QOL and speech recognition. Pooled analyses showed a low positive correlation between hearing-specific QOL and word recognition in quiet (r = 0.213), sentence recognition in quiet (r = 0.241), and sentence recognition in noise (r = 0.238). Subset analysis of CI-specific QOL showed similarly low positive correlations with word recognition in quiet (r = 0.213), word recognition in noise (r = 0.241), and sentence recognition in noise (r = 0.255).

CONCLUSIONS

Using hearing-specific and CI-specific measures of QOL, patients report significantly improved QOL after cochlear implantation. However, widely used clinical measures of speech recognition are poor predictors of patient-reported QOL with CIs. Laryngoscope, 128:982-990, 2018.