Temporal Modulation Detection in Children and Adults With Cochlear Implants: Initial Results.

OBJECTIVES: The auditory experience of early deafened pediatric cochlear implant (CI) users is different from that of postlingually deafened adult CI users due to disparities in the developing auditory system. It is therefore expected that the auditory psychophysical capabilities between these two groups would differ. In this study, temporal resolving ability was investigated using a temporal modulation detection task to compare the performance outcomes between these two groups. DESIGN: The minimum detectable modulation depth of amplitude modulated broadband noise at 100 Hz was measured for 11 early deafened children with a CI and 16 postlingually deafened adult CI users. RESULTS: Amplitude modulation detection thresholds were significantly lower (i.e., better) for the pediatric CI users than for the adult CI users. Within each group, modulation detection thresholds were not significantly associated with chronologic age, age at implantation, or years of CI experience. CONCLUSIONS: Early implanted children whose auditory systems develop in response to electric stimulation demonstrate better temporal resolving abilities than postlingually deafened adult CI users. This finding provides evidence to suggest that early implanted children might benefit from sound coding strategies emphasizing temporal information.

Early Communication Development of Children with Auditory Brainstem Implants.

The auditory brainstem implant (ABI) is an auditory sensory device that is surgically placed on the cochlear nucleus of the brainstem for individuals who are deaf but unable to benefit from a cochlear implant (CI) due to anatomical abnormalities of the cochlea and/or eighth nerve, specific disease processes, or temporal bone fractures. In the United States, the Food and Drug Administration has authorized a Phase I clinical trial to determine safety and feasibility of the ABI in up to 10 eligible young children who are deaf and either derived no benefit from the CI or were anatomically unable to receive a CI. In this paper, we describe the study protocol and the children who have enrolled in the study thus far. In addition, we report the scores on speech perception, speech production, and language (spoken and signed) for five children with 1-3 years of assessment post-ABI activation. To date, the results indicate that spoken communication skills are slow to develop and that visual communication remains essential for post-ABI intervention.

Assessing the Benefit-Risk Profile for Pediatric Implantable Auditory Prostheses.

BACKGROUND/AIMS: Children with congenital cochleovestibular abnormalities associated with profound hearing loss have few treatment options if cochlear implantation does not yield benefit. An alternative is the auditory brainstem implant (ABI). Regulatory authority device approvals currently include a structured benefit-risk assessment. Such an assessment, for regulatory purposes or to guide clinical decision making, has not been published, to our knowledge, for the ABI and may lead to the design of a research program that incorporates regulatory authority, family, and professional input. METHODS: Much structured benefit-risk research has been conducted in the context of drug trials; here we apply this approach to device studies. A qualitative framework organized benefit (speech recognition, parent self-report measures) and risk (surgery- and device-related) information to guide the selection of candidates thought to have potential benefit from ABI. RESULTS: Children with cochleovestibular anatomical abnormalities are challenging for appropriate assessment of candidacy for a cochlear implant or an ABI. While the research is still preliminary, children with an ABI appear to slowly obtain benefit over time. A team of professionals, including audiological, occupational, and educational therapy, affords maximum opportunity for benefit. CONCLUSIONS: Pediatric patients who have abnormal anatomy and are candidates for an implantable auditory prosthetic require an individualized, multisystems review. The qualitative benefit-risk assessment used here to characterize the condition, the medical need, potential benefits, risks, and risk management strategies has revealed the complex factors involved. After implantation, continued team support for the family during extensive postimplant therapy is needed to develop maximum auditory skill benefit.

Spectral-Temporal Modulated Ripple Discrimination by Children With Cochlear Implants.

OBJECTIVES: A postlingually implanted adult typically develops hearing with an intact auditory system, followed by periods of deafness (or near deafness) and adaptation to the implant. For an early implanted child whose brain is highly plastic, the auditory system matures with consistent input from a cochlear implant. It is likely that the auditory system of early implanted cochlear implant users is fundamentally different than postlingually implanted adults. The purpose of this study is to compare the basic psychophysical capabilities and limitations of these two populations on a spectral resolution task to determine potential effects of early deprivation and plasticity. DESIGN: Performance on a spectral resolution task (Spectral-temporally Modulated Ripple Test [SMRT]) was measured for 20 bilaterally implanted, prelingually deafened children (between 5 and 13 years of age) and 20 hearing children within the same age range. Additionally, 15 bilaterally implanted, postlingually deafened adults, and 10 hearing adults were tested on the same task. Cochlear implant users (adults and children) were tested bilaterally, and with each ear alone. Hearing listeners (adults and children) were tested with the unprocessed SMRT and with a vocoded version that simulates an 8-channel cochlear implant. RESULTS: For children with normal hearing, a positive correlation was found between age and SMRT score for both the unprocessed and vocoded versions. Older hearing children performed similarly to hearing adults in both the unprocessed and vocoded test conditions. However, for children with cochlear implants, no significant relationship was found between SMRT score and chronological age, age at implantation, or years of implant experience. Performance by children with cochlear implants was poorer than performance by cochlear implanted adults. It was also found that children implanted sequentially tended to have better scores with the first implant compared with the second implant. This difference was not observed for adults. An additional finding was that SMRT score was negatively correlated with age for adults with implants. CONCLUSIONS: Results from this study suggest that basic psychophysical capabilities of early implanted children and postlingually implanted adults differ when assessed in the sound field using their personal implant processors. Because spectral resolution does not improve with age for early implanted children, it seems likely that the sparse representation of the signal provided by a cochlear implant limits spectral resolution development. These results are supported by the finding that postlingually implanted adults, whose auditory systems matured before the onset of hearing loss, perform significantly better than early implanted children on the spectral resolution test.

Initial Results of a Safety and Feasibility Study of Auditory Brainstem Implantation in Congenitally Deaf Children.

OBJECTIVE: To determine the safety and feasibility of the auditory brainstem implant (ABI) in congenitally deaf children with cochlear aplasia and/or cochlear nerve deficiency. STUDY DESIGN: Phase I feasibility clinical trial of surgery in 10 children, ages 2 to 5 years, over a 3-year period. SETTING: Tertiary children's hospital and university-based pediatric speech/language/hearing center. INTERVENTION(S): ABI implantation and postsurgical programming. MAIN OUTCOME MEASURE(S): The primary outcome measure is the number and type of adverse events during ABI surgery and postsurgical follow-up, including behavioral mapping of the device. The secondary outcome measure is access to and early integration of sound. RESULTS: To date, nine children are enrolled. Five children have successfully undergone ABI surgery and postoperative behavioral programming. Three children were screen failures, and one child is currently undergoing candidacy evaluation. Expected adverse events have been documented in three of the five children who received the ABI. One child experienced a cerebral spinal fluid leak, which resolved with lumbar drainage. One child demonstrated vestibular side effects during device programming, which resolved by deactivating one electrode. One child experienced postoperative vomiting resulting in an abdominal radiograph. Four children have completed their 1-year follow-up and have speech detection thresholds of 30 to 35 dB HL. Scores on the IT-MAIS/MAIS range from 8 to 31 (out of a total of 40), and the children are demonstrating some ability to discriminate between closed-sets words that differ by number of syllables (pattern perception). CONCLUSION: ABI surgery and device activation seem to be safe and feasible in this preliminary cohort.

The Acoustic Change Complex in Young Children with Hearing Loss: A Preliminary Study.

The acoustic change complex (ACC) is a cortical auditory evoked potential elicited in response to a change in an ongoing sound. The ACC may have promise for assessing speech perception in infants and toddlers. In this preliminary study, the ACC was elicited in adults and young children in response to changes in speech stimuli representing vowel height /u/-/a/ and vowel place /u/-/i/ contrasts. The participants were adults with normal hearing (n = 3), children with normal hearing (n = 5), and children with mild to moderately severe bilateral sensorineural hearing loss (n = 5). The children with hearing loss were hearing aid users. The ages ranged from 2 years 3 months to 6 years 3months for the children and 44 to 55 years for the adults. Robust P1-N1-P2 responses were present for the adults and P1-N2 responses were present for all but the youngest child with hearing loss. The ACC response for the vowel place contrast was less robust than that for the vowel height contrast in one child with substantial hearing loss. The findings from this preliminary study support the conclusion that the ACC can be used successfully to assess auditory resolution in most young children.

Studies in pediatric hearing loss at the House Research Institute.

Three clinical research projects are described that are relevant to pediatric hearing loss. The three projects fall into two distinct areas. The first area emphasizes clinical studies that track developmental outcomes in children with hearing loss; one project is specific to cochlear implants and the other to hearing aids. The second area addresses speech perception test development for very young children with hearing loss. Although these two lines of research are treated as separate areas, they begin to merge as new behavioral tests become useful in developing protocols for contemporary studies that address longitudinal follow-up of children with hearing loss.

An on-line imitative test of speech-pattern contrast perception (OlimSpac): developmental effects in normally hearing children.

PURPOSE: The goal was to assess the effects of maturation and phonological development on performance, by normally hearing children, on an imitative test of auditory capacity (On-Line Imitative Test of Speech-Pattern Contrast Perception [OlimSpac]; Boothroyd, Eisenberg, & Martinez, 2006; Eisenberg, Martinez, & Boothroyd, 2003, 2007). METHOD: Thirty-four hearing children (aged between 1;8 [years;months] and 6;7) were asked to imitate nonword utterances. Responses were evaluated by a blinded listener in an 8-alternative forced-choice task, giving information on the children's ability to convey, by imitation, information about 6 binary phonemic contrasts. RESULTS: Four children declined participation. Among 30 children aged 2;7 or older, performance improved significantly with age and varied with contrast. All children 3 years of age or older attained passing scores (7 or 8 correct responses in 8 binary trials) on at least 5 of the 6 contrasts. Post-alveolar consonant place was the contrast most often failed. CONCLUSIONS: When evaluated on a pass/fail basis, normally hearing children 3 years of age or older are likely to demonstrate auditory perception of most phonemic contrasts using this imitative test. Phonological development and other task-related factors have only a modest effect on performance by normally hearing children after 3 years of age. The effects of hearing loss, hearing age, sensory assistance, and listening experience in children with hearing loss remain to be determined.

Relationships between speech perception abilities and spoken language skills in young children with hearing loss.

The goal of this study was to examine the relationships between scores obtained from measures of speech perception and language in a group of young children with hearing loss (HL). Eighteen children (mean age = 4.3 years) and their mothers participated in this study. Speech perception was measured using the online imitative test of speech pattern contrast perception (OLIMSPAC). Standardized language age equivalent scores were obtained using the Reynell developmental language scales-III. Number of word tokens, word types, and mean length of utterance (MLU) were extracted from the children's spontaneous language samples. Significant positive relationships were observed between children's OLIMSPAC scores and both standardized language scores (r ranging from 0.60 to 0.69; p <0.01) and all measures derived from children's spontaneous language samples (r ranging from 0.80 to 0.86; p<0.01). After controlling for child age, OLIMSPAC scores explained 34.1% of the variance in children's MLU. Using a new speech perception measure with reduced language demands, strong positive correlations were evident between speech perception and language skills for a young group of children with HL.

Comprehensive evaluation of a child with an auditory brainstem implant.

OBJECTIVE: We had an opportunity to evaluate an American child whose family traveled to Italy to receive an auditory brainstem implant (ABI). The goal of this evaluation was to obtain insight into possible benefits derived from the ABI and to begin developing assessment protocols for pediatric clinical trials. STUDY DESIGN: Case study. SETTING: Tertiary referral center. PATIENT: Pediatric ABI Patient 1 was born with auditory nerve agenesis. Auditory brainstem implant surgery was performed in December, 2005, in Verona, Italy. The child was assessed at the House Ear Institute, Los Angeles, in July 2006 at the age of 3 years 11 months. Follow-up assessment has continued at the HEAR Center in Birmingham, Alabama. INTERVENTION: Auditory brainstem implant. MAIN OUTCOME MEASURES: Performance was assessed for the domains of audition, speech and language, intelligence and behavior, quality of life, and parental factors. RESULTS: Patient 1 demonstrated detection of sound, speech pattern perception with visual cues, and inconsistent auditory-only vowel discrimination. Language age with signs was approximately 2 years, and vocalizations were increasing. Of normal intelligence, he exhibited attention deficits with difficulty completing structured tasks. Twelve months later, this child was able to identify speech patterns consistently; closed-set word identification was emerging. These results were within the range of performance for a small sample of similarly aged pediatric cochlear implant users. CONCLUSION: Pediatric ABI assessment with a group of well-selected children is needed to examine risk versus benefit in this population and to analyze whether open-set speech recognition is achievable.

Assessing auditory capabilities in young children.

OBJECTIVE: Early detection of hearing loss in infants and toddlers has created a need for age-appropriate tests that assess auditory perceptual capabilities. This article describes a progressive test battery we have developed to evaluate phonetic contrast perception, phoneme recognition, and word recognition in children 6 months to 5 years. This battery is part of a clinical research protocol designed to track auditory development in this population. METHODS: The progressive test battery originated from a model of auditory perceptual development to assess phonetic discrimination and word recognition. Phonetic discrimination is evaluated using the Battery of Auditory Speech Perception Tests for Infants and Toddlers (BATIT). The BATIT is composed of four measures (VRASPAC, PLAYSPAC, OLIMSPAC, and VIDSPAC) intended to assess the child's ability to distinguish between phonologically significant contrasts using developmentally appropriate tasks. Designed for children aged 6 months and up, performance is represented either by percent correct or by the level of confidence that the child's responses are not random. Phoneme and word recognition are assessed in children 4 years and older using lists of consonant-vowel-consonant (CVC) phonemes in words and lexically controlled words both in and out of sentence context (LEXSEN). RESULTS: Cross-sectional data show that children with normal hearing may be assessed by the age of 7 months on VRASPAC; by 3 years on PLAYSPAC and OLIMSPAC; and by 4-5 years on VIDSPAC, CVC phonemes in words, and LEXSEN words in isolation and in sentences. Data from infants with hearing loss show that VRASPAC is sensitive to degree of hearing loss, but performance with normally hearing children declines after 12 months of age. CONCLUSION: Assessment of phonetic discrimination and word recognition is, for the most part, attainable in young children using a progressive test battery, but none of the tests used here is effective between 1 and 3 years of age. Continued development will be required to fill this gap and to separate auditory from non-auditory influences on performance.

Speech recognition at 1-year follow-up in the childhood development after cochlear implantation study: Methods and preliminary findings.

The Childhood Development after Cochlear Implantation (CDaCI) study is a longitudinal multicenter investigation designed to identify factors influencing spoken language in young deaf children with cochlear implants. Normal-hearing peers serve as controls. As part of a comprehensive evaluation battery, a speech recognition hierarchy was designed to assess how well these children recognize speech stimuli across developmental stages. Data were analyzed for the earliest measures in 42 pairs of children reaching 1 year of follow-up. A number of children in the cochlear implant group who met criteria for testing approached levels of performance similar to the normal-hearing controls, and some could identify sentences in competition. These results demonstrate the responsiveness of the speech recognition hierarchy in tracking emergent skills from a sample of the CDaCI cohort.

Clinical performance of children following revision surgery for a cochlear implant.

OBJECTIVES: The purpose of this study was to describe the causes for revision surgery and to compare clinical performance before and after surgery in children who required electrode reinsertion. STUDY DESIGN AND SETTINGS: Soundfield thresholds and speech recognition scores were compared before device failure and following electrode reinsertion. Temporal bones from a deceased adult implant user who underwent bilateral revision implantation were analyzed. RESULTS: Histopathology in the adult temporal bones revealed new bone formation in the scala tympani and substantially reduced spiral ganglion counts, with open-set speech recognition realized. Of 28 children undergoing revision surgery, 18 required electrode reinsertion. With the exception of 1 patient with severe cochlear malformation, new electrode arrays were fully inserted without difficulty. Clinical outcomes between pre-device failure and post-electrode reinsertion did not differ statistically. CONCLUSION AND SIGNIFICANCE: Electrode reinsertion is technically feasible in the pediatric population. The majority of children recover their prerevision clinical performance. EBM RATING: C-4.

Spoken word recognition development in children with residual hearing using cochlear implants and hearing AIDS in opposite ears.

OBJECTIVE: With broadening candidacy criteria for cochlear implantation, a greater number of pediatric candidates have usable residual hearing in their nonimplanted ears. This population potentially stands to benefit from continued use of conventional amplification in their nonimplanted ears. The purposes of this investigation were to evaluate whether children with residual hearing in their nonimplanted ears benefit from bilateral use of cochlear implants and hearing aids and to investigate the time course of adaptation to combined use of the devices together. DESIGN: Pediatric cochlear implant recipients with severe sensorineural hearing loss in their nonimplanted ears served as participants. Ten children continued to use hearing aids in their nonimplanted ears after cochlear implantation; 12 children used their cochlear implants exclusively. Participants were tested longitudinally on spoken word recognition measures at 6-month intervals. The children who continued wearing hearing aids were tested in three sensory aid conditions: cochlear implants alone, hearing aids alone, and cochlear implants in conjunction with hearing aids. The children who did not continue hearing aid use were tested after surgery in their only aided condition, cochlear implant alone. RESULTS: The results suggest that children with severe hearing loss who continued using hearing aids in their nonimplanted ears benefited from combining the acoustic input received from a hearing aid with the input received from a cochlear implant, particularly in background noise. However, this benefit emerged with experience. CONCLUSIONS: Our findings suggest that it is appropriate to encourage pediatric cochlear implant recipients with severe hearing loss to continue wearing an appropriately fitted hearing aid in the nonimplanted ear to maximally benefit from bilateral stimulation.