Karen A. Gordon

An Evoked Potential Study of the Developmental Time Course of the Auditory Nerve and Brainstem in Children Using Cochlear Implants

Central auditory responses to electrical stimulation from a cochlear implant were studied in 75 pre-lingually deafened children and 11 adults. Electrically evoked auditory brainstem response (EABR) latencies significantly decreased with duration of cochlear implant use and were not significantly affected by the age at implant activation. Significant decreases in early latency waves and interwaves occurred within the first 1–2 months of implant use, whereas longer term changes (6–12 months) were found for eV and eIII-eV, which measure activity in the more rostral brainstem. Comparisons to acoustically evoked auditory brainstem response (ABR) in children with normal hearing suggested shorter interwave EABR latencies, reflecting either distinct neural generators or increased neural synchrony, but similar rates of change in the later latency eV and eIII-eV with time in sound. In sum, normal-like development of the rostral auditory brainstem is promoted by cochlear implant use in children of a wide range of ages.

Recognition of Affective Speech Prosody and Facial Affect in Deaf Children with Unilateral Right Cochlear Implants

Cochlear implant (CI) devices provide the opportunity for children who are deaf to perceive sound by electrical stimulation of the auditory nerve, with the goal of optimizing oral communication. One part of oral communication concerns meaning, while another part concerns emotion: affective speech prosody, in the auditory domain, and facial affect, in the visual domain. It is not known whether childhood CI users can identify emotion in speech and faces, so we investigated speech prosody and facial affect in children who had been deaf from infancy and experienced CI users. METHOD: Study participants were 18 CI users (ages 7–13 years) who received right unilateral CIs and 18 age- and gender-matched controls. Emotion recognition in speech prosody and faces was measured by the Diagnostic Analysis of Nonverbal Accuracy. RESULTS: Compared to controls, children with right CIs could identify facial affect but not affective speech prosody. Age at test and time since CI activation were uncorrelated with overall outcome measures. CONCLUSION: Children with right CIs recognize emotion in faces but have limited perception of affective speech prosody.

Asymmetric Hearing During Development: The Aural Preference Syndrome and Treatment Options

Deafness affects ∼2 in 1000 children and is one of the most common congenital impairments. Permanent hearing loss can be treated by fitting hearing aids. More severe to profound deafness is an indication for cochlear implantation. Although newborn hearing screening programs have increased the identification of asymmetric hearing loss, parents and caregivers of children with single-sided deafness are often hesitant to pursue therapy for the deaf ear. Delayed intervention has consequences for recovery of hearing. It has long been reported that asymmetric hearing loss/single-sided deafness compromises speech and language development and educational outcomes in children. Recent studies in animal models of deafness and in children consistently show evidence of an “aural preference syndrome” in which single-sided deafness in early childhood reorganizes the developing auditory pathways toward the hearing ear, with weaker central representation of the deaf ear. Delayed therapy consequently compromises benefit for the deaf ear, with slow rates of improvement measured over time. Therefore, asymmetric hearing needs early identification and intervention. Providing early effective stimulation in both ears through appropriate fitting of auditory prostheses, including hearing aids and cochlear implants, within a sensitive period in development has a cardinal role for securing the function of the impaired ear and for restoring binaural/spatial hearing. The impacts of asymmetric hearing loss on the developing auditory system and on spoken language development have often been underestimated. Thus, the traditional minimalist approach to clinical management aimed at 1 functional ear should be modified on the basis of current evidence.

What is the optimal timing for bilateral cochlear implantation in children

Abstract Bilateral cochlear implants (CIs) have been provided to children who are deaf in both ears with intent to promote binaural hearing. If it is possible to establish binaural hearing with two CIs, these children would be able to make use of interaural level and timing differences to localize sound and to distinguish between sounds separated in space. These skills are central to the ability to attend to one particular sound amidst a number of sound sources. This may be particularly important for children because they are typically learning and interacting in groups. However, the development of binaural processing could be disrupted by effects of bilateral deafness, effects of unilateral CI use, or issues related to the childs age at onset of deafness and age at the time of the first and second cochlear implantation. This research aims to determine whether binaural auditory processing is affected by these variables in an effort to determine the optimal timing for bilateral cochlear implantation in children. It is now clear that the duration of bilateral deafness should be limited in children to restrict reorganization in the auditory thalamo-cortical pathways. It has also been shown that unilateral CI use can halt such reorganization to some extent and promote auditory development. At the same time, however, unilateral input might compromise the development of binaural processing if CIs are provided sequentially. Mismatches in responses from the auditory brainstem and cortex evoked by the first and second CI after a long period of unilateral CI use suggest asymmetry in the bilateral auditory pathways which is significantly more pronounced than in children receiving bilateral implants simultaneously. Moreover, behavioural responses to level and timing differences between implants suggest that these important binaural cues are not being processed normally by children who received a second CI after a long period of unilateral CI use and at older ages. In sum, there may be multiple sensitive periods in the developing auditory system, which must be considered when determining the optimal timing for bilateral cochlear implantation.

The role of a graded profile analysis in determining candidacy and outcome for cochlear implantation in children

Assessment of candidacy for cochlear implantation in children continues to present a challenge to cochlear implant programs. The efficacy of implantation depends on a number of factors and as a result a multidisciplinary approach has been adopted. At the Cochlear Implant Program at The Hospital for Sick Children, Toronto, we use a graded profile analysis (GPA) which has been adapted from the Childrens Implant Profile (CHIP) developed by Hellman (S.A. Hellman, P.M. Chute, R.E. Kretschmer, M.E., Nevins, S.C. Parisier, L.C. Thurston, The development of a Childrens Implant Profile, Am. Ann. Deaf. 136 (1991) 77-81). This structured assessment allows each potential candidate to be scored in each category of assessment giving a potential range of -14 to +14. In this retrospective study of 109 candidates we examine the relationship between GPA scores and decision to implant. For those patients who were implanted, the relationship between GPA score and speech perception outcomes was also evaluated. Three distinct groups of children emerged from the analysis. The first group had scores less than 5 and were not considered to be suitable for implantation. Within the second group who scored between 5 and 8, there was no clear relationship between decision to implant and score. The last group, who scored 9-14, was considered to be generally suitable for implantation provided that there were no medical contraindications and the parents consented to implantation. There was a significant association between rate of improvement of speech perception and GPA score. Those patients with scores of 9 to +14 improved at a faster rate than group 5-8 (P < 0.05). The implications of these findings are discussed.

Characterizing responses from auditory cortex in young people with several years of cochlear implant experience

OBJECTIVEnTo determine if cortical responses evoked by a cochlear implant in children who are deaf differ from normal and to characterize these differences in children who achieve good versus fair speech perception outcomes post-implantation.nnnMETHODSnLate latency-evoked potential responses were recorded at 28 scalp locations in 16 children who were deaf from infancy and experienced cochlear implant users. Speech perception measures indicated that 8 had good scores and 8 had fair scores. In each child, responses were evoked by 36ms electrical pulse trains delivered from a single-implant electrode at the apical and basal ends of the array and by 36ms tone bursts (0.5, 2, and 6kHz). Responses to the tone bursts were also recorded in 14 age-matched children with normal hearing.nnnRESULTSnWe found (1) a dominant positive wave in all implant users and (2) a larger than normal negative amplitude peak in users with fair speech perception scores which had similar scalp topography to N1 but did not show the expected changes in amplitude with stimulus frequency.nnnCONCLUSIONSnLate latency-evoked potential responses in children using cochlear implants reflect abnormal and/or immature patterns of cortical activity.nnnSIGNIFICANCEnLimitations in auditory skills with a cochlear implant in children may be due to developmental processes in the cortex which are either slow to mature or which mature abnormally.

Bilateral simultaneous cochlear implantation in children: Our first 50 cases

To assess the safety and surgical technique of bilateral simultaneous cochlear implantation in children.

Parental and program's decision making in paediatric simultaneous bilateral cochlear implantation: Who says no and why?

OBJECTIVEnTo evaluate initial candidacy for bilateral simultaneous cochlear implantation in children.nnnDESIGNnProspective case series.nnnSETTINGnTertiary academic pediatric hospital.nnnPARTICIPANTSnAs part of our research protocol all children eligible for cochlear implantation were assessed for suitability to receive a simultaneous bilateral implant. Over a 12-month period (January to December 2007) 78 children received a total of 95 cochlear implants. Children with sequential second implants (24), revision cases (4), and out of province recipients (4) were excluded. The remaining 46 patients were assessed for bilateral simultaneous implantation.nnnMAIN OUTCOME MEASURESnTeam/parental decision to proceed with bilateral simultaneous implantation.nnnRESULTSn17 children (37%) received simultaneous bilateral implants. 29 children (63%) were not considered suitable for simultaneous bilateral implantation. Reasons included developmental delay (10), residual borderline hearing in the second ear (9), parental/patient refusal (6), abnormally poor speech development for age (2), and abnormal cochlear anatomy precluding implantation (2). None were considered unsuitable for the more prolonged operative procedure on medical grounds.nnnCONCLUSIONSnAlthough bilateral implantation is thought to produce the optimal auditory outcome, not all patients are suitable, nor do all parents wish to proceed, when assessed for simultaneous implantation. Some of these patients are likely to be candidates for sequential bilateral implantation in due course.

Tinnitus is prevalent in children with cochlear implants

OBJECTIVESnTo explore the prevalence and the perceived impact of tinnitus in children using cochlear implants.nnnMETHODnCross-sectional study of implanted children attending a cochlear implant family event organized annually by our academic tertiary pediatric care center. Children were interviewed together with their parents, using open-questioning and structured interview qualitative methodologies. The main outcome measures were the prevalence of tinnitus and any impact of these symptoms.nnnRESULTSn40 children (age range: 3-15, mean: 7 years) and their families were interviewed. These included unilateral implantees (n=21), and bilateral implantees (n=19) whose two procedures were simultaneous (n=6), within 6-12 months (n=3), or >2 years apart (n=10). Tinnitus was reported by 38% (n=15). Tinnitus occurred most commonly in the implanted ear, when the implants were not in use (e.g. in bed at night). The children were generally untroubled by the tinnitus, although two reported difficulty sleeping. Tinnitus was most frequent in children aged 6-8 years (8/17, 47%), and in bilateral implantees with an inter-procedure delay of at least 2 years (6/10, 60%). Tinnitus was least reported in those implanted bilaterally simultaneously (1/6, 17%), and in those 5 years old or younger (3/11, 27%). No obvious relationship was identified between the prevalence of tinnitus and the etiology of deafness, age of implantation, or time elapsed since implantation.nnnCONCLUSIONSnTo our knowledge this is the first study to report the widespread prevalence of tinnitus in implanted children. Further work, particularly examining the effect of inter-implant delay on tinnitus in bilateral implantees, may contribute to our understanding of the neuronal plasticity after implantation.

Congenital cholesteatoma and cochlear implantation: Implications for management

Abstract Introduction Cholesteatoma is an uncommon condition that has occasionally been associated with cochlear implantation (CI). Cases of secondary acquired cholesteatoma have been described, in which intra-operative breech of the posterior canal wall is thought to be a contributing factor. Primary acquired cholesteatoma is not typically associated with congenital sensorineural hearing loss (SNHL) or CI in children. Congenital cholesteatoma is a rarer entity yet with an incidence in the literature of 2–4% of all cholesteatomas. We present lessons learned from our experience of congenital cholesteatoma in CI candidates. Methods Retrospective reviews of departmental CI and cholesteatoma databases in a tertiary/quaternary pediatric center were conducted. Cases of congenital cholesteatoma were identified. The proportion of congenital cholesteatoma cases in CI candidates was compared with number of acquired cholesteatoma. Optimum management of congenital cholesteatoma in CI candidates was reviewed. Results In our pediatric CI population, 2/794 patients (0.25%) were recognized as having a congenital cholesteatoma during their evaluation for CI. No cases of primary acquired cholesteatoma were identified in this population at presentation or at follow up to 18 years. Discussion The 0.25% incidence of congenital cholesteatoma in our population of CI patients is higher than expected of this rare condition. It is surprisingly common given the absence of any cases of primary acquired cholesteatoma, which is considerably more common even in the pediatric population. Both patients likely had an inherited form of hearing loss and a genetic contribution to the presence of congenital cholesteatoma cannot be excluded. The presence of congenital cholesteatoma has implications for the algorithm currently employed for the assessment of CI. We consider that surgery should be staged to ensure complete removal of the cholesteatoma before implantation. Thus bilateral CI should be provided sequentially rather than simultaneously in the presence of unilateral cholesteatoma.