Electrical stimulation from a cochlear implant can spread beyond the auditory nerve. The aims of ... more Electrical stimulation from a cochlear implant can spread beyond the auditory nerve. The aims of this study were to accurately measure facial nerve stimulation in pediatric implant users and to determine the characteristics and incidence of this unwanted activity. Part A consisted of a prospective study of a randomized sample of 44 pediatric implant users. Part B consisted of a retrospective analysis of 121 children with previously recorded electrically evoked auditory brainstem responses (EABR). Responses were evoked by 3 electrodes along the implant array in three groups of children: 1) postmeningitic, 2) abnormal cochlea, and 3) neither. Intraoperative measures were obtained under anesthesia; all other recordings were completed in awake children. Intraoperative recordings revealed large nonauditory responses in a number of channels, including the midline EABR. Under paralysis, these responses disappeared, and clear EABRs were recorded. Similarly, prospective postoperative electro...
International journal of pediatric otorhinolaryngology, 2000
Cochlear implants have enabled many children with severe to profound sensorineural hearing loss t... more Cochlear implants have enabled many children with severe to profound sensorineural hearing loss to develop speech perception skills. However, some children experience few gains while others develop high levels of speech perception. We identified potential factors contributing to poor performance with an implant by studying implanted children who do not develop functional speech perception. Five children were identified as developing no open-set word recognition skills after at least 2 years of implant use. This study group was compared to a randomly selected control group (n=10) and an age-matched control group (n=5). Pre-implant factors were examined using a Graded Profile Analysis and post-implant factors were assessed in a retrospective chart review. A greater number of pre-implant concerns were raised in the study group than in randomized controls (P<0.01). Chronological age and duration of deafness were pre-implant concerns in all study group subjects. A greater number of po...
Bilateral cochlear implants aim to provide hearing to both ears for children who are deaf and pro... more Bilateral cochlear implants aim to provide hearing to both ears for children who are deaf and promote binaural/spatial hearing. Benefits are limited by mismatched devices and unilaterally-driven development which could compromise the normal integration of left and right ear input. We thus asked whether children hear a fused image (ie. 1 vs 2 sounds) from their bilateral implants and if this &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;binaural fusion&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; reduces listening effort. Binaural fusion was assessed by asking 25 deaf children with cochlear implants and 24 peers with normal hearing whether they heard one or two sounds when listening to bilaterally presented acoustic click-trains/electric pulses (250 Hz trains of 36 ms presented at 1 Hz). Reaction times and pupillary changes were recorded simultaneously to measure listening effort. Bilaterally implanted children heard one image of bilateral input less frequently than normal hearing peers, particularly when intensity levels on each side were balanced. Binaural fusion declined as brainstem asymmetries increased and age at implantation decreased. Children implanted later had access to acoustic input prior to implantation due to progressive deterioration of hearing. Increases in both pupil diameter and reaction time occurred as perception of binaural fusion decreased. Results indicate that, without binaural level cues, children have difficulty fusing input from their bilateral implants to perceive one sound which costs them increased listening effort. Brainstem asymmetries exacerbate this issue. By contrast, later implantation, reflecting longer access to bilateral acoustic hearing, may have supported development of auditory pathways underlying binaural fusion. Improved integration of bilateral cochlear implant signals for children is required to improve their binaural hearing.
The Annals of otology, rhinology & laryngology. Supplement, 2002
Input to the central auditory system through a cochlear implant promotes psychophysical improveme... more Input to the central auditory system through a cochlear implant promotes psychophysical improvement of auditory skills. However, the developmental changes along the pathways have never been characterized in children with hearing loss who use implants. We aimed to measure auditory development in such children by using the electrically evoked auditory brain stem response (EABR). We made repeated measures of the EABR in 41 nonsedated children with implants before chronic stimulation and after 2, 6, and 12 months of consistent implant use. The results show that EABRs were present in all of the children even before chronic auditory stimulation, and that EABR wave latencies decreased from the time of initial activation throughout the first year of cochlear implant use. These findings reflect auditory development to the level of the midbrain as a result of the cochlear implant. The decreasing latencies likely reflect decreased neural conduction times at this level, in part because of incre...
Children require audible and comfortable stimulation from their cochlear implants immediately aft... more Children require audible and comfortable stimulation from their cochlear implants immediately after device activation. To accomplish this, a battery of objective measures may be needed that could include the electrically evoked stapedius reflex (ESR), compound action potential from the auditory nerve (ECAP), and/or auditory brain stem response (EABR). In the present study, the following specific research questions were asked: In children using cochlear implants, 1) Can the ECAP, EABR, and ESR be recorded at the time of cochlear implantation? 2) What is the feasibility of measuring the ECAP, EABR, and the ESR repeatedly without the use of sedation over the first year of implant use? 3) Do ECAP, EABR, and ESR thresholds or behavioral measures change over time? 4) What is the relation between ECAP, EABR, and ESR thresholds and behavioral measures of threshold and comfortably loud levels? In 68 children, ECAP, EABR, and ESR responses as well as behavioral measures of stimulation thresho...
International journal of pediatric otorhinolaryngology, 2012
Cochlear implantation is a successful method of auditory rehabilitation. This procedure has been ... more Cochlear implantation is a successful method of auditory rehabilitation. This procedure has been associated with facial nerve and vestibular end-organ stimulation suggesting potential for extra-cochlear stimulation. The objectives of this study were to investigate the potential relationship between cochlear implantation and seizure activity in the pediatric implant population. Local Research Ethics Board approval was obtained. The Hospital for Sick Children's Cochlear Implant Database from 1998 to 2011 was retrospectively reviewed. Based on a multidisciplinary team, patients who received a diagnosis of seizure disorder or had been investigated for seizure-like activity were identified and reviewed. Fifteen children from a group of 816 pediatric cochlear implant users were identified as having suspected seizure-like activity. Eventually 10 children were found to have seizures based on an evaluation by a pediatric neurologist and an electroencephalogram. Of these 10, only 3 childr...
Objective: To determine the relationship between ethnicity and mutations in the GJB2 and GJB6 gen... more Objective: To determine the relationship between ethnicity and mutations in the GJB2 and GJB6 genes in multi-cultural patients enrolled in a Canadian paediatric Cochlear Implant Program. Methods: Blood was analyzed from 65 paediatric cochlear implant users by direct sequencing of the coding region and intron/exon boundaries of the GBJ2 gene. Individuals heterozygous for one mutation in GJB2 or in whom mutations in GJB2 were not detected were analyzed for the common 342 kb deletion mutation D13S1830 in the GJB6 gene. Information regarding ethnicity of patients' families was obtained from patient records and/or interview. Results: GJB2 mutations were found in 36.9% of paediatric cochlear implant users tested. Nine different GJB2 mutations were identified among individuals from 14 different countries of origin. Seventy-eight percent of all identified pathogenic GJB2 mutations were 35delG. Biallelic GJB2 mutations were found in 16 cochlear implant users (66.7% of GJB2 mutations). Three novel GJB2 sequence changes were identified:
Although voice has been studied extensively in children who use cochlear implants (CIs), speech p... more Although voice has been studied extensively in children who use cochlear implants (CIs), speech production has not been studied in this population using the Motor Speech Profile. Whether children who receive CIs gain normal speech production abilities is unknown. To assess speech and articulation in deaf, long-term CI users who had undergone early unilateral cochlear implantation, compared with their normal-hearing peers. Cross-sectional study at a tertiary pediatric hospital of 16 children aged 8 to 17 years who had undergone early implantation, are longstanding users, and had excellent audiogram and speech perception scores. Results were compared with a historical pediatric normal-hearing group. Unilateral cochlear implantation. The Motor Speech Profile, an objective method for assessing motor speech in children. The CI users had normal articulation and timing but poorer than normal intonation stimulability, particularly frequency variability. Diadochokinesis rates were within the 95% confidence interval of age-matched pediatric norms for 11 of 16 (69%) and 11 of 15 (73%) children with CI when they were performing /pa/ and /pataka/ tasks, respectively. The magnitude and rate of the second formant transitions were within normal limits for 9 of 16 (56%) and 10 of 12 (83%) children, respectively. The variability in frequency and amplitude of intonation stimulability domains were within normal limits for 7 of 16 (44%) and 16 of 16 (100%) children, respectively. The syllabic rate and duration were both within normal limits for 14 of 16 children (88%). Despite significant improvements in speech after cochlear implantation, abnormalities remain, particularly in frequency variability. Such deviations can present as a decreased expression of emotion in speech and likely reflects decreased auditory frequency resolution provided by the CI. These deficits have been the focus of ongoing work to advance CI technologies and speech-processing strategies.
Objectives/Hypothesis: Long term taste dysfunction after otologic surgery has never been characte... more Objectives/Hypothesis: Long term taste dysfunction after otologic surgery has never been characterized in children. The aim of this study is to determine the rates of gustatory dysfunction in normal and postotologic surgery in children.
Objectives/Hypothesis: Similarities between the peripheral auditory and vestibular systems sugges... more Objectives/Hypothesis: Similarities between the peripheral auditory and vestibular systems suggest that children with sensorineural hearing loss (SNHL) may demonstrate vestibular and balance impairments. This hypothesis was studied in 40 children with severe to profound SNHL and unilateral cochlear implants.
Objective/Hypothesis: It is reasonable to suppose that the pattern of sensorineural damage along ... more Objective/Hypothesis: It is reasonable to suppose that the pattern of sensorineural damage along the length of the cochlea depends on the etiology of a hearing loss (HL). In GJB2-related deafness, we hypothesize that gap junction deficits are uniformly distributed and will result in similar damage along the length of the cochlea as compared with non-GJB2 subjects. We assessed this by measuring patterns of neural activity and hearing from apical versus basal cochlear implant electrode regions. Study Design: This was a prospective, blind, controlled study. Methods: Blood from 301 pediatric cochlear implant users was analyzed for mutations in GJB2 by direct sequencing. After exclusion of patients with monoallelic GJB2 mutations, associated syndromes, or risk factors for HL that were not congenital, 39 children with biallelic GJB2 mutations and 58 without GJB2 mutations were evaluated. Hearing was measured before implantation at frequencies ranging from 250 Hz to 8 kHz. After implantation, neural activity at the apical and basal ends of the implanted array was measured using electrically evoked compound action potentials of the auditory nerve (ECAPs) and evoked stapedius reflexes (ESRs). Results: GJB2 and non-GJB2 groups were not significantly different with respect to sex, age at implantation, duration of auditory deprivation, hearing aid use, duration of aided hearing, ear implanted, implant model, or depth of insertion (P > .05). Children with GJB2-related HL had greater similarities between low-and high-frequency residual hearing and between neural activity electri-cally evoked at apical and basal regions of the cochlea as compared with children with non-GJB2-related HL who demonstrated larger deficits in basal regions. Conclusion: Results suggest more consistent spiral ganglion survival along the length of the cochlea in GJB2-related HL as compared with non-GJB2-related HL, which appears to involve a decreasing gradient of spiral ganglion survival from the apex to the base of the cochlea. Our findings support our premise that in GJB2-related HL, dysfunction of gap junctions likely occurs to a similar degree in the apical and basal regions of the cochlea. This knowledge might be used to customize implantable devices for patients with HL in the future.
Objectives/Hypothesis: To describe temporal bone findings using visual inspection and direct meas... more Objectives/Hypothesis: To describe temporal bone findings using visual inspection and direct measurement on computerized tomography (CT) in individuals with branchio-oto-renal syndrome (BOR). We ask if it is possible for the untrained observer to use a battery of CT observations as a tool in the overall evaluation of the BOR phenotype. Study Design: Retrospective evaluation of CT findings in individuals with a clinical diagnosis of BOR based on criteria derived from genotype-phenotype analyses. Methods: Prospective measurement of temporal bone CT imaging in 21 individuals (42 ears) with BOR and 21 normally hearing controls (21 ears) was performed. Thirty-nine aspects of each temporal bone were evaluated: 17 by direct measurement, 5 computed from direct measurement, and 17 by visual inspection. Thirty-eight recordings from each ear were made on axial section and 1 was made on coronal section. Results: Statistically significant differences were found between BOR and control groups in 30 of 39 categories (76.9%). The most common and easily identifiable characteristics of BOR by visual inspection were 1) hypoplastic apical turn of the cochlea, 2) facial nerve deviated to the medial side of the cochlea, 3) funnelshaped internal auditory canal, and 4) patulous eustachian tube. The embryological origin of temporal bone anomalies in BOR are described. Conclusions:
Objective: To describe temporal bone findings on computed tomography (CT) imaging in GJB2-related... more Objective: To describe temporal bone findings on computed tomography (CT) imaging in GJB2-related hearing loss (HL). We asked whether evaluation of the temporal bone is required in individuals with biallelic GJB2 mutations. Study Design: Randomized, blinded, controlled, prospective measurement. Methods: Blood from 264 pediatric cochlear implant users was analyzed for mutations in the GJB2 gene. Thirtysix aspects of the temporal bone on CT imaging were evaluated in 53 individuals (106 ears) with biallelic disease causing GJB2 mutations. A subset of patients was age matched and compared with normally hearing individuals. Subjects with biallelic GJB2 mutations were tested for mutations in the SLC26A4 gene to rule out Pendred syndrome as a confounding cause of large vestibular aqueduct syndrome. Results: Approximately 53% of ears of subjects (72% of subjects) with biallelic GJB2 mutations had at least one temporal bone anomaly. The most common findings were 1) dilated endolymphatic fossa (28%); 2) hypoplastic modiolus (25%); 3) large vestibular aqueduct (8%); 4) hypoplastic horizontal semicircular canal (8%); 5) hypoplastic cochlea (4%). Compared with normally hearing individuals, the GJB2 group had hypoplasia of the cochlear nerve canal, lateral semicircular canal vestibule, internal auditory canal (t tests, P < .001), and were 11 times more likely to have a hypoplastic modiolus. Dilated endolymphatic fossae were 1.4 times more common in the GJB2 group, and large vestibular aqueducts were 3 times more common in the GJB2 group, as compared with normally hearing controls. Conclusions: Temporal bone anomalies are common in GJB2-related HL, and imaging of the temporal bone should be included in routine evaluation of these individuals.
Assess vestibular and balance function in meningitis-induced profound sensorineural hearing loss ... more Assess vestibular and balance function in meningitis-induced profound sensorineural hearing loss (SNHL). Prospective cohort study. Tertiary pediatric referral center. Nine pediatric participant with profound SNHL after bacterial meningitis with (8) and without (1) unilateral Cochlear implant. Horizontal canal function in response to caloric and high-frequency rotation (0.25-5 Hz). Saccular function assessed by the vestibular evoked myogenic potential. Static and dynamic balance performance on the balance subset of the Bruininsk-Oseretsky Test of Motor Proficiency 2. Labyrinthine ossification on computed tomography preimplant, with follow-up imaging in a subset (n = 7). Horizontal canal function in response to caloric stimulation was abnormal in all children, with 5 of 8 demonstrating bilateral areflexia and 3 of 8 having asymmetric hypofunction with better function on the implanted side. In response to rotation, horizontal canal function was abnormal in all but 1 child (8 of 9). Saccular function, assessed by VEMP, was intact in most of the children (5 of 7). Static and dynamic balance (Bruininsk-Oseretsky Test of Motor Proficiency 2 scores) were significantly poorer in the meningitis group compared with both normal-hearing controls (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01) and children with SNHL of variable etiology and Cochlear implant (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01). Labyrinthine ossification was present in all cases, with variable extent, location, and progression. Vestibular function and balance are compromised in children with SNHL after meningitis. Whereas vestibular loss seems well compensated at low frequency through an overreliance on visual inputs, deficits surface during high-frequency rotation, particularly in dark. Saccular function seems less susceptible to damage from meningitis. Extent, location, and progression of ossification were variable. Despite profound dysfunction on objective testing, subjective limitations in functional balance were not reported, demonstrating the significant ability of children to compensate for even the most severe vestibular losses.
Journal of the American Academy of Audiology, 2008
Children with multiple disabilities account for a small percentage of implantees in a cochlear im... more Children with multiple disabilities account for a small percentage of implantees in a cochlear implant program, but they remain the most challenging group for which to predict benefit from the implant and for cooperation with habilitation postoperatively. To assess the relationship of pre-implant functional disabilities with postoperative speech perception scores and determine the feasibility of predicting outcome with a cochlear implant in a multiply disabled pediatric population. Retrospective cohort study. Sixty-six children with a cochlear implant and at least one additional disability. We retrospectively examined the relationship between pre-implant Graded Profile Analysis (GPA) scores and postimplant speech perception scores. A pre-implant functional disability score (based on the Battelle developmental screen) was applied to the same cohort of patients and its association with postimplant speech perception scores was examined. The functional disability score significantly predicted high (k &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 24) and low (k &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 7) speech perception scores (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001 and p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .0001) and had excellent discrimination ability (c statistic = 0.88 and 0.93 respectively). The GPA score was not significantly associated with speech perception scores (p = 0.519 and p = 0.146) and demonstrated no ability to discriminate postimplant speech perception scores in this implant population (c statistic = 0.49 and c = 0.57). Prediction of outcomes following cochlear implantation in multiply disabled children can be facilitated using this newly developed functional disability score as an adjunct to traditional candidacy assessments.
We have explored both the benefits and detriments of providing electrical input through a cochlea... more We have explored both the benefits and detriments of providing electrical input through a cochlear implant in one ear to the auditory system of young children. A cochlear implant delivers electrical pulses to stimulate the auditory nerve, providing children who are deaf with access to sound.The goals of implantation are to restrict reorganization of the deprived immature auditory brain and promote development of hearing and spoken language. It is clear that limiting the duration of deprivation is a key factor. Additional considerations are the onset, etiology, and use of residual hearing as each of these can have unique effects on auditory development in the pre-implant period. New findings show that many children receiving unilateral cochlear implants are developing mature-like brainstem and thalamo-cortical responses to sound with long term use despite these sources of variability; however, there remain considerable abnormalities in cortical function. The most apparent, determined by implanting the other ear and measuring responses to acute stimulation, is a loss of normal cortical response from the deprived ear. Recent data reveal that this can be avoided in children by early implantation of both ears simultaneously or with limited delay. We conclude that auditory development requires input early in development and from both ears.
Electrical stimulation from a cochlear implant can spread beyond the auditory nerve. The aims of ... more Electrical stimulation from a cochlear implant can spread beyond the auditory nerve. The aims of this study were to accurately measure facial nerve stimulation in pediatric implant users and to determine the characteristics and incidence of this unwanted activity. Part A consisted of a prospective study of a randomized sample of 44 pediatric implant users. Part B consisted of a retrospective analysis of 121 children with previously recorded electrically evoked auditory brainstem responses (EABR). Responses were evoked by 3 electrodes along the implant array in three groups of children: 1) postmeningitic, 2) abnormal cochlea, and 3) neither. Intraoperative measures were obtained under anesthesia; all other recordings were completed in awake children. Intraoperative recordings revealed large nonauditory responses in a number of channels, including the midline EABR. Under paralysis, these responses disappeared, and clear EABRs were recorded. Similarly, prospective postoperative electro...
International journal of pediatric otorhinolaryngology, 2000
Cochlear implants have enabled many children with severe to profound sensorineural hearing loss t... more Cochlear implants have enabled many children with severe to profound sensorineural hearing loss to develop speech perception skills. However, some children experience few gains while others develop high levels of speech perception. We identified potential factors contributing to poor performance with an implant by studying implanted children who do not develop functional speech perception. Five children were identified as developing no open-set word recognition skills after at least 2 years of implant use. This study group was compared to a randomly selected control group (n=10) and an age-matched control group (n=5). Pre-implant factors were examined using a Graded Profile Analysis and post-implant factors were assessed in a retrospective chart review. A greater number of pre-implant concerns were raised in the study group than in randomized controls (P<0.01). Chronological age and duration of deafness were pre-implant concerns in all study group subjects. A greater number of po...
Bilateral cochlear implants aim to provide hearing to both ears for children who are deaf and pro... more Bilateral cochlear implants aim to provide hearing to both ears for children who are deaf and promote binaural/spatial hearing. Benefits are limited by mismatched devices and unilaterally-driven development which could compromise the normal integration of left and right ear input. We thus asked whether children hear a fused image (ie. 1 vs 2 sounds) from their bilateral implants and if this &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;binaural fusion&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; reduces listening effort. Binaural fusion was assessed by asking 25 deaf children with cochlear implants and 24 peers with normal hearing whether they heard one or two sounds when listening to bilaterally presented acoustic click-trains/electric pulses (250 Hz trains of 36 ms presented at 1 Hz). Reaction times and pupillary changes were recorded simultaneously to measure listening effort. Bilaterally implanted children heard one image of bilateral input less frequently than normal hearing peers, particularly when intensity levels on each side were balanced. Binaural fusion declined as brainstem asymmetries increased and age at implantation decreased. Children implanted later had access to acoustic input prior to implantation due to progressive deterioration of hearing. Increases in both pupil diameter and reaction time occurred as perception of binaural fusion decreased. Results indicate that, without binaural level cues, children have difficulty fusing input from their bilateral implants to perceive one sound which costs them increased listening effort. Brainstem asymmetries exacerbate this issue. By contrast, later implantation, reflecting longer access to bilateral acoustic hearing, may have supported development of auditory pathways underlying binaural fusion. Improved integration of bilateral cochlear implant signals for children is required to improve their binaural hearing.
The Annals of otology, rhinology & laryngology. Supplement, 2002
Input to the central auditory system through a cochlear implant promotes psychophysical improveme... more Input to the central auditory system through a cochlear implant promotes psychophysical improvement of auditory skills. However, the developmental changes along the pathways have never been characterized in children with hearing loss who use implants. We aimed to measure auditory development in such children by using the electrically evoked auditory brain stem response (EABR). We made repeated measures of the EABR in 41 nonsedated children with implants before chronic stimulation and after 2, 6, and 12 months of consistent implant use. The results show that EABRs were present in all of the children even before chronic auditory stimulation, and that EABR wave latencies decreased from the time of initial activation throughout the first year of cochlear implant use. These findings reflect auditory development to the level of the midbrain as a result of the cochlear implant. The decreasing latencies likely reflect decreased neural conduction times at this level, in part because of incre...
Children require audible and comfortable stimulation from their cochlear implants immediately aft... more Children require audible and comfortable stimulation from their cochlear implants immediately after device activation. To accomplish this, a battery of objective measures may be needed that could include the electrically evoked stapedius reflex (ESR), compound action potential from the auditory nerve (ECAP), and/or auditory brain stem response (EABR). In the present study, the following specific research questions were asked: In children using cochlear implants, 1) Can the ECAP, EABR, and ESR be recorded at the time of cochlear implantation? 2) What is the feasibility of measuring the ECAP, EABR, and the ESR repeatedly without the use of sedation over the first year of implant use? 3) Do ECAP, EABR, and ESR thresholds or behavioral measures change over time? 4) What is the relation between ECAP, EABR, and ESR thresholds and behavioral measures of threshold and comfortably loud levels? In 68 children, ECAP, EABR, and ESR responses as well as behavioral measures of stimulation thresho...
International journal of pediatric otorhinolaryngology, 2012
Cochlear implantation is a successful method of auditory rehabilitation. This procedure has been ... more Cochlear implantation is a successful method of auditory rehabilitation. This procedure has been associated with facial nerve and vestibular end-organ stimulation suggesting potential for extra-cochlear stimulation. The objectives of this study were to investigate the potential relationship between cochlear implantation and seizure activity in the pediatric implant population. Local Research Ethics Board approval was obtained. The Hospital for Sick Children's Cochlear Implant Database from 1998 to 2011 was retrospectively reviewed. Based on a multidisciplinary team, patients who received a diagnosis of seizure disorder or had been investigated for seizure-like activity were identified and reviewed. Fifteen children from a group of 816 pediatric cochlear implant users were identified as having suspected seizure-like activity. Eventually 10 children were found to have seizures based on an evaluation by a pediatric neurologist and an electroencephalogram. Of these 10, only 3 childr...
Objective: To determine the relationship between ethnicity and mutations in the GJB2 and GJB6 gen... more Objective: To determine the relationship between ethnicity and mutations in the GJB2 and GJB6 genes in multi-cultural patients enrolled in a Canadian paediatric Cochlear Implant Program. Methods: Blood was analyzed from 65 paediatric cochlear implant users by direct sequencing of the coding region and intron/exon boundaries of the GBJ2 gene. Individuals heterozygous for one mutation in GJB2 or in whom mutations in GJB2 were not detected were analyzed for the common 342 kb deletion mutation D13S1830 in the GJB6 gene. Information regarding ethnicity of patients' families was obtained from patient records and/or interview. Results: GJB2 mutations were found in 36.9% of paediatric cochlear implant users tested. Nine different GJB2 mutations were identified among individuals from 14 different countries of origin. Seventy-eight percent of all identified pathogenic GJB2 mutations were 35delG. Biallelic GJB2 mutations were found in 16 cochlear implant users (66.7% of GJB2 mutations). Three novel GJB2 sequence changes were identified:
Although voice has been studied extensively in children who use cochlear implants (CIs), speech p... more Although voice has been studied extensively in children who use cochlear implants (CIs), speech production has not been studied in this population using the Motor Speech Profile. Whether children who receive CIs gain normal speech production abilities is unknown. To assess speech and articulation in deaf, long-term CI users who had undergone early unilateral cochlear implantation, compared with their normal-hearing peers. Cross-sectional study at a tertiary pediatric hospital of 16 children aged 8 to 17 years who had undergone early implantation, are longstanding users, and had excellent audiogram and speech perception scores. Results were compared with a historical pediatric normal-hearing group. Unilateral cochlear implantation. The Motor Speech Profile, an objective method for assessing motor speech in children. The CI users had normal articulation and timing but poorer than normal intonation stimulability, particularly frequency variability. Diadochokinesis rates were within the 95% confidence interval of age-matched pediatric norms for 11 of 16 (69%) and 11 of 15 (73%) children with CI when they were performing /pa/ and /pataka/ tasks, respectively. The magnitude and rate of the second formant transitions were within normal limits for 9 of 16 (56%) and 10 of 12 (83%) children, respectively. The variability in frequency and amplitude of intonation stimulability domains were within normal limits for 7 of 16 (44%) and 16 of 16 (100%) children, respectively. The syllabic rate and duration were both within normal limits for 14 of 16 children (88%). Despite significant improvements in speech after cochlear implantation, abnormalities remain, particularly in frequency variability. Such deviations can present as a decreased expression of emotion in speech and likely reflects decreased auditory frequency resolution provided by the CI. These deficits have been the focus of ongoing work to advance CI technologies and speech-processing strategies.
Objectives/Hypothesis: Long term taste dysfunction after otologic surgery has never been characte... more Objectives/Hypothesis: Long term taste dysfunction after otologic surgery has never been characterized in children. The aim of this study is to determine the rates of gustatory dysfunction in normal and postotologic surgery in children.
Objectives/Hypothesis: Similarities between the peripheral auditory and vestibular systems sugges... more Objectives/Hypothesis: Similarities between the peripheral auditory and vestibular systems suggest that children with sensorineural hearing loss (SNHL) may demonstrate vestibular and balance impairments. This hypothesis was studied in 40 children with severe to profound SNHL and unilateral cochlear implants.
Objective/Hypothesis: It is reasonable to suppose that the pattern of sensorineural damage along ... more Objective/Hypothesis: It is reasonable to suppose that the pattern of sensorineural damage along the length of the cochlea depends on the etiology of a hearing loss (HL). In GJB2-related deafness, we hypothesize that gap junction deficits are uniformly distributed and will result in similar damage along the length of the cochlea as compared with non-GJB2 subjects. We assessed this by measuring patterns of neural activity and hearing from apical versus basal cochlear implant electrode regions. Study Design: This was a prospective, blind, controlled study. Methods: Blood from 301 pediatric cochlear implant users was analyzed for mutations in GJB2 by direct sequencing. After exclusion of patients with monoallelic GJB2 mutations, associated syndromes, or risk factors for HL that were not congenital, 39 children with biallelic GJB2 mutations and 58 without GJB2 mutations were evaluated. Hearing was measured before implantation at frequencies ranging from 250 Hz to 8 kHz. After implantation, neural activity at the apical and basal ends of the implanted array was measured using electrically evoked compound action potentials of the auditory nerve (ECAPs) and evoked stapedius reflexes (ESRs). Results: GJB2 and non-GJB2 groups were not significantly different with respect to sex, age at implantation, duration of auditory deprivation, hearing aid use, duration of aided hearing, ear implanted, implant model, or depth of insertion (P > .05). Children with GJB2-related HL had greater similarities between low-and high-frequency residual hearing and between neural activity electri-cally evoked at apical and basal regions of the cochlea as compared with children with non-GJB2-related HL who demonstrated larger deficits in basal regions. Conclusion: Results suggest more consistent spiral ganglion survival along the length of the cochlea in GJB2-related HL as compared with non-GJB2-related HL, which appears to involve a decreasing gradient of spiral ganglion survival from the apex to the base of the cochlea. Our findings support our premise that in GJB2-related HL, dysfunction of gap junctions likely occurs to a similar degree in the apical and basal regions of the cochlea. This knowledge might be used to customize implantable devices for patients with HL in the future.
Objectives/Hypothesis: To describe temporal bone findings using visual inspection and direct meas... more Objectives/Hypothesis: To describe temporal bone findings using visual inspection and direct measurement on computerized tomography (CT) in individuals with branchio-oto-renal syndrome (BOR). We ask if it is possible for the untrained observer to use a battery of CT observations as a tool in the overall evaluation of the BOR phenotype. Study Design: Retrospective evaluation of CT findings in individuals with a clinical diagnosis of BOR based on criteria derived from genotype-phenotype analyses. Methods: Prospective measurement of temporal bone CT imaging in 21 individuals (42 ears) with BOR and 21 normally hearing controls (21 ears) was performed. Thirty-nine aspects of each temporal bone were evaluated: 17 by direct measurement, 5 computed from direct measurement, and 17 by visual inspection. Thirty-eight recordings from each ear were made on axial section and 1 was made on coronal section. Results: Statistically significant differences were found between BOR and control groups in 30 of 39 categories (76.9%). The most common and easily identifiable characteristics of BOR by visual inspection were 1) hypoplastic apical turn of the cochlea, 2) facial nerve deviated to the medial side of the cochlea, 3) funnelshaped internal auditory canal, and 4) patulous eustachian tube. The embryological origin of temporal bone anomalies in BOR are described. Conclusions:
Objective: To describe temporal bone findings on computed tomography (CT) imaging in GJB2-related... more Objective: To describe temporal bone findings on computed tomography (CT) imaging in GJB2-related hearing loss (HL). We asked whether evaluation of the temporal bone is required in individuals with biallelic GJB2 mutations. Study Design: Randomized, blinded, controlled, prospective measurement. Methods: Blood from 264 pediatric cochlear implant users was analyzed for mutations in the GJB2 gene. Thirtysix aspects of the temporal bone on CT imaging were evaluated in 53 individuals (106 ears) with biallelic disease causing GJB2 mutations. A subset of patients was age matched and compared with normally hearing individuals. Subjects with biallelic GJB2 mutations were tested for mutations in the SLC26A4 gene to rule out Pendred syndrome as a confounding cause of large vestibular aqueduct syndrome. Results: Approximately 53% of ears of subjects (72% of subjects) with biallelic GJB2 mutations had at least one temporal bone anomaly. The most common findings were 1) dilated endolymphatic fossa (28%); 2) hypoplastic modiolus (25%); 3) large vestibular aqueduct (8%); 4) hypoplastic horizontal semicircular canal (8%); 5) hypoplastic cochlea (4%). Compared with normally hearing individuals, the GJB2 group had hypoplasia of the cochlear nerve canal, lateral semicircular canal vestibule, internal auditory canal (t tests, P < .001), and were 11 times more likely to have a hypoplastic modiolus. Dilated endolymphatic fossae were 1.4 times more common in the GJB2 group, and large vestibular aqueducts were 3 times more common in the GJB2 group, as compared with normally hearing controls. Conclusions: Temporal bone anomalies are common in GJB2-related HL, and imaging of the temporal bone should be included in routine evaluation of these individuals.
Assess vestibular and balance function in meningitis-induced profound sensorineural hearing loss ... more Assess vestibular and balance function in meningitis-induced profound sensorineural hearing loss (SNHL). Prospective cohort study. Tertiary pediatric referral center. Nine pediatric participant with profound SNHL after bacterial meningitis with (8) and without (1) unilateral Cochlear implant. Horizontal canal function in response to caloric and high-frequency rotation (0.25-5 Hz). Saccular function assessed by the vestibular evoked myogenic potential. Static and dynamic balance performance on the balance subset of the Bruininsk-Oseretsky Test of Motor Proficiency 2. Labyrinthine ossification on computed tomography preimplant, with follow-up imaging in a subset (n = 7). Horizontal canal function in response to caloric stimulation was abnormal in all children, with 5 of 8 demonstrating bilateral areflexia and 3 of 8 having asymmetric hypofunction with better function on the implanted side. In response to rotation, horizontal canal function was abnormal in all but 1 child (8 of 9). Saccular function, assessed by VEMP, was intact in most of the children (5 of 7). Static and dynamic balance (Bruininsk-Oseretsky Test of Motor Proficiency 2 scores) were significantly poorer in the meningitis group compared with both normal-hearing controls (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01) and children with SNHL of variable etiology and Cochlear implant (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01). Labyrinthine ossification was present in all cases, with variable extent, location, and progression. Vestibular function and balance are compromised in children with SNHL after meningitis. Whereas vestibular loss seems well compensated at low frequency through an overreliance on visual inputs, deficits surface during high-frequency rotation, particularly in dark. Saccular function seems less susceptible to damage from meningitis. Extent, location, and progression of ossification were variable. Despite profound dysfunction on objective testing, subjective limitations in functional balance were not reported, demonstrating the significant ability of children to compensate for even the most severe vestibular losses.
Journal of the American Academy of Audiology, 2008
Children with multiple disabilities account for a small percentage of implantees in a cochlear im... more Children with multiple disabilities account for a small percentage of implantees in a cochlear implant program, but they remain the most challenging group for which to predict benefit from the implant and for cooperation with habilitation postoperatively. To assess the relationship of pre-implant functional disabilities with postoperative speech perception scores and determine the feasibility of predicting outcome with a cochlear implant in a multiply disabled pediatric population. Retrospective cohort study. Sixty-six children with a cochlear implant and at least one additional disability. We retrospectively examined the relationship between pre-implant Graded Profile Analysis (GPA) scores and postimplant speech perception scores. A pre-implant functional disability score (based on the Battelle developmental screen) was applied to the same cohort of patients and its association with postimplant speech perception scores was examined. The functional disability score significantly predicted high (k &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 24) and low (k &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 7) speech perception scores (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001 and p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .0001) and had excellent discrimination ability (c statistic = 0.88 and 0.93 respectively). The GPA score was not significantly associated with speech perception scores (p = 0.519 and p = 0.146) and demonstrated no ability to discriminate postimplant speech perception scores in this implant population (c statistic = 0.49 and c = 0.57). Prediction of outcomes following cochlear implantation in multiply disabled children can be facilitated using this newly developed functional disability score as an adjunct to traditional candidacy assessments.
We have explored both the benefits and detriments of providing electrical input through a cochlea... more We have explored both the benefits and detriments of providing electrical input through a cochlear implant in one ear to the auditory system of young children. A cochlear implant delivers electrical pulses to stimulate the auditory nerve, providing children who are deaf with access to sound.The goals of implantation are to restrict reorganization of the deprived immature auditory brain and promote development of hearing and spoken language. It is clear that limiting the duration of deprivation is a key factor. Additional considerations are the onset, etiology, and use of residual hearing as each of these can have unique effects on auditory development in the pre-implant period. New findings show that many children receiving unilateral cochlear implants are developing mature-like brainstem and thalamo-cortical responses to sound with long term use despite these sources of variability; however, there remain considerable abnormalities in cortical function. The most apparent, determined by implanting the other ear and measuring responses to acute stimulation, is a loss of normal cortical response from the deprived ear. Recent data reveal that this can be avoided in children by early implantation of both ears simultaneously or with limited delay. We conclude that auditory development requires input early in development and from both ears.
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