Congenital Profound Sensorineural Hearing Loss Research Articles

Does cerebellar flocculus size affect subjective outcomes in pediatric auditory brainstem implantation

ObjectivesThe objectives of study was to 1) Describe relevant surgical anatomy in defining and accessing the lateral recess for placement of electrode, 2) Propose a working classification for grades of Flocculus; 3) To determine if different grades of cerebellar flocculus effects placement of ABI electrode and subjective outcomes in implantees. MethodsOur study was a prospective study, and comprised of cohort of 12 patients who underwent ABI surgery via retrosigmoid approach between 1 Jan 2012 to 31 Dec 2014. All children with congenital profound sensorineural hearing loss with either absent cochlea or cochlear nerve were included in the study. Relevant anatomy was noted. We also noted down the difficulty encountered during the placement of ABI electrode. Auditory perception and speech intelligibility was scored post operatively for 1 year. ResultsCerebellar flocculus was divided into 4 grades depending on the morphology of cerebellar flocculus. It was noted that Grade 3 & 4 flocculus (Group B) had difficult ABI electrode placement in comparison to Grade 1 & 2 flocculus (Group A). The subjective outcomes of Group A was better than Group B. However the p value was not statistically significant. ConclusionCerebellar flocculus can be graded depending on morphology and size. Flocculus of higher grades can make the placement of ABI electrodes difficult and adversely effects the postoperative subjective outcomes.

Safety of Monopolar Electrocautery in Patients With Cochlear Implants.

The outcomes of 2 patients with cochlear implants (CIs) who underwent adenotonsillectomy (AT) with inadvertent use of monopolar cautery are presented. The safety data regarding monopolar cautery use in CI recipients is also reviewed. This is a retrospective case series of 2 CI recipients that underwent AT with monopolar cautery and literature review of electrocautery safety in the setting of CI. Two patients with CIs underwent AT with use of monopolar cautery inadvertently by surgeons that do not routinely perform cochlear implants as part of his or her clinical practice. Patient 1 was a 9-year-old female who had AT for obstructive sleep apnea (OSA) after undergoing unilateral CI for profound congenital sensorineural hearing loss (SNHL) 8 years ago. Patient 2 was a 7-year-old female who underwent AT for OSA 4 months after undergoing unilateral CI for congenital SNHL. Both patients had no immediate signs of complications with their CI use postoperatively. Both patients demonstrated unchanged postoperative neural response telemetry and behavioral audiometric testing. Patient 1 continues to have no CI-related complications 3.5 years after the procedure. Patient 2 has been followed for at least 3 months by audiometric testing and 10 months by otolaryngologist with no CI-related complications. Although animal and cadaveric studies suggest that monopolar cautery may be safely used in patients with cochlear implants, there have been no in vivo human studies that have evaluated the risk to the patient or implant. This is a report of a small, unintended experience with 2 patients, both of whom exhibit no complications or changes to CI function thus far.

A novel nonsense GPSM2 mutation in a Yemeni family underlying Chudley-McCullough syndrome

Mutations in the G Protein Signaling Modulator 2 (GPSM2) cause the autosomal recessive disorder Chudley-McCullough syndrome (CMS), which is characterized by profound congenital sensorineural hearing loss with various abnormalities in the brain. This phenotypic combination is attributed to the role played by GPSM2 in the establishment of planar polarity and spindle orientation during asymmetric cell divisions. Here we present two brothers from a Yemeni family who were diagnosed clinically with CMS then tested for GPSM2 mutations using Sanger sequencing. Consequent to sequencing, in silico tools (such as CADD) were utilized to assess functional consequences. Molecular analysis revealed a previously unreported homozygous mutation in GPSM2 in both brothers (c.1055C > A) leading to a truncating protein change; (p.Ser352*). This mutation is predicted to abolish all four GoLoco domains in GPSM2 and this explains the bioinformatic prediction for this mutation to be functionally damaging. Full clinical and molecular accounts of the novel mutation are provided in this paper.

Social conversational skills development in early implanted children.

Social conversational skills are a salient aspect of early pragmatic development in young children. These skills include two different abilities, assertiveness and responsiveness. This study investigated the development of these abilities in early implanted children and their relationships with lexical development and some language-sensitive variables. Prospective, observational, nonrandomized study. Participants included 28 children with congenital profound sensorineural hearing loss. The mean age at device activation was 13.3 months (standard deviation [SD] ±4.2). The Social-Conversational Skills Rating Scale was used to evaluate assertiveness and responsiveness. The MacArthur-Bates Communicative Development Inventory (Words and Sentences form) was used to analyze the lexical development. The device experience was 12 months for each child, and the mean age at testing was 25.9 months (SD ±4.6). Assertiveness and responsiveness scores were within the normal range of normal-hearing age-matched peers. Age at cochlear implant activation exerted a significant impact, with the highest scores associated to the youngest patients. The residual correlations between assertiveness and responsiveness with the lexical development were positive and strongly significant (r = 0.69 and 0.73, respectively). Preoperative hearing threshold demonstrated an associated significant coefficient on the assertiveness score. Age at diagnosis and maternal education level were not correlated with the social conversational skills. Early-implanted children developed social conversational skills that are similar to normal-hearing peers matched for age 1 year after device activation. Social conversational skills and lexical development were strongly correlated, but the present study design cannot specify the direction of this relationship. Children with better preoperative residual hearing exhibited better assertive ability. 4 Laryngoscope, 126:2098-2105, 2016.

The role of transcription factors of neurosensory cells in non-syndromic sensorineural hearing loss with or without inner ear malformation

Conclusions: Previous studies have stated the roles and correlation of the four TFs (Sox2, Atoh1, Neurog1, and Neurod1) in the development of neurosensory cells. but whether they are inherited pathogenic factors to cause non-syndromic sensorineural hearing loss is unknown so far. This is the first time for screening the Sox2, Atoh1, Neurog1, and Neurod1 genes in children with NSHL. The c.133A > G in Neurod1 gene is a polymorphism, which is not associated with NSHL. Although these genes are the recognized TFs for modulating the development and transformation of NSCs, they may not be the inherited pathogenic factors to cause congenital severe or profound NSHL directly. Objective: To investigate the effect of the transcription factors (TFs) for the development of neurosensory cells (NSCs) and to explore the genetic etiology of congenital profound non-syndromic sensorineural hearing loss (NSHL). Methods: Children with NSHL, from multi-national and regional group, and control group were recruited to screen for the most common mutations for non-syndromic deafness among East Asian (mtDNA 12S rRNA: 1555A > G, 1494C > T; SLC26A4: IVS7-2 A > G, 2168 C > T). And mutational analysis of the coding regions in Sox2, Atoh1 and Neurog1, Neurod1 genes were performed. Results: Only the c.133A > G (p. Ala45Thr) in the Neurod1 gene was detected in this study. The allele frequencies of this variant were 88.00% and 84.88% in the inner ear malformation group and the normal inner ear group, respectively, while 90.85% of children in the control group carried c.133A > G. This variant existed in every group commonly and had no significant difference among them. No variant in the other two TFs was detected in this cohort.

Identification and Clinical Implications of Novel MYO15A Mutations in a Non-consanguineous Korean Family by Targeted Exome Sequencing.

Mutations of MYO15A are generally known to cause severe to profound hearing loss throughout all frequencies. Here, we found two novel MYO15A mutations, c.3871C>T (p.L1291F) and c.5835T>G (p.Y1945X) in an affected individual carrying congenital profound sensorineural hearing loss (SNHL) through targeted resequencing of 134 known deafness genes. The variant, p.L1291F and p.Y1945X, resided in the myosin motor and IQ2 domains, respectively. The p.L1291F variant was predicted to affect the structure of the actin-binding site from three-dimensional protein modeling, thereby interfering with the correct interaction between actin and myosin. From the literature analysis, mutations in the N-terminal domain were more frequently associated with residual hearing at low frequencies than mutations in the other regions of this gene. Therefore we suggest a hypothetical genotype-phenotype correlation whereby MYO15A mutations that affect domains other than the N-terminal domain, lead to profound SNHL throughout all frequencies and mutations that affect the N-terminal domain, result in residual hearing at low frequencies. This genotype-phenotype correlation suggests that preservation of residual hearing during auditory rehabilitation like cochlear implantation should be intended for those who carry mutations in the N-terminal domain and that individuals with mutations elsewhere in MYO15A require early cochlear implantation to timely initiate speech development.

Pediatric Cochlear Implantation-Why the Delay.

The aim of the study was to evaluate the factors that act as barriers and delay the process of cochlear implantation in children with congenital profound sensorineural hearing loss. This is a cross sectional observational study in which 154 children with profound sensorineural deafness attending ENT outdoor from Jan 2013 to June 2014 at Sri Aurobindo Institute of Medical College and PG Institute, Indore, were included in the study. Information was taken from the parents of the candidates regarding the reasons for the delay in reporting, the delay in intervention and a detailed history was also taken to evaluate the possible reason for the hearing loss with the help of open ended questions. The most common cause for the delay in reporting was lack of information about the availability of technique and procedure for cochlear implant. Financial constrain was the most common cause for the delay in getting the cochlear implant surgery.

High-resolution computerized tomography and Magnetic Resonance Imaging (MRI) in preoperative evaluation of cochlear implant patients

Context Preoperative cross-sectional imaging evaluation of cochlear implant patients is critically important in deciding whether the patient is suitable for implantation and in choosing the side of implantation. Aims The aim of this prospective study was to determine the incidence of structural cochlear anomalies in patients with congenital profound bilateral sensorineural hearing loss, who were being evaluated for the feasibility of cochlear implantation. Settings and design This was a prospective observational nonrandomized study. Patients and methods A total of 26 patients with congenital profound bilateral sensorineural hearing loss, who were being evaluated for feasibility of cochlear implantation were included in this study. These patients were evaluated with high-resolution computerized tomography of the temporal bone and MRI for incidence of structural cochlear anomalies. Results The incidence of structural cochlear anomalies, excluding cochlear nerve aplasia, in patients with congenital profound bilateral sensorineural hearing loss, who were being evaluated for the feasibility of cochlear implantation was 50%. Conclusion This study highlights the importance of preoperative radiological scanning in the assessment of patients undergoing cochlear implantation. It provides vital information on cochlear status and in ruling out noncochlear causes where cochlear implantation is not feasible or contraindicated.

P300 in individuals with sensorineural hearing loss

IntroductionBehavioral and electrophysiological auditory evaluations contribute to the understanding of the auditory system and of the process of intervention. ObjectiveTo study P300 in subjects with severe or profound sensorineural hearing loss. MethodsThis was a descriptive cross-sectional prospective study. It included 29 individuals of both genders with severe or profound sensorineural hearing loss without other type of disorders, aged 11 to 42 years; all were assessed by behavioral audiological evaluation and auditory evoked potentials. ResultsA recording of the P3 wave was obtained in 17 individuals, with a mean latency of 326.97ms and mean amplitude of 3.76V. There were significant differences in latency in relation to age and in amplitude according to degree of hearing loss. There was a statistically significant association of the P300 results with the degrees of hearing loss (p=0.04), with the predominant auditory communication channels (p<0.0001), and with time of hearing loss. ConclusionsP300 can be recorded in individuals with severe and profound congenital sensorineural hearing loss; it may contribute to the understanding of cortical development and is a good predictor of the early intervention outcome.

Identification of D179H, a novel missense GJB2 mutation in a Western Sicily family

The main purpose of this study was to describe a novel missense mutation (p.D179H) found in a Western Sicily family and to examine the genetic and audiologic profiles of all family members by performing a GJB2 and GJB6 mutations analysis and a complete audiologic assessment. The proband was a 3-month-old infant with a congenital profound sensorineural hearing loss; direct sequencing of the GJB2 revealed the presence of a c.35delG mutation in the heterozygous state and a heterozygous G>C transition at nucleotide 535 in trans; this novel mutation, called p.D179H, resulted in an aspartic acid to histidine change at codon 179. It was also evidenced in the heterozygous state in two members of this family, both with normal hearing. No GJB6 mutations were evidenced in all subjects studied. Considering the genotypic and phenotypic analysis of all family members, we suggest, differently from the p.D179N mutation previously reported, a recessive mode of inheritance. Functional studies on p.D179H have to be performed to confirm our hypothesis.

The polymorphisms of the MBL2 and MIF genes associated with Pediatric Cochlear Implant Patients

ObjectivesMannose-binding lectin and macrophage migration inhibitory factor gene polymorphisms are associated with several acute/chronic autoimmune or inflammatory diseases. The aim of this study was to investigate if there was any association between mannose-binding lectin 2 (MBL2) and macrophage migration inhibitory factor (MIF) gene polymorphisms and profound congenital sensorineural hearing loss in children who underwent cochlear implantation. MethodsA total of 62 patients with congenital hearing loss and 80 age- and sex-matched healthy controls were evaluated for codon 54 A/B polymorphisms in MBL2 and the-173 G/C polymorphism in MIF by using the polymerase chain reaction and restriction fragment length polymorphism method. ResultsThe frequency of the BB genotype of MBL2 and MIF −173 GC genotype were statistically significantly higher in the patient group than in the controls (p=0.0127, p=0.0408, respectively). ConclusionIn this study, we found that a subject who is homozygous for the variant allele B of codon 54 of the MBL2and heterozygous for variant allele C of −173 MIF has a risk factor for sensorineural hearing loss.

BILINGUALISM IN CHILDREN HAVING CONGENITAL BILATERAL PROFOUND SENSORI NEURAL HEARING LOSS – CASE REVIEW

The age old understanding that an individual with a hearing loss is incapable of acquiring verbal communication skills was readily accepted in the past, which led to the inadvertent but unfortunate coining of phrases “deaf and dumb” or “deaf and mute, " and the development of non-verbal or manual communication methodolgies of Sign language. Further, this caused the segregation and isolation of otherwise physically and intellectually competent individuals from mainstream society, unjustifiably denying them opportunities of education and vocation. Studies have proved that in the absence of any organic or inorganic complication, a child with a hearing loss may not only score a high Intelligence Quotient but can also acquire more than one language fluently. Early Intervention with appropriate amplification of residual hearing is underscored as the fundamental prerequisite for children with bilateral congenital profound sensorineural hearing loss, for subsequent acquisition of good listening and normal speech-language skills and plausible bilingualism; that further equips them with scholastic achievements comparable to their hearing peers. The past half century has witnessed stupendous technological enhancements in amplification devices manufactured for children having hearing loss, complemented by steady success in fostering their Inclusive Education. This paper highlights the urgent need in Pakistan to address this issue as well as the importance of early detection, diagnosis, and (re)habilitation along with parent training initiated within the first year of life. An otherwise anticipated disabling condition may be overcome completely if neonatal screening, which is not only inexpensive but also easy to perform; is made mandatory at all hospitals and maternity homes, as practiced in the developed world. This shall ease the challenges faced by the families of children having hearing loss; and enable the professionals working with them to successfully alleviate their communicative, social, educational and vocational difficulties, and ensure that they become successfully contributing members of our verbal society.

Profound deafness and the acquisition of spoken language in children.

Profound congenital sensorineural hearing loss (SNHL) is not so infrequent, affecting 1 to 2 of every 1000 newborns in western countries. Nevertheless, universal hearing screening programs have not been widely applied, although such programs are already established for metabolic diseases. The acquisition of spoken language is a time-dependent process, and some form linguistic input should be present before the first 6 mo of life for a child to become linguistically competent. Therefore, profoundly deaf children should be detected early, and referred timely for the process of auditory rehabilitation to be initiated. Hearing assessment methods should reflect the behavioural audiogram in an accurate manner. Additional disabilities also need to be taken into account. Profound congenital SNHL is managed by a multidisciplinary team. Affected infants should be bilaterally fitted with hearing aids, no later than 3 mo after birth. They should be monitored until the first year of age. If they are not progressing linguistically, cochlear implantation can be considered after thorough preoperative assessment. Prelingually deaf children develop significant speech perception and production abilities, and speech intelligibility over time, following cochlear implantation. Age at intervention and oral communication, are the most important determinants of outcomes. Realistic parental expectations are also essential. Cochlear implant programs deserve the strong support of community members, professional bodies, and political authorities in order to be successful, and maximize the future earnings of pediatric cochlear implantation for human societies.

Cochlear implantation in the congenitally malformed ear

Approximately 20%-35% of patients with profound congenital sensorineural hearing loss have radiographic evidence of anatomic inner ear abnormalities. 1 Jackler R.K. Luxford W.M. House W.F. Congenital malformations of the inner ear: A classification based on embryogenesis. Laryngoscope. 1987; 97: 2-14 Crossref PubMed Scopus (622) Google Scholar , 2 Parry D.A. Booth T. Roland P.S. Advantages of magnetic resonance imaging over computed tomography in preoperative evaluation of pediatric cochlear implant candidates. Otol Neurotol. 2005; 26: 976-982 Crossref PubMed Scopus (114) Google Scholar , 3 McClay J.E. Tandy R. Grundfast K. et al. Major and minor temporal bone abnormalities in children with and without congenital sensorineural hearing loss. Arch Otolaryngol Head Neck Surg. 2002; 128: 664-671 Crossref PubMed Scopus (92) Google Scholar , 4 Papsin B.C. Cochlear implantation in children with anomalous cochleovestibular anatomy. Laryngoscope. 2005; 115: 1-26 Crossref PubMed Scopus (262) Google Scholar In the past, congenital malformations of the inner ear were considered by some to be a contraindication to cochlear implantation due to surgical concerns over electrode placement as well as expected poor audiologic performance. 5 Phelps P.D. Cochlear implants for congenital deformities. Jour Laryn Oto. 1992; 106: 967-970 Crossref Scopus (38) Google Scholar With the advent of improved imaging modalities as well as refined surgical techniques, implantation of the malformed inner ear is now performed frequently. In addition, recent studies continue to demonstrate a significant hearing benefit from cochlear implants in patients with inner ear dysplasia. 6 Buchman C.A. Copeland B.J. Yu K.K. et al. Cochlear implantation in children with congenital inner ear malformations. Laryngoscope. 2004; 114: 309-316 Crossref PubMed Scopus (117) Google Scholar , 7 Hoffman R.A. Downey L.L. Waltzman S.B. et al. Cochlear implantation in children with cochlear malformations. Am J Otol. 1997; 18: 184-187 PubMed Google Scholar These hearing results, however, tend to correlate with the severity of the inner ear malformation.

Feasibility analysis and surgical highlight of cochlear implantation in infants under 12 months of age

To explore feasibility and surgical highlight of cochlear implantation in infants under 12 months of age. A retrospective review was performed in 14 infants under 12 months of age and 63 cases from 13 to 24 months of age with bilateral profound sensorineural hearing loss, who underwent unilateral cochlear implantation surgery. The operative parameters, including operation duration, amount of intraoperative bleeding, length of hospital stay, surgical complications and auditory outcomes, including warble tone average aided in free field, category of auditory performance (CAP), language behavior development quotient, babbling onset or spurt were recorded. There was no significant difference between infants younger than 12 months and older in operation duration, amount of intraoperative bleeding, except for the length of hospital stay. Otherwise, less complication occurred in younger group (7.1% and 11.1%, respectively, χ(2) = 0.19, P > 0.05). The surgical highlights and experience, strictly restricted operation duration, intimate cooperation among the treatment team members and reduction of intraoperative bleeding are key points to ensure safety and success of the operation. The warble tone average aided in free field and language behavior developmental quotient of younger infants were both improved during follow-up and showed no significant difference compared with older group (t = 4.6 and 3.8, P > 0.05). 80% of infants who finished 24 months follow-up had a CAP score of 6 or 7. The babbling onset in younger group occurred at (14.1 ± 0.9) months of life, which was better than that in older group [(22.6 ± 3.0) months of life]. It is feasible to put cochlear implantation in infants under 12 months of age. And the earlier cochlear implantation could shorten auditory deprivation for children with bilateral congenital profound sensorineural hearing loss. Considering the high requirement of surgical highlights and experience, the suggest was that only experienced otologists challenge this domain cautiously.

Speech Perception in Congenitally Deaf Children Receiving Cochlear Implants in the First Year of Life

To investigate whether children implanted in the first year of life show higher levels of speech perception than later-implanted children, when compared at the same ages and to investigate the time course of sensitive periods for developing speech perception skills. More specifically, to determine whether faster gains in speech perception are made by children implanted before 1 year old relative to those implanted at 2 or 3 years. Retrospective cohort study. Tertiary academic referral center. 117 children with congenital profound bilateral sensorineural hearing loss, with no additional identified disabilities. Cochlear implantation in the first, second, or third year of life. Development curves showing Lexical Neighborhood Test (LNT) word identification scores as a function of age. Children implanted within the first year of life have a mean advantage of 8.2% LNT-easy word scores over those implanted in the second year (p < 0.001) and a 16.8% advantage in LNT-easy word scores over those implanted in the third year of life (p < 0.001). These advantages remained statistically significant after accounting for sex, residual hearing, and bilateral cochlear implant use. When speech perception scores were expressed as a function of "hearing age" rather than chronological age, however, there were no significant differences among the 3 groups. There is a clear speech perception advantage for earlier-implanted children over later-implanted children when compared at the same age but not when compared at the same time after implantation. Thus, the sensitive period for developing word identification seems to extend at least until age 3 years.

Vestibular myogenic potentials of athletes for the Deaf Olympic Games with congenital profound hearing loss

Conclusions: Our study revealed that VEMPs in responses to clicks and 500 Hz STB were abnormal in 25% of athletes with congenital profound sensorineural hearing loss for the Deaf Olympic Games. These results confirm that a part of deaf athletes with congenital vestibular failure is well compensated for higher level sport activities. Objectives: The aim of this study was to investigate the appearance rate of VEMP, vestibular failure and its compensation in Japanese deaf athletes by the VEMP test, caloric test and balance test. Methods: Sixteen subjects among the Deaf Olympic Games athletes of Japan volunteered to participate in this study. All the subjects have congenital profound sensorineural hearing loss. Results: In the VEMP test, 24 ears (75%) showed normal click-evoked responses, 5 ears (16%) showed decreased click-evoked responses, 3 ears (9%) showed no click-evoked responses, 28 ears (87.5%) showed normal 500 Hz short tone burst (STB)-evoked responses and 4 ears (12.5%) showed decreased responses. In the ice-water caloric test, 11 subjects (69%) showed normal responses bilaterally, 3 subjects showed bilateral responses with asymmetrical responses and 2 subjects (12%) showed no response bilaterally. All the subjects showed normal balance test results.

An Exploratory Look at Pediatric Cochlear Implantation: Is Earliest Always Best?

Since the advent of cochlear implants, age at implantation has declined as investigators report greater benefit the younger a child is implanted. Infants younger than 12 mos currently are excluded from Food and Drug Administration clinical trials, but have been implanted with Food and Drug Administration-approved devices. With a chance that an infant without profound hearing loss could be implanted because of the limitations of the diagnostic measures used with this population and the potential for additional anesthetic risks to infants younger than 1-yr-old, it is prudent to evaluate benefit in the youngest cochlear implant recipients. The goals of this research were to investigate whether significant gains are made by children implanted before 1-yr-old relative to those implanted at later ages, while controlling for potential covariates, and whether there is behavioral evidence for sensitive periods in spoken language development. It was expected that children implanted before age 1 yr would have more advanced spoken language skills than children implanted at later ages; there would be a negative relationship between age at implantation and rate of spoken language development, allowing for an examination of the effects of sensitive periods in spoken language development; and these trends would remain despite accounting for participant characteristics and experiences that might influence spoken language outcomes. Ninety-six children with congenital profound sensorineural hearing loss bilaterally and no additional identified disabilities who were implanted before the age of 4 yrs were stratified into four groups based on age at implantation. Children's spoken language development was followed for at least 2 yrs after device activation. Spoken language scores and rate of development were evaluated along with four covariates (unaided pure-tone average, communication mode, gender, and estimated family income) as a function of age at implantation. In general, the developmental trajectories of children implanted earlier were significantly better than those of children implanted later. However, the advantage of implanting children before 1-yr old versus waiting until the child was between 1 and 2 yrs was small and only was evident in receptive language development, not expressive language or word recognition development. Age at implantation did not significantly influence the rate of the word recognition development, but did influence the rate of both receptive and expressive language acquisition: children implanted earlier in life had faster rates of spoken language acquisition than children implanted later in life. Although in general earlier cochlear implantation led to better outcomes, there were few differences in outcome between the small sample of six children implanted before 12 mos of age and those implanted at 13 to 24 mos. Significant performance differences remained among the other age groups despite accounting for potential confounds. Further, oral language development progressed faster in children implanted earlier rather than later in of life (up to age 4 yrs), whereas the rate of open-set speech recognition development was similar. Together, the results suggest that there is a sensitive period for spoken language during the first 4 yrs of life, but not necessarily for word recognition development during the same period.

Quantitative Analysis of Electrically Evoked Auditory Brainstem Responses in Implanted Children With Auditory Neuropathy/Dyssynchrony

Cochlear implantation is a common treatment approach for children with auditory neuropathy/dyssynchrony (AN/AD) who do not benefit from hearing aids. The auditory brainstem response (ABR) is a measure of neural synchrony along the auditory pathway up through the brainstem. By definition, acoustically evoked ABR is absent in AN/AD, however, ABR can be elicited by electrical stimulation through the cochlear implant (electrically evoked ABR [EABR]). Reports of EABR with AN/AD to date have been primarily descriptive in nature. The objective of this study was to quantify EABR wave V measures in implanted children with and without AN/AD. Retrospective analysis of EABR waveforms from March 2000 through February 2005. Comprehensive Cochlear Implant Program/Tertiary Referral Center. Pediatric cochlear implant users of two etiologic groups: congenital AN/AD (n = 5) and other congenital profound sensorineural hearing loss (n = 27). Diagnostic. Intraoperative EABR wave V threshold, suprathreshold amplitude, and latency measures were compared between groups. The EABR threshold and suprathreshold amplitude measures across the population were variable regardless of etiology. With some exceptions, a trend was observed for the AN/AD group that included average or below-average thresholds and below-average suprathreshold response amplitudes. Cochlear implantation can provide synchronous neural responses to auditory stimulation in AN/AD, as previously known. The quantification of EABR measures in this study indicates that subjects with AN/AD have sufficient neural sensitivity to electrical stimulation, however, they may experience less robust neural responses at suprathreshold levels. Given the heterogeneity of potential causes of AN/AD, however, caution needs to be applied when grouping this population for analyses.

Autosomal recessive nonsyndromic deafness locus DFNB63 at chromosome 11q13.2–q13.3

A genome wide linkage analysis of nonsyndromic deafness segregating in a consanguineous Pakistani family (PKDF537) was used to identify DFNB63, a new locus for congenital profound sensorineural hearing loss. A maximum two-point lod score of 6.98 at theta = 0 was obtained for marker D11S1337 (68.55 cM). Genotyping of 550 families revealed three additional families (PKDF295, PKDF702 and PKDF817) segregating hearing loss linked to chromosome 11q13.2-q13.3. Meiotic recombination events in these four families define a critical interval of 4.81 cM bounded by markers D11S4113 (68.01 cM) and D11S4162 (72.82 cM), and SHANK2, FGF-3, TPCN2 and CTTN are among the candidate genes in this interval. Positional identification of this deafness gene should reveal a protein necessary for normal development and/or function of the auditory system.