Cause Of Deafness Research Articles

Molecular Epidemiology and Functional Assessment of Novel Allelic Variants of SLC26A4 in Non-Syndromic Hearing Loss Patients with Enlarged Vestibular Aqueduct in China

BackgroundMutations in SLC26A4, which encodes pendrin, are a common cause of deafness. SLC26A4 mutations are responsible for Pendred syndrome and non-syndromic enlarged vestibular aqueduct (EVA). The mutation spectrum of SLC26A4 varies widely among ethnic groups. To investigate the incidence of EVA in Chinese population and to provide appropriate genetic testing and counseling to patients with SLC26A4 variants, we conducted a large-scale molecular epidemiological survey of SLC26A4.MethodsA total of 2352 unrelated non-syndromic hearing loss patients from 27 different regions of China were included. Hot spot regions of SLC26A4, exons 8, 10 and 19 were sequenced. For patients with one allelic variant in the hot spot regions, the other exons were sequenced one by one until two mutant alleles had been identified. Patients with SLC26A4 variants were then examined by temporal bone computed tomography scan for radiological diagnosis of EVA. Ten SLC26A4 variants were cloned for functional study. Confocal microscopy and radioisotope techniques were used to examine the membrane expression of pendrin and transporter function.ResultsOf the 86 types of variants found, 47 have never been reported. The ratio of EVA in the Chinese deaf population was at least 11%, and that in patients of Han ethnicity reached at least 13%. The mutational spectrum and mutation detection rate of SLC26A4 are distinct among both ethnicities and regions of Mainland China. Most of the variants caused retention of pendrin in the intracellular region. All the mutant pendrins showed significantly reduced transport capability.ConclusionAn overall description of the molecular epidemiological findings of SLC26A4 in China is provided. The functional assessment procedure can be applied to identification of pathogenicity of variants. These findings are valuable for genetic diagnosis, genetic counseling, prenatal testing and pre-implantation diagnosis in EVA families.

Influenza A (H1N1): a rare cause of deafness in two children

We report deafness occurring as an extremely rare complication of influenza A caused by the H1N1 virus ('swine flu'), in two children. Case reports and review of the literature concerning influenza A (H1N1) and acquired viral infection causing deafness. Two children with normal hearing developed bilateral deafness following influenza A (H1N1). The diagnosis was confirmed using polymerase chain reaction. Both patients were treated with oseltamivir. Following a review of the literature, these two patients appear to be the first reported cases of bilateral deafness following influenza A (H1N1).

Prediction of cochlear implant performance by genetic mutation: The spiral ganglion hypothesis

BackgroundUp to 7% of patients with severe-to-profound deafness do not benefit from cochlear implantation. Given the high surgical implantation and clinical management cost of cochlear implantation (>$1 million lifetime cost), prospective identification of the worst performers would reduce unnecessary procedures and healthcare costs. Because cochlear implants bypass the membranous labyrinth but rely on the spiral ganglion for functionality, we hypothesize that cochlear implant (CI) performance is dictated in part by the anatomic location of the cochlear pathology that underlies the hearing loss. As a corollary, we hypothesize that because genetic testing can identify sites of cochlear pathology, it may be useful in predicting CI performance. Methods29 adult CI recipients with idiopathic adult-onset severe-to-profound hearing loss were studied. DNA samples were subjected to solution-based sequence capture and massively parallel sequencing using the OtoSCOPE® platform. The cohort was divided into three CI performance groups (good, intermediate, poor) and genetic causes of deafness were correlated with audiometric data to determine whether there was a gene-specific impact on CI performance. ResultsThe genetic cause of deafness was determined in 3/29 (10%) individuals. The two poor performers segregated mutations in TMPRSS3, a gene expressed in the spiral ganglion, while the good performer segregated mutations in LOXHD1, a gene expressed in the membranous labyrinth. Comprehensive literature review identified other good performers with mutations in membranous labyrinth-expressed genes; poor performance was associated with spiral ganglion-expressed genes. ConclusionsOur data support the underlying hypothesis that mutations in genes preferentially expressed in the spiral ganglion portend poor CI performance while mutations in genes expressed in the membranous labyrinth portend good CI performance. Although the low mutation rate in known deafness genes in this cohort likely relates to the ascertainment characteristics (postlingual hearing loss in adult CI recipients), these data suggest that genetic testing should be implemented as part of the CI evaluation to test this association prospectively.

Hearing impairments among Saudi preschool children

BackgroundHearing loss among school-entrant children in the developing world has been widely reported as a significant health problem. Failure to detect hearing loss, either congenital or acquired, in children may result in lifelong deficits in speech and language acquisition. The aims of this study were: (1) to estimate the prevalence of hearing loss and (2) to identify its different types. MethodsThis is a cross-sectional study that included all children (n=2574) aged 4–8 years who attended the obligatory health examination for kindergarten (=370) and primary school (n=2204) entry at the school health center of King Abdulaziz Medical City, Riyadh, Saudi Arabia, from March 2009 to December 2010. Pure-tone air conduction audiometry was conducted for each child in a sound-treated room followed by a diagnostic test. Tympanometry was performed as a complement to the overall objectives of a hearing screening program. ResultsA total of 45 children were diagnosed with hearing impairment (84.4% conductive and 15.6% sensori-neural), with an overall prevalence of 1.75% (95% C.I.: 1.25, 2.25). The majority of cases were females (71.1%), of school age (80.0%), with conductive deafness (84.4%). More than one-half of cases had bilateral deafness (55.6%) of mild degree (57.8%). As for conductive deafness, otitis media with effusion ranked first as a cause of deafness (34.9%), followed by wax and chronic otitis media (23.3% each), while traumatic perforated drum came last (2.3%). Sensorineural deafness constituted 16.2% of all cases. ConclusionConductive hearing loss is the primary type of hearing loss among children and is easy to correct. The urgent development of audiological services in other school health centers in the country, particularly those with good referral systems to Ministry of Health hospitals, is needed. Evidence-based guidelines to identify, monitor, and manage otitis media with effusion (OME) in children in the primary healthcare setting and a strategy to prevent hearing loss are recommended.

Cognitive skills in children with Usher syndrome type 1 and cochlear implants

IntroductionUsher syndrome is a genetic condition causing deaf-blindness and is one of the most common causes of syndromic deafness. Individuals with USH1 in Sweden born during the last 15 years have typically received cochlear implants (CI) as treatment for their congenital, profound hearing loss. Recent research in genetics indicates that the cause of deafness in individuals with Usher type 1 (USH1) could be beneficial for the outcome with cochlear implants (CI). This population has not previously been the focus of cognitive research. ObjectiveThe present study aims to examine the phonological and lexical skills and working memory capacity (WMC) in children with USH1 and CI and to compare their performance with children with NH, children with hearing-impairment using hearing-aids and to children with non-USH1 deafness using CI. The participants were 7 children aged 7–16 years with USH1 and CI. MethodsThe participants performed 10 sets of tasks measuring phonological and lexical skills and working memory capacity. ConclusionsThe results indicate that children with USH1 and CI as a group in general have a similar level of performance on the cognitive tasks as children with hearing impairment and hearing aids. The group with USH1 and CI has a different performance profile on the tests of working memory, phonological skill and lexical skill than children with non-USH1 deafness using CI, on tasks of phonological working memory and phonological skill.

Etiologic Diagnosis of Nonsyndromic Genetic Hearing Loss in Adult vs Pediatric Populations

Determine the diagnostic yield of a shared genetic testing algorithm in adult and pediatric populations with sensorineural hearing loss (SNHL) and recommend effective testing strategies to evaluate for genetic causes of deafness in patients presenting with idiopathic sensorineural hearing loss. Hospital-based cohort study. University of Miami outpatient otology clinics between 2001 and 2010. Two hundred twenty-one adult and 163 pediatric patients with nonsyndromic sensorineural hearing loss. Peripheral blood samples were screened for mutations in GJB2 and GJB6 and mitochondrial DNA mutations 1555A>G, 7444G>A, and 3243A>G. Audiometric data and family history were also collected. GJB2/GJB6-related deafness was diagnosed in 23 of 163 pediatric patients (14%) compared with only 3 of 221 adults (1%). All adults had a family history of hearing loss, and 2 patients noted deafness onset at birth. Nineteen GJB2 mutations were identified with 35delG the most common mutation. The 35delG homozygous state was the most common pathogenic genotype (54%). Mitochondrial DNA (mtDNA) mutations were found in 6 adult probands (3%). No mtDNA mutations were found in pediatric patients. Testing for common GJB2/GJB6 mutations in pediatric patients has considerable value in establishing an etiologic diagnosis for SNHL. Similar testing in adults is of very low yield except perhaps in cases of early-onset SNHL or strong family history. Mitochondrial DNA testing should be considered in adults with idiopathic SNHL.

Infección congénita por citomegalovirus: presentación de tres casos y revisión de la literatura

La infección perinatal más frecuente es causada por citomegalovirus (CMV), en el feto y el recién nacido esta infección es la principal causa de sordera y compromiso en el desarrollo psicomotor; el tamizaje, diagnóstico y manejo no se han protocolizado en el control prenatal. El pronóstico de estos pacientes dependerá de un manejo adecuado. Se presentan tres casos con el objetivo de revisar el diagnóstico prenatal y el manejo en el neonato.Materiales y métodos: se muestran tres casos de infección congénita por citomegalovirus diagnosticados en el Hospital Universitario Hernando Moncaleano de Neiva-Huila, centro de referencia de la región suroccidental de Colombia. Se realizó una búsqueda electrónica en las bases de datos de PudMed, Embase, Medline, Lilacs, Cochrane.Resultados: se encontraron 31 artículos, dos guías basadas en evidencia, seis revisiones sistemáticas, dos consensos de la Asociación Española de Pediatría, cuatro estudios de casos y controles, cuatro estudios de cohortes, doce revisiones narrativas, un estudio analítico de decisiones y de costos.Conclusión: el tamizaje rutinario para CMV en el control prenatal no está recomendado. Se debe hacer tamizaje en mujeres gestantes de alto riesgo. El método de tamizaje son la inmunoglobulina IgM específica y el test de avidez por IgG, si esta es baja confirma infección reciente. La prueba confirmatoria es la PCR para CMV. En recién nacidos la prueba de tamizaje es la PCR y el patrón de oro es el cultivo viral. En mujeres con infección gestacional se debe aplicar inmunoglobulina específica para protección fetal.

Spectrum and frequency of mitochondrial 12S rRNA variants in the Chinese subjects with nonsynrdomic hearing loss in Zhejiang Prov-ince

Mitochondrial DNA (mtDNA) mutations are one of the important causes of deafness. In particular, the 12S rRNA gene is the hot spots for mutations associated with both aminoglycoside ototoxicity and nonsyndromic deafness. In this report, a total of 318 Chinese pediatric hearing-impaired subjects were recruited from otology clinics in the Zhejiang Province, China. These subjects underwent clinical, genetic evaluation and molecular analysis of 12S rRNA gene. Mutational analysis identified 34 variants in the 12S rRNA gene in this cohort. The incidences of the known deafness-associated 1555A>G, 1494C>T and 1095T>C mutations were 9.1%, 0.6% and 1.25% in this cohort, respectively. Other mtDNA variants were evaluated by structural and phylogenetic analysis. Of these, the 839A>G and 1452T>C variants could confer increased sensitivity to aminoglycosides or nonsyndromic deafness as they were not present in 449 Chinese controls and localized at highly conserved nucleotides of the 12S rRNA. However, other variants appeared to be polymorphisms. These data further support the idea that mitochondrial 12S rRNA is one of major targets for aminoglycoside ototoxicity. These data have been providing valuable information to predict which individuals are at risk for ototoxicity, to improve the safety of aminoglycoside antibiotic therapy, and eventually to decrease the incidence of deafness.

The novel c.247_249delTTC (p.F83del) GJB2 mutation in a family with prelingual sensorineural deafness

Non-syndromic hearing loss is one of the most common hereditary determined diseases in human, and the disease is a genetically heterogeneous disorder. Mutations in the GJB2 gene, encoding connexin 26 (Cx26), are a major cause of non-syndromic recessive hearing impairment in many countries and are largely dependent on ethnic groups. Due to the high frequency of the c.35delG GJB2 mutation in the Greek population, we have previously suggested that Greek patients with sensorineural, non-syndromic deafness should be tested for the c.35delG mutation and the coding region of the GJB2 gene should be sequenced in c.35delG heterozygotes. Here we present on the clinical and molecular genetic evaluation of a family suffering from prelingual, sensorineural, non-syndromic deafness. A novel c.247_249delTTC (p.F83del) GJB2 mutation was detected in compound heterozygosity with the c.35delG GJB2 mutation in the proband and was later confirmed in the father, while the mother was homozygous for the c.35delG GJB2 mutation. We conclude that compound heterozygosity of the novel c.247_249delTTC (p.F83del) and the c.35delG mutations in the GJB2 gene was the cause of deafness in the proband and his father.

Cochlear Blood Flow and Speech Perception Ability in Cochlear Implant Users

The effect of cochlear blood flow (CBF) on speech perception ability in cochlear implant (CI) users has not been reported. We investigated various factors influencing speech perception including CBF in CI users. Eighty-two patients who received CI surgery at an academic hospital. CBF was measured during CI surgery using laser Doppler flowmetry. The speech perception level was measured after a sufficient interval after CI surgery. Multivariate analysis was used to evaluate the influences of age, duration of deafness, sex, cause of deafness, and CBF on the speech perception level. CBF decreased significantly with age but was not related to the speech perception level. In patients with congenital hearing loss, the speech perception level was significantly worse in children who received a CI at 3 years of age than in those who received a CI at 2 years of age or younger. Duration of deafness before CI surgery had deteriorative effects on the speech perception level. CBF may be associated with progression of hearing loss. However, measuring CBF during CI surgery is not useful for predicting postoperative speech perception.

Genetic Screening ofGJB2andSLC26A4in Korean Cochlear Implantees: Experience of Soree Ear Clinic

ObjectivesGenetic hearing loss is highly heterogeneous and more than 100 genes are predicted to cause this disorder in humans. In spite of this large genetic heterogeneity, mutations in SLC26A4 and GJB2 genes are primarily responsible for the major etiologies of genetic hearing loss among Koreans. The purpose of this study is to investigate the genetic cause of deafness in Korean cochlear implantees by performing a genetic screening of the SLC26A4 and GJB2 genes.MethodsThe study cohort included 421 unrelated Korean patients with sensorineural hearing loss (SNHL) and who had received cochlear implants (CI) at Soree Ear Clinic from July 2002 to December 2010. Among 421 CI patients, we studied 230 cases who had received the genetic screening for SLC26A4 or GJB2 genes. Written informed consent was obtained from all participants. All patients had severe to profound, bilateral hearing loss. For 56 patients who showed enlarged vestibular aqueduct on their computed tomography (CT) scan, we analyzed SLC26A4. For 174 CT negative patients, GJB2 gene was sequenced.ResultsFor the 56 SLC26A4 patients, 32 (57.1%) had two pathogenic recessive mutations in SLC26A4. A single recessive SLC26A4 mutation was identified in 14 patients (25%). H723R and IVS7-2A>G were the most commonly found mutations, accounting for 60.3% (47/78) and 30.8% (24/78) of the mutated alleles, respectively. For the 174 GJB2 patients, 20 patients (11.5%) had two pathogenic recessive mutations in GJB2. 235delC was the most common mutation, accounting for 43.0% (31/72) of mutant alleles.ConclusionThe two major genes, SLC26A4 and GJB2, contribute major causes of deafness in CI patients. Continuous studies are needed to identify new genes that can cause hearing loss to Korean CI patients.

Two Portuguese Cochlear Implanted Dizygotic Twins: A Case Report

Individual's hearing performance after cochlear implant (CI) is variable and depends on different factors such as etiology of deafness, age at implantation, and social/family hearing environment. Here we report the case of dizygotic twins, boy and girl, presenting with neurosensorial profound deafness prior CI (age of implantation = 3.5 years old). Both parents have severe/profound deafness, since childhood, and use sign language as primary mode of communication. Clinical and genetic characterization was performed, as well as the assessment of the auditory and oral (re)habilitation after CI, applying a battery of audiological, speech, and language tests. The twin girl and the father were homozygous for the c.35delG mutation in the GJB2 gene, while the twin boy and the mother were compound heterozygotes, both monoallelic for c.35delG and for the deletion del(GJB6-D13S1830) in the GJB6 gene. The remaining hearing impaired relatives were c.35delG homozygotes. The genetic cause of deafness was thus identified in this family. Some noteworthy differences were observed regarding twins' auditory and oral performance after CI. Subsequent follow-up of these children allowed us to conclude that those differences were most likely due to the different environment in which the twins have been living than to their different GJB2/GJB6 genotypes.

Inbreeding as a cause for deafness: Dadhkai study

BACKGROUND:We report on the higher prevalence of deaf-mutes from a village in Jammu and Kashmir State of India.MATERIALS AND METHODS:A cross-sectional study among 79 deaf mutes using pedigree analysis, audiometry, imaging and molecular analysis.RESULTS:A high rate of hereditary deafness with 79 individuals diagnosed to be suffering from non-syndrome deafness in a total population of 2452 individuals residing in the village.INTERPRETATION:Flourishing of intermarriages led to a population with high prevalence of deafness

The study of gene GJB2/DFNB1 causing deafness in humans by linkage analysis from district Peshawar

Families with at least 2 or more individuals having hereditary hearing loss were enrolled from different areas of Khyber Pakhtoonkhwa, mainly from district Peshawar. Detailed history was taken from each family to minimize the presence of other abnormalities and environmental causes for deafness. Families were questioned about skin pigmentation, hair pigmentation, and problems relating to balance, vision, night blindness, thyroid, kidneys, heart, and infectious diseases like meningitis, antibiotic usage, injury, and typhoid. The pedigree structures were based upon interviews with multiple family members, and pedigrees of the enrolled families were drawn using Cyrillic program (version 2.1). All families showed recessive mode of inheritance. I studied 8 families of these 10. For linkage analyses, studies for DFNB1 locus, 3 STR markers (D13S175, D13S292, and D13S787) were genotyped using polyacrylamide gel electrophoresis (PAGE) and haplotypes were constructed to determined, linkage with DFNB1 locus. From a total of 8 families, a single family-10 showed linkage to DFNB1 locus.

Prevalence of mutations located at the dfnb1 locus in a population of cochlear implanted children in eastern Romania

Objective Hearing loss is one of the major public health problems, with a genetic etiology in more than 60% of cases. Connexin 26 and connexin 30 mutations are the most prevalent causes of deafness. The aim of this study is to characterize and to establish the prevalence of the GJB2 and GJB6 gene mutations in a population of cochlear implanted recipients from Eastern Romania, this being the first report of this type in our country. Methods We present a retrospective study that enrolled 45 Caucasian cochlear implanted patients with non-syndromic sensorineural severe to profound, congenital or progressive with early-onset idiopathic hearing loss. We performed sequential analysis of exon 1 and the coding exon 2 of the GJB2 gene including also the splice sites and analysis of the deletions del(GJB6-D13S1830), del(GJB6-D13S1854) and del(chr13:19,837,343–19,968,698). Results The genetic analysis of the GJB2 gene identified connexin 26 mutations in 22 patients out of 45 (12 homozygous for c.35delG, 6 compound heterozygous and 4 with mutations only on one allele). We found 6 different mutations, the most prevalent being c.35delG – found on 32 alleles, followed by p.W24* – found on 2 alleles. We did not identify the deletions del(GJB6-D13S1830), del(GJB6-D13S1854) and del(chr13:19,837,343–19,968,698). Conclusions Although the most prevalent mutation was c.35delG (80% from all types of mutations), unexpectedly we identified 5 more different mutations. The presence of 6 different mutations on the GJB2 gene has implications in hearing screening programs development in our region and in genetic counseling.

Etiologic Diagnosis of Nonsyndromic Genetic Hearing Loss in Adult vs Pediatric Populations

Objective: 1) Determine the diagnostic yield of a shared genetic screening algorithm in adult and pediatric populations with sensorineural hearing loss (SNHL). 2) Recommend effective testing strategies to evaluate for genetic causes of deafness in patients presenting with idiopathic sensorineural hearing loss. Method: A total of 221 adult and 163 pediatric patients with non-syndromic sensorineural hearing impairment were recruited from otology clinics between 2001 and 2011. Peripheral blood samples were screened for mutations in GJB2 and GJB6 and mitochondrial DNA mutations 1555A>G, 7444G>A, and 3243A>G. Audiometric data and family history were also collected. Results: GJB2/GJB6 related deafness was diagnosed in 23 out of 163 pediatric patients (14%) compared with only 3 out of 221 adults (1%). All 3 adults had a family history of hearing loss, and 2 patients noted deafness onset at birth. Nineteen GJB2 mutations were identified with 35delG, the most common mutation. The 35delG homozygous state was the most common pathogenic genotype (54%). Mitochondrial DNA (mtDNA) mutations were found in 6 adult probands (3%). No mtDNA mutations were found in pediatric patients. Conclusion: Testing for common GJB2/GJB6 mutations in pediatric patients has considerable value in establishing an etiologic diagnosis for SNHL. Similar testing in adults is of very low yield except perhaps in cases of early onset HL or strong family history. Mitochondrial DNA testing should be considered in adults with idiopathic SNHL.

Executive functioning and the impact of a hearing loss: Performance-based measures and the Behavior Rating Inventory of Executive Function (BRIEF)

The impact of deafness on a child's rated executive functioning behaviors and performance capabilities on neurological, cognitive, and achievement domains were examined in a sample of 22 deaf students (ages 5 to 18). The parent and teacher ratings on the Behavior Rating Inventory of Executive Function (BRIEF) showed significant positive correlations (p < .01) on six of the eight clinical scales. There were significant correlations between the BRIEF reports and the students' scores on the Wisconsin Card Sorting Test, the (Children's) Color Trails Test, and the Woodcock-Johnson: Writing Fluency subtest. The Wisconsin Card Sorting Test: Total Errors scale and the Writing Fluency subtest accounted for 70% variance of the parent BRIEF Global Executive Composite and 65% of the variance for the teacher report on this same composite scale. Students with genetic deafness were rated with significantly less challenges with executive functioning (p < .05) on BRIEF scales and performed significantly better on select student measures than students with other causes of deafness.

B014 Complications in 300 consecutive cases of cochlear implantations at sir ganga ram hospital, New Delhi

Cochlear implantation has become an effective treatment for many profoundly deaf patients. As with any surgical procedure, a proportion of patients suffer postoperative complications. The aim of this study was to analyze long-term postoperative complications in patients with cochlear implants with a view to improve clinical interventions and propose a consensus for reporting complications.A total of 406 cases received cochlear implants between December 1985 and April 2007 at Tokyo Medical University (TMU) Hospital. We retrospectively reviewed case notes from 366 patients who had undergone cochlear implantation (215 adults and 151 children) after excluding 40 patients of re-implantation including 13 cases implanted initially at other hospitals. Life-threatening, major and minor complications were examined retrospectively.Major complications occurred following cochlear implantation in 32 patients (8.7%) who had received their initial implant at TMU Hospital. Revision surgery was required for 30 patients. The mean age at implantation was 33 years 6 months (range, 1 year 9 months to 83 years; median, 37 years). The main etiology of deafness was unknown or progressive (113, 52.6%) in adults and congenital (132, 87.4%) in children. The cause of deafness was meningitis in 41 cases (11.2%), and 26 cases (7.1%) were diagnosed with idiopathic sudden deafness.Flap-related problems (including middle ear infection and/or flap necrosis) developed in 13 cases (3.6%), with 12 cases (7 adults, 5 children) requiring re-implantation. Electrode slip-out occurred in 8 patients (7 adults, 1 child). All adult cases in whom electrodes slipped out underwent implantation before 1994, while the child (1 pediatric case) was operated in 2003. All cases required re-implantation and most cochlear implantations were performed using the modified split-bridge technique after 1997. Six patients (4 adults, 2 children) experienced device failure. Four patients experienced electrode problems. Non-surgical major complications included 1 patient with permanent facial nerve paralysis as a result of thermal injury in 1995.The total number of minor medical and surgical complications was 27, representing 7.4% of all operations.Many cases of major complications, including electrode problems and facial paralysis, excluding traumatic device failure were considered avoidable by strict operative and postoperative procedures. Some cases of flap infection and traumatic device failure may not be able to be avoided completely, and every possible care should be taken by implant patients and others involved.

P22.9 Congenital CMV infection and d-bifunctional protein deficiency; a rare cause of deafness and epilepsy

P22.9 Congenital CMV infection and d-bifunctional protein deficiency; a rare cause of deafness and epilepsy

A013 Cochlear implant revision surgery in children

Cochlear implantation has become an effective treatment for many profoundly deaf patients. As with any surgical procedure, a proportion of patients suffer postoperative complications. The aim of this study was to analyze long-term postoperative complications in patients with cochlear implants with a view to improve clinical interventions and propose a consensus for reporting complications.A total of 406 cases received cochlear implants between December 1985 and April 2007 at Tokyo Medical University (TMU) Hospital. We retrospectively reviewed case notes from 366 patients who had undergone cochlear implantation (215 adults and 151 children) after excluding 40 patients of re-implantation including 13 cases implanted initially at other hospitals. Life-threatening, major and minor complications were examined retrospectively.Major complications occurred following cochlear implantation in 32 patients (8.7%) who had received their initial implant at TMU Hospital. Revision surgery was required for 30 patients. The mean age at implantation was 33 years 6 months (range, 1 year 9 months to 83 years; median, 37 years). The main etiology of deafness was unknown or progressive (113, 52.6%) in adults and congenital (132, 87.4%) in children. The cause of deafness was meningitis in 41 cases (11.2%), and 26 cases (7.1%) were diagnosed with idiopathic sudden deafness.Flap-related problems (including middle ear infection and/or flap necrosis) developed in 13 cases (3.6%), with 12 cases (7 adults, 5 children) requiring re-implantation. Electrode slip-out occurred in 8 patients (7 adults, 1 child). All adult cases in whom electrodes slipped out underwent implantation before 1994, while the child (1 pediatric case) was operated in 2003. All cases required re-implantation and most cochlear implantations were performed using the modified split-bridge technique after 1997. Six patients (4 adults, 2 children) experienced device failure. Four patients experienced electrode problems. Non-surgical major complications included 1 patient with permanent facial nerve paralysis as a result of thermal injury in 1995.The total number of minor medical and surgical complications was 27, representing 7.4% of all operations.Many cases of major complications, including electrode problems and facial paralysis, excluding traumatic device failure were considered avoidable by strict operative and postoperative procedures. Some cases of flap infection and traumatic device failure may not be able to be avoided completely, and every possible care should be taken by implant patients and others involved.