Profound permanent hearing impairment in childhood: causative factors in two European countries

Cochlear implantation in the very young child: issues unique to the under-1 population

Since the advent of cochlear implantation, candidacy criteria have slowly broadened to include increasingly younger patients. Spurred by evidence demonstrating both perioperative safety and significantly increased speech and language benefit with early auditory intervention, children younger than 12 months of age are now being successfully implanted at many centers. This review highlights the unique challenges involved in cochlear implantation in the very young child, specifically diagnosis and certainty of testing, anesthetic risk, surgical technique, intraoperative testing and postoperative programming, long-term safety, development of receptive and expressive language, and outcomes of speech perception. Overall, the current body of literature indicates that cochlear implantation prior to 1 year of age is both safe and efficacious.

Improved diagnostic effectiveness with a sequential diagnostic paradigm in idiopathic pediatric sensorineural hearing loss

OBJECTIVES

To determine whether a stepwise diagnostic paradigm is more diagnostically efficient and cost-effective than a simultaneous testing approach in the evaluation of idiopathic pediatric sensorineural hearing loss (SNHL).

DESIGN

Prospective prevalence study.

SETTING

Tertiary referral children's hospital.

PATIENTS

Consecutive children (n = 150) presenting with idiopathic SNHL in the last 2 years.

INTERVENTIONS

All children were evaluated with full diagnostic evaluations including GJB2 screens, temporal bone computed tomography scans, and laboratory investigations.

MAIN OUTCOME MEASURES

1) Diagnostic yields of GJB2 screens, imaging, and laboratory results per SNHL category; 2) Cost analysis comparing a sequential versus a simultaneous testing approach.

RESULTS

Overall, 12.0% of patients had biallelic mutations in the GJB2 gene, whereas 30% of patients had an abnormality on temporal bone scan. Laboratory testing did not reveal the SNHL etiology in any patient. While maintaining diagnostic accuracy, significant cost savings were inferred by using a sequential diagnostic algorithm. Our data show children with severe to profound SNHL should first be tested with a GJB2 screen, as opposed to those with milder SNHL, who should undergo imaging as the initial testing step. In patients with initially positive GJB2 or imaging screens, logistic regression analysis significantly predicted negative results on further testing.

CONCLUSIONS

A stepwise diagnostic paradigm tailored to the level of the hearing loss in children with bilateral SNHL is more diagnostically efficient and cost effective than the more commonly used full, simultaneous testing approach. Laboratory investigation should not be routine but based on clinical history.

GJB2 and GJB6 Mutations in 165 Danish Patients Showing Non-Syndromic Hearing Impairment

Thirty-two genes causing non-syndromic hearing impairment (NSHI) have been cloned, including GJB2 and GJB6 encoding the gap junction subunits connexin 26 and connexin 30, respectively. One mutation in GJB2, 35delG, accounts for a large percentage of GJB2 hearing impairment in Southern Europe whereas a considerably lower frequency has been reported from Northern European populations. Recently, a 342-kb deletion implicating GJB6 was found in 22 out of 44 NSHI patients of Spanish origin with only one mutated allele of GJB2. We report the first study of GJB2 and GJB6 mutations in Danish patients with NSHI. We tested 165 individuals and found GJB2 mutations in 16 individuals. The deletion implicating GJB6 was found in two individuals out of 9 heterozygous for GJB2 mutation. Furthermore, we screened 509 unselected samples from the Danish newborn population for the 35delG mutation in GJB2. We found 9 samples heterozygous for 35delG and 11 samples heterozygous for mutations leading to amino acid variants in GJB2 protein. In conclusion, our data are in accordance with results from other Northern European populations. Furthermore, our data on the GJB6 deletion suggest that routine screening for this deletion could help to explain hearing impairment in some Northern European NSHI patients heterozygous for a mutation in GJB2.

Etiología de la hipoacusia severa/profunda bilateral pre/perilocutiva en cantabria

OBJECTIVE

To know the etiology of preiperlingual bilateral hearing loss in children.

MATERIALS AND METHODS

All the patients diagnosed with bilateral severe/profound, pre or perilingual hearing loss at Sierrallana and Marqués de Valdecilla Hospitals (Cantabria, Spain) during the last 20 years were included in this study.

RESULTS

A hundred patients were diagnosed with bilateral severe/profound pre/perilingual hearing loss. The most frequent etiology was hereditary (49%), followed by severe perinatal hypoxia (11%), ototoxicity (5%), meningitis (3%), hyperbilirubinemia (3%) and rubella (2%). In 21% of cases was not known.

CONCLUSIONS

The two most frequent etiologies found in severe/profound hearing loss in children in our area were hereditary and non infectious perinatal problems. Infectious disease were scarce. Will decrease when genetic test were used as clinical basis.

Provision of hearing aid services: a comparison between the Nordic countries and the United Kingdom

About one in five adults has some form of hearing impairment. This paper reports on a survey which found significant variation in the provision of hearing aid services across Denmark, Finland, Norway, Sweden and the United Kingdom. Per capita expenditure levels were estimated to vary from under 3 euros in the UK to nearly 10 in Denmark and Norway. Annual figures for the number of people receiving at least one aid varied from around eight per 1,000 in the UK and Denmark to 2.2 in Finland. Over 50% of hearing aid users in Norway and Denmark are estimated to have bilateral aids, compared to under 15% in the UK. Estimates of the number of people who have a hearing aid in these countries are considerably lower than the number who have a hearing impairment. More research is needed to verify the true extent of these differences and their cause.

Epidemiology of hereditary hearing disorders in childhood: a retrospective study in Germany with special regard to ethnic factors

Recent studies have revealed marked differences in the prevalence of hearing impairment in childhood. It remains unknown whether this is caused by geographic, sociocultural or ethnic factors. In order to provide consistent data, 314 children in residence at a school for hearing impaired children of a well-defined German area were investigated retrospectively. We estimated an overall prevalence of .43/1000 of hearing impairment for this area. A striking variability between different nationalities could be observed. For German children, the prevalence was .36/1000, for Turkish 1.04/1000 and for Italian children 1.37/1000. Hereditary hearing losses and, in particular, autosomal recessive caused hearing disorders were the most common cause of hearing impairment in foreign but not in native children. One reason might be the frequency of marriages between relatives resulting from the social isolation of the foreign groups in German society.

Social competence and behavioural problems in children with hearing impairment

The focus in this study is on social competence and behavioural problems in a group (n=57) of hearing-impaired 7- to 12-year-old children. Results were related to hearing status, school placement, and gender. Parent and teacher questionnaires were used to measure two aspects of social competence, prosocial orientation and social initiative, and three aspects of behavioural problems, externalizing, internalizing, and concentration problems. A sample of 214 normally-hearing children was used as a comparison group. Overall, the results showed only minor differences between the two groups, with the exception that the hearing-impaired children showed less social initiative in parent ratings. There were no relationships between social functioning and hearing status or school placement (mainstream vs. special classes for hearing-impaired children) nor any clear pattern of gender differences. These findings indicate that hearing-impaired children in Sweden fare well. The results are discussed in terms of the need for longitudinal studies and possible interventions targeted at social behaviours.

The need for universal neonatal hearing screening--some aspects of epidemiology and identification

The devastating consequences of a congenital/early-acquired hearing disability on the speech language and social development of a child and the estimated prevalence rates of at least 1-1.5/1000 live births of congenital permanent hearing impairment are important health problems. Universal neonatal hearing screening programs have provided the opportunity to detect neonates with permanent congenital hearing loss, and thus initiate auditory rehabilitation before the age of 3 mo. Universal neonatal hearing screening represents secondary prevention of hearing impairment/deafness, and the world-wide documented delayed identification of children with congenital/early-acquired hearing impairment will no doubt be improved with the implementation of universal neonatal hearing screening programs.