Review of a high risk register for congenital or early-onset deafness

Comprehensive diagnostic battery for evaluating sensorineural hearing loss in children

OBJECTIVE

Selection of diagnostic tests for children with sensorineural hearing loss (SNHL) is influenced by clinical suspicion. Testing results reported in the literature are similarly biased. We evaluate the usefulness of a comprehensive diagnostic battery for each child.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary care university hospital.

PATIENTS

A total of 270 children referred for severe to profound SNHL between January 2002 and June 2009.

INTERVENTIONS

Results of the following were reviewed: magnetic resonance imaging, computed tomography, renal ultrasound, electrocardiography, fluorescent treponemal antibody absorption test, connexin 26 sequencing, genetic consultation, and ophthalmologic consultation.

MAIN OUTCOME MEASURE

Diagnostic yield of each test was determined.

RESULTS

Each diagnostic test or consultation was completed by at least 95% of patients for whom it was ordered. Magnetic resonance imaging revealed abnormalities explaining SNHL in 24% of patients. Computed tomography showed inner ear anomalies in 18% of patients. Biallelic connexin 26 mutations were found in 15%. Renal ultrasound found anomalies in 4% of patients. Electrocardiography found 1% of patients with prolonged QT intervals. Fluorescent treponemal antibody absorption test result was positive in 0.5%. Genetic consultation found a genetic cause for hearing loss in 25%. Ophthalmologic consultation found abnormalities associated with hearing loss in 8%.

CONCLUSION

Diagnostic radiologic imaging is the highest yielding test for evaluating children with SNHL. Connexin 26 sequencing identifies a nearly nonoverlapping subset of children compared with imaging. Specialty consultations, particularly from a clinical geneticist, can improve diagnostic yield. Other tests, although of lower diagnostic yield for SNHL, can identify important diseases that significantly affect patient health.

[Implantation of a program for the early detection of neonatal hearing loss]

Permanent childhood hearing impairment is a serious public health problem. Identification by screening in the first few months of life has the potential to improve affected children development. Neonatal hearing screening programs endorse the WHO requirement for a cost efficient screening. This paper shows the implementation of a medium-size hospital-based universal newborn hearing screening program using transient evoked otoacoustic emissions. Operational procedures and requirements are discussed. Quality control and results are showed.

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.

Field sensitivity of targeted neonatal hearing screening using the Nottingham ABR Screener

OBJECTIVE

A population of children having bilateral moderate to profound hearing impairment was investigated to find out the number who passed (false negatives) and who failed (true positives) a screening test based on the auditory brain stem response (ABR).

DESIGN

This study of the ABR is a parallel report to Lutman, Davis, Fortnum, and Wood (1997), where the transient evoked otoacoustic emission was examined on a similar but not identical population of at-risk neonates. Hearing screening was undertaken in at-risk neonates (targeted screening) at seven hospitals in the UK using the Nottingham ABR Screener. During the period from January 1988 to December 1993, a total of 6983 neonates had been tested. Assessment of audiological records from the participating centers ascertained that 201 children born between January 1988 and December 1993 had hearing threshold levels in both ears of 50 dB or more, averaged over the speech frequencies 0.5, 1, 2, and 4 kHz. Of these, 51 had completed the ABR screening test. Examination of the ABR records, which included both machine and visual scoring, indicated whether they had passed or failed the screening test.

RESULTS

Forty-six of the 51 hearing impaired babies failed the neonatal ABR screen either on one or both ears (five false negatives), and 42 failed the test on both ears (nine false negatives). This resulted in field sensitivities of 90% and 82%, respectively. Two cases of suspected progressive hearing loss have been included in the numbers of false negative results. The percentage of babies passing the screen on both ears and subsequently having normal hearing (specificity) is typically 93%.

CONCLUSIONS

Neonatal hearing screening in an at-risk population using a highly automated ABR test is a viable and effective tool for identification of hearing impairment. Although the field sensitivity of the test is high, it is unable to identify all babies with a criterion level of hearing loss. There are a number of possible explanations as to the origin of false negative results: configuration of the pure-tone audiogram, a progressive hearing loss, acquired sensorineural or conductive loss, retrocochlear deafness, or an incorrect interpretation of the screening test. Passing a neonatal screening test, therefore, does not exclude the possibility of subsequent hearing impairment and highlights the need for further surveillance.

Changing performance of the Health Visitor Distraction Test when targeted neonatal screening is introduced into a health district

The change in the performance of the HVDT as targeted neonatal hearing screening has been introduced has been examined for the Nottingham district. The records for all children born in the period 1984-1993 within the district and having a permanent hearing loss of > or = 50 dB in the better ear have been examined. The referral route leading to ascertainment of the hearing loss as well as the result of any screening tests were noted. The data shows an increase in the number referred prior to the HVDT, mainly as a result of neonatal screen failure. At the same time there has been a reduction in the sensitivity of the HVDT from 78% in the first half of the decade to 38% for the second half. There are also some indications of an increase in the coverage and the failure rate over the time. Possible reasons for these changes are discussed.

Outcomes of neonatal screening for hearing loss by otoacoustic emission

AIM

To assess universal neonatal screening for bilateral hearing impairments averaging 40 dBHL or worse in the better ear, using transient evoked otoacoustic emission screening (TEOAE) testing.

METHODS

A three year cohort (14,353 infants born from January 1992 to 1995) was screened and subsequently followed up by hearing surveillance methods, including a distraction test screen from 7 months of age. The entire cohort was used to evaluate the outcome of the screen. A subcohort of 8172 district residents was used to evaluate the continuing worth of the distraction test programme.

RESULTS

Nineteen infants (1.3/1000) with a targeted hearing impairment failed the neonatal TEOAE test. Six profoundly deaf infants identified by the TEOAE screen, were fitted with hearing aids at a median age of 16 weeks. One remained without an aid. Of 12 infants with a moderate impairment, only seven accepted hearing aid fitting and the median age of being fitted with an aid increased to 42 weeks. By the time of the analysis 22 children with a targeted hearing impairment (1.5/1000) had been identified from the cohort. Of the three missed neonatally, one was cared for elsewhere, another had a progressive loss, and the third had central deafness. Twenty children were ascertained with a congenital peripheral deafness. Of these, eight (40%) had risk factors identifiable neonatally. Only the child with central deafness was missed by TEOAE screening and subsequently identified by behavioural tests in infancy. The TEOAE screen outperformed the distraction test in terms of processes and yield and was 25% less expensive.

CONCLUSIONS

The analysis confirmed the worth within the district of the TEOAE hearing screen. It will thus be continued as a universal neonatal screen with the distraction test being retained as a selective screen in the latter half of infancy.

Auditory brainstem response screening for hearing loss in high risk neonates

The present paper reports the findings of a 7 year study evaluating the use of the auditory brainstem response (ABR) as the basis of a hearing screening procedure in a group of newborns at increased risk of hearing impairment. A Special Care Baby Unit (SCBU) population of 417 infants with diverse clinical backgrounds and treatment histories was tested for hearing impairment at birth using ABR audiometry. Some 332 passed the original screen at 30 dBnHL test level in both ears. Of the failure group, 18 did not survive and 32 had some degree of hearing impairment confirmed, nine of which were sensorineural in origin. An increased incidence of persistent middle ear disease was also noted in the failure group. A detailed operational analysis demonstrates that provided appropriate pass/fail criteria are adopted, the ABR technique offers excellent sensitivity and specificity for the detection of significant hearing loss in the test population. Furthermore, the study establishes that implementation of an ABR-based screening programme could reduce the average age at detection of permanent hearing loss by 7 months. A cost assessment shows that the introduction of such a targetted screening procedure could be done at a reasonable outlay.

Management and outcome: children fitted with hearing aids in Ireland

The Republic of Ireland has a total population of 3.5 million people, mainly rural or in small towns, a rapidly declining birthrate during 1984 to 1991, and a geographically stable children's population. A unified Audiology Service is provided by the National Rehabilitation Board for the fitting of hearing aids to all children deemed to require them. The current study outlines a database analysis of all children fitted with hearing aids for the first time in 1984 or 1991. Follow-up information on the status (in 1991-1992) of those fitted in 1984 was obtained, with regard to hearing loss, schooling and changes in aiding. Data on severe/profound losses in particular, and the trends in service provision are examined. Similar numbers of children were fitted with hearing aids in the two years sampled, even though the overall degree of hearing loss amongst this population had fallen.

Congenital hearing disability--epidemiology and identification: a comparison between two health authority districts

The objective of the present study was to describe some epidemiological aspects of congenital/early acquired (i.e. in the neonatal period) hearing disability (CEHD) in children born between 1980 and 1990, living in two separate health authority districts, i.e. the Copenhagen City/County; in addition, to evaluate the age at identification of the children, the persons raising suspicion of the hearing loss and the pattern of referral; finally, to compare some epidemiological aspects and the age at identification of similarly defined cohorts of children, born 1970-80. Thus the evaluation can be considered as an audit of the primary health care sector concerning children with CEHD. An identical prevalence rate of CEHD was demonstrated, i.e. 1.5/1000 with a better ear hearing level average at 0.5-4 kHz > or = 25 dB (BEHL 0.5-4 kHz) in both regions and unchanged from 1970-80. The median age at identification in the total cohort was 16/18 months in the City/County, respectively, demonstrating a significantly earlier identification of at-risk children in the County with the opposite pattern in the City. The parents were the first to raise suspicion of their child's hearing disability in 50%/57% in the City/County and only minor differences in the pattern of referral was found in the two regions. The frequency of at-risk children among parents/professionals who first suspected the CEHD showed no significant differences; however, the BEHL 0.5-4 kHz in the children was poorer in the group of parents who first raised the suspicion when compared with the group of professionals. Thus the BEHL 0.5-4 kHz is of significance for the age at identification and for the person raising the suspicion of CEHD. Although an improvement in the early identification of CEHD has taken place, when comparing the 1970-80 cohort and 1980-90 cohort, it is concluded that children with CEHD are identified with a substantial delay and that the line of information both concerning high-risk criteria and general information should be continued and intensified towards both parents and professionals.

Bacterial meningitis and hearing impairment: A prospective study

The purpose of this study is to demonstrate the incidence and the pattern of post-meningitis hearing impairment. A prospective study of 68 meningitis patients was performed. The patients' hearing was evaluated immediately following acute illness and periodically checked for two years. The incidences of the initial sensorineural and conductive deafness were 26.4% and 20.6%, respectively. Two patients (3%) suffered from mixed deafness. No consistent audiometric pattern was found in the cases of sensorineural hearing loss. Serial hearing evaluations demonstrated complete recovery of all cases of conductive hearing loss with only a slight improvement in the low tones noted in one patient with sensorineural hearing loss. No late development of sensorineural loss has occurred.

Neonatal at risk screening and the identification of deafness

From a cohort of 10,686 live births, 322 (3%) were identified as being at risk of a hearing impairment defined as moderate, or worse. These neonates were screened by measurement of auditory brainstem responses. The neonatal at risk screening programme was effective in terms of both yield and cost. The mean age at which hearing aids were fitted was 6 months in the children identified by the neonatal screen. Such a programme is both practicable and useful in a district general hospital. The yield from the neonatal programme was, however, only 43% of the total number of deaf children eventually identified from the cohort. The need to identify more deaf children by a sensitive infant distraction test screening programme remains.