[Otoacoustic emissions screening as early identification of hearing loss in newborns]

Auditory stimulation modulates CXCL12/CXCR4 expression in postnatal development of the newborn rat cochlea

Sensorineural hearing loss is one of the most common sensory deficits. Recently, inner-ear stem cell therapy has been proposed for auditory afferent rehabilitation. CXCR4 is the primary physiologic receptor for CXC chemokine ligand 12 (CXCL12) and the CXCL12-CXCR4 pathway has been implicated in the process of migration, differentiation, and maturation of vertebrate neural stem cells. In this study, we examined changes in the auditory brainstem response and CXCL12/CXCR4 expression in newborn rat cochleae under different acoustic environments by quantitative real-time PCR, western blot, enzyme-linked immunosorbent assay, immunohistochemistry, and immunofluorescence analyses. Rats were divided randomly into three groups: the augmented acoustic environment (AAE) group, the auditory deprivation (AD) group, and the control group. Auditory brainstem response thresholds were markedly increased in the AAE group and in the AD group. Compared with postnatal day 1, the expression of CXCL12/CXCR4 mRNA and protein under normal acoustic conditions was increased on postnatal day 14 and then decreased on postnatal day 28 in the cochlea. However, on postnatal day 28, CXCL12/CXCR4 expression, as well as its spatiotemporal distribution as detected by immunohistochemistry and immunofluorescence assays, was augmented by AAE treatment and inhibited by AD treatment. Therefore, our results confirmed that auditory stimulation influenced the spatiotemporal expression of CXCL12/CXCR4 in newborn rat cochlea, which might help to unravel the role of the CXCL12-CXCR4 pathway in the synaptic contacts and hearing function establishment in rat cochlea development.

Sensorineural hearing loss in children

During the past three to four decades, the incidence of acquired sensorineural hearing loss (SNHL) in children living in more developed countries has fallen, as a result of improved neonatal care and the widespread implementation of immunisation programmes. The overall decrease has been accompanied by a relative increase in the proportion of inherited forms of SNHL. The contribution made by one gene in particular, GJB2, to the genetic load of SNHL has strongly affected the assessment and care of children with hearing loss. These changes in the incidence of SNHL have not been seen in children living in less developed countries, where the prevalence of consanguinity is high in many areas, and both genetic and acquired forms of SNHL are more common, particularly among children who live in poverty. Focused genetic counselling and health education might lead to a decrease in the prevalence of inherited SNHL in these countries. Establishment of vaccination programmes for several vaccine-preventable infectious diseases would reduce rates of acquired SNHL. Although the primary purpose of such programmes is the prevention of serious and in many cases fatal infections, a secondary benefit would be a reduction in disease-related complications such as SNHL that cause permanent disability in survivors.

Control de las repeticiones en un programa de cribado auditivo universal

INTRODUCTION

To evaluate the influence of several factors in the need for retesting in the first stage of a universal auditory screening program, a prospective and statistic study is presented, specially remarking the differences found between two health systems (public and private).

PATIENTS AND METHODS

18,073 children born in the 1999-2004 period were included in the study, in the context of a universal screening protocol based on Otoacoustic emissions and ABR, and distributed into three groups depending on their place of birth (A: public hospital; B: private hospital; C: children from other region).

RESULTS

Significant differences were found between the groups (7.3% retesting in the public system and 2.4% in the private), explained by the fact that in the first group the test was performed in 74.9% of cases within 3 days after birth (when the need for repetition was 7,7%), and in the other groups the exploration was delayed up to 4-10 days in most cases (when retesting was performed only in 4.9%).

DISCUSSION AND CONCLUSIONS

Proportion of retesting in the first stage of a universal screening program is an important factor for the cost estimation of these protocols. We assume that the age at testing varies significantly this factor, and on the contrary, we know that precocious exploration (before the child leaves the hospital) increases the program covering. Therefore we conclude that the test should be delayed only in health systems needing to save resources or not able to test before discharge, and not in those wanting to guarantee the maximum covering.

[Program of hearing loss early detection in newborn infants in Cantabria. Results of the first year of activities]

AIMS

To report the findings in the first year of follow-up of the Cantabrian Program to screen newborn babies for congenital permanent hearing loss.

METHODS

The study population consisted of infants born during a year period in Cantabria (Spain). Universal hearing screening by transient evoked otoacoustic emissions (TEOAE) in 2 stage protocol was performed. Infants with failure scores in these 2 stages and those with risk factors for hearing loss were referred for diagnostic evaluation with auditory brainstem response. Hearing aids were recommended for those infants who had bilateral hearing loss and referrals to infant speech and language rehabilitation.

RESULTS

Out of the 4117 eligible babies, 3987 were studied. One hundred and ten (2.6) had risk factors for hearing loss, 3.5% were referred for audiological assessment and 1.2/1000 were diagnosed as having a permanent hearing loss. The false-positive rate was 0.72% after the two-stage screening procedure was performed. Positive predictive value for permanent hearing loss was 10%.

CONCLUSIONS

During the first year working with the Cantabrian Screening Program for congenital permanent hearing loss in newborn babies, the most part of the proposed aims have been achieved.

[Validation of the otoacoustic emissions in presbyacusis]

INTRODUCTION

With the development of medical technology, human life expectancy has increased. This has increased the incidence of senile pathologies and the associated problems for this people. In the field of otolaryngology, one of these pathologies is presbyacusis. This study attempts to find relationships between presbyacusis and different parameters related to it.

MATERIAL AND METHODS

A cross sectional study was carried out with 59 volunteers aged between 50-89 from different homes for the elderly in the city of Reus. The subjects presented with or without symptoms of deafness. An AOE test was then performed to determine the different parameters. Significant response criteria were: otoemissions with a signal-noise ratio of 3 dB or greater or 65% reproducibility in < 2 bands. The results obtained were analyzed through a computer statistics program (SPSS) and Microsoft Excel for the graphics.

RESULTS

The results of the characteristics of the test are within the acceptable limits of quality. The prevalence of subjects with AOE was 22%, with an average age of the subjects of around 69 years. We did not find statistical differences in the presbyacusis group with respect to the parameters of intensity and reproductability, but there was a correlation in the duration of the test. In the analysis of frequencies in the reproductibility parameters we observed a fall in the 5 KHz. The ratio signal-noise showed a similar tendency. It is necessary to emphasize the worst results in the different parameters from the right ear the left one.

CONCLUSIONS

The AOE offers information in frequencies of 1 and 2 KHz, where we can see a reduction in the reproducibility in the presbyacusis group. We see a longer test time, in the presbyacusis group and this may be used to control the development of the disease.

Correlación entre emisiones otoacústicas y petc. la importancia de su empleo combinado

Auditory Brainstem Response (ABR) of 50 newborn with negative transient evoked acoustic emissions (OEAT) was performed. 54% of them had no family history of sensorineural hearing loss (SHNL) and no risk factors were found. In 70% of cases ABR recording was negative. Follow up did show that 60% of them had normal recordings of hearing and in a 40% different stages of hearing loss were seen. To establish a definitive diagnosis a 1 to 9 month period is necessary.

Detección precoz de sorderas. ejemplo de intervención en salud pública

INTRODUCTION

We present a statistic study comparing all the options we can take to face congenital deafness as a problem of public health.

PATIENTS AND METHODS

We collected and analyzed data obtained between 1991 and 1995, just before our universal screening program started. They were separated into two groups with the 144 children explored using ABR, and the results were compared depending on the option taken in each group (no screening or high risk screening) and finally with those obtained in a universal program.

RESULTS

The establishment of a high risk screening program was followed by a drastic reduction of the severe deafness diagnosis (29.5% to 8%), and also of the mean age of diagnosis (24 to 14 months), which were found statistically significant. The mean age with universal screening is 3 months.

DISCUSSION AND CONCLUSIONS

Early detection of congenital hearing impairment has brought an important advance in the management of this problem of public health minimizing its sequels as the diagnosis is reached earlier. The universal screening of deafness is feasible as based on cheap and easy diagnostic techniques available in any centre, and it must be performed with the rest of Health Children Programs.