Audiologic profile of infants at risk: Experience of a Western Sicily tertiary care centre

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Abstract

Objective

To identify the incidence of sensorineural hearing loss (SNHL) on infant at risk and to classify the degree and type of hearing loss describing the main causes associated in Western Sicily. To compare single TEOAE and combined TEOAE/ABR techniques studying the referral rate, the false-positive and false-negative rates through concordance test (κ coefficient), sensitivity (TPR) and specificity (TNR) for each protocol.

Methods

From January 2010 to June 2011, 412 infants at risk, ranging from 4 to 20 weeks of life, transferred to Audiology Department of Palermo from the births centers of Western Sicily, underwent to audiological assessment with TEOAE, tympanometry and ABR. The following risk factors were studied: family history of SNHL, consanguinity, low birth weight, prematurity, cranio-facial abnormality and syndromes associated to SNHL, respiratory distress, intensive care in excess of 5 days (NICU), pregnant maternal diseases, perinatal sepsis or meningitis, hyperbilirubinemia, ototoxic drugs administration.

Results

Forty-seven infants (11.41%) were diagnosed with SNHL; median corrected age at final audiological diagnosis was 12 weeks. SNHL resulted moderate in 44.68%, severe in 10.64% and profound in 21 cases with a significant difference in family history and NICU infants (p < 0.0001). As the number of coexisting risk factors increases, the percentage value of SNHL in infants (χ2 = 12.31, p = 0.01, r2 = 0.98) and the degree of hearing loss (χ2 = 13.40, p = 0.0095, r = 0.92) also increase. The study of single TEOAE and combined TEOAE/ABR showed a statistical difference (χ2 = 14.89, p < 0.001) with a low concordance value (κ = 0.87) confirming the importance of combined techniques for NICU group (κ = 0.86) where four cases (0.97%) of auditory neuropathy were diagnosed.

Conclusion

This study demonstrates the necessity to implement a neonatal hearing screening program in Western Sicily because of the high percentage of SNHL in infants at risk. Family history of HL is an independent significant risk factor for SNHL easily diagnosed through single TEOAE technique. Combined TEOAE/ABR is the gold standard for NICU babies which are at risk for auditory neuropathy. Coexisting risk factors are an additional risk factor for HL.

Introduction

According to world statistics research, hearing loss (HL) is one of the most common congenital anomalies, occurring in ∼1–3 cases per 1000 newborn infants in the well-infant population while, in certain “higher risk” populations this value could increase 10- to 50-fold, varying from country to country. Normal hearing (NH) is one of the central nervous system's most essential tools for creating the physiological processes of integration, abstraction and creation of “internal speech”, which is a necessary foundation of the thought process; such an early diagnosis and intervention, before six months of age, is effective in allowing children with congenital hearing loss to acquire appropriate cognitive and spoken language skills [1], [2], [3], [4]. The potential benefits of early detection can only be realized if an effective newborn hearing-screening program is performed, especially on infant at risk. The 2007 Position Statement from the Joint Committee on Infant Hearing (JCIH) confirmed that neonates who are in Intensive Care Units (ICUs) for >5 days, or who have risk factors and a shorter stay, undergo hearing screening with transient evoked otoacoustic emissions (TEOAEs) and (automated) auditory brainstem response (ABR) testing, that is recommended for screening because of the increased occurrence of neural (auditory neuropathy/dyssynchrony) loss in this population, compared with well infants [1]. If the neonates do not pass the tests, then a full diagnostic audiological assessment is to be performed by an experienced audiologist [1].

Risk indicators associated with permanent congenital, delayed-onset, or progressive hearing loss in childhood given in the 2007 Position Statement [1] expand those of older risk registries [5]. Although a family history of hearing loss (syndromic or nonsyndromic), cranio-facial abnormalities, prenatal infections, hyperbilirubinemia requiring exchange transfusion, and culture-positive sepsis remain risk factors, other independent neonatal risk factors have been reported [1]. These risk factors include a need for ventilation, use of oxygen supplementation, respiratory failure, low Apgar scores, acidosis, use of ototoxic drugs including furosemide (especially with high serum creatinine levels), treatment for hypotension, patent ductus arteriosus ligation, hyponatremia, and noise [6], [7], [8], [9], [10], [11], [12], [13]. Interaction among risk factors has been shown [11].

Even if an newborn hearing screening (NHS) is implemented in most parts of the developed world as an essential component of neonatal care, in Italy there is no stipulated modality for achieving the goal of early hearing detection in individual regions. In fact, the initiatives are still left to individual hospitals that have activated locale programs based on the collaboration of the single birth centers and the Audiology Sections.

The Department of Audiology of Palermo University represents the main speech and hearing third level centre in Western Sicily; waiting for a NHS sponsored by Regional Health Department, it daily performs an audiological assessment to those infants at risk born in Western Sicily and transferred from NICUs and/or regular nurseries to our specialized area.

The aim of this study was to identify the incidence of permanent childhood hearing impairment (PCHI) on population at risk; to classify the degree and type of hearing loss describing the main causes associated with SNHL in infants at risk in Western Sicily focusing on the importance of a suitable and adequate hearing assessment especially for those populations at risk for permanent hearing impairment. The final purpose of this study was to investigate the referral rate and the false-positive and false-negative rates for the single TEOAE technique and the combination of TEOAE/ABR technique in infant at risk; comparing two screening protocols, we attempted to find the better technique that could give high sensitivity (the proportion of children without SNHL who have a negative test, i.e. are correctly identified by the screening protocol) and acceptable specificity (the proportion of children without SNHL who have a negative test, i.e. are correctly identified by the screening protocol) for hearing screening/diagnosis of infants at risk.

Section snippets

Materials and methods

This study was carried out by the Department of Audiology, University of Palermo and investigated all infants transferred from the births centers of Western Sicily, with the purpose to identify risk indicators for permanent congenital, delayed-onset, or progressive sensorineural hearing loss, from January 2010 to June 2011; the population consisted of 424 infants, 248 males and 176 females, ranging from 4 to 20 weeks of life at the time of first appointment. Following Ethical Committee

Results

The total number of infants at risk examined from January 2010 to June 2011 was 412, corresponding to 171 females (41.50%) and 241 males (59.50%) with a male:female ratio = 1.40; the age of infants at first diagnostic ABR measurement, ranged from 4 to 20 weeks of life, with no statistical difference among the sex (t = 0.86; fd = 410; p = 0.38). Of the 412 infants examined, 239 (58.01%) resulted positive for a specific risk factor while in 173 cases, corresponding to 41.99%, multiple risk factors were

Discussion

In the general population, a newborn every 500–1000 births presents permanent hearing impairment (HI) greater than the incidence of other diseases routinely screened at birth [15], [16]. Moreover, in certain ‘higher risk’ populations, this incidence could increase to 8–100 cases per 1000 infants. The importance of deafness for the public health comes from its tendency to cause sequelae and complications such as irreversible delay in speech and cognitive development. To prevent these

Conclusion

With an incidence of 11.41% of SNHL in infants at risk this study demonstrates the necessity to implement a NHS program in Western Sicily; according to JCIH, the gold standard for NICU babies which are at risk for ANSD is the combined TEOAE/ABR technique. As data literature reports, ‘family history’ of HI is an independent significant risk factor for SNHL easily diagnosed through single TEOAE technique that is able to detect the cochlear genesis of HI with the same accuracy as ABR technique (p = 

Conflict of interest

The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.

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