Failure to clinically predict NICU hearing loss

The prevalence of congenital and early-onset hearing loss in Jordanian and Israeli infants

The objective of the study was to investigate the prevalence of congenital and early-onset hearing loss, and the influence of the known risk factors for hearing loss on infants in Jordan and Israel. Subjects were a total of nearly 17,000 infants from both countries, including infants with and without risk factors for hearing loss. The hearing screening protocol included distortion product otoacoustic emission, followed in case of repeated OAE referral or high risk (HR) infant by diagnostic auditory brainstem responses. The results indicate that the prevalence and severity of hearing loss amongst Jordanian infants (1.37%) is remarkably higher as compared to the Israeli infants (0.48%). The overall prevalence of bilateral SNHL was seven times more in the Jordanian infants, 18 times in non-risk, and three times in the HR infants relative to the Israeli infants. Risk factors including family history, hyperbilirubinemia, bacterial meningitis, and associated syndromes were more prevalent amongst Jordanian infants. This unique study underscores the importance of sharing and exchanging information to create empirical data to guide health-care providers in adapting protocols to the local constraints in developing countries.

Low prevalence of hearing impairment among very low birthweight infants as detected by universal neonatal hearing screening

OBJECTIVES

To (a) study the prevalence of hearing impairment in a cohort of very low birthweight (VLBW) infants and (b) evaluate the effectiveness of transient evoked otoacoustic emissions (TEOAE) as a first stage in-hospital hearing screening tool in this population.

STUDY DESIGN

The study group was a cohort of 346 VLBW infants born in 1998-2000 at The Sheba Medical Center. The prevalence of hearing impairment in the study group was compared with that of all other newborn infants participating in a universal newborn hearing screening programme during the same period. To evaluate the effectiveness of TEOAE, a control group of 1205 healthy newborns who had no known risk factors for hearing impairment was selected. The results and follow up of hearing screening for these infants were examined retrospectively.

RESULTS

Only one VLBW infant (0.3%) was diagnosed with bilateral sensory-neural hearing loss. In addition, nine infants (2.7%) were diagnosed with conductive hearing loss. Bronchopulmonary dysplasia and low Apgar score were the most significant factors for predicting the occurrence of conductive hearing loss. The percentage of VLBW infants who successfully passed the in-hospital TEOAE screening was 87.2, compared with 92.2% in the full term control group. No false negative cases were detected on follow up.

CONCLUSIONS

The study shows a low incidence of sensory-neural hearing loss in a cohort of VLBW infants and a relatively high incidence of conductive hearing loss. TEOAE screening was found to be an effective first stage in-hospital hearing screening tool in this population.

The otolaryngologist's role in management of hearing loss in infancy and childhood

This article reviews the role of the otolaryngologist-head and neck surgeon-in the diagnosis and treatment of hearing loss in infants and young children. The otolaryngologist is well-versed in the anatomy, physiology, and pathophysiology of the auditory system, as well as the craniofacial syndromes that can involve the head and neck in combination with deafness. In this paper, the various causes of congenital hearing loss are described, as well as the steps required for proper diagnosis. Finally, surgeries used by otolaryngologists to treat childhood hearing loss, their indications, and outcomes, are discussed.

Cochleosaccular pathology after perinatal and postnatal asphyxia: histopathologic findings

OBJECTIVE

This study describes the histopathologic findings of a patient with severe bilateral sensorineural hearing loss after perinatal and postnatal hypoxia and asphyxia.

STUDY DESIGN

Histopathologic examination on the temporal bones.

SETTING

The study was performed at the Elizabeth McCullough Knowles Otopathology Laboratory, Division of Otopathology, Department of Otolaryngology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.

RESULTS

Histopathologic examination on the left temporal bone revealed severe atrophy of the organ of Corti throughout the entire cochlea, decrease in the number of the spiral ganglion cells especially in the basal turn, and mild atrophy of saccular macula. In the right temporal bone, similar abnormalities were observed in the inner ear, but the changes were milder than those in the left temporal bone. No other distinct pathologic finding was observed in either ear.

CONCLUSION

These findings suggest that the presence of severe hypoxic ischemia causes cochleosaccular atrophy. To our knowledge, this is the first histopathologic case report describing the long-term effect of perinatal and postnatal hypoxia and asphyxia that produced cochleosaccular abnormalities in the human inner ear.

Neonatal asphyxia, definitive markers and hearing loss

A study of 56 severely asphyxiated infants (8 hearing impaired and 46 normally hearing) was designed to identify specific markers associated with asphyxia which could be related to hearing loss. Sixteen variables, including such items as: one- and five-minute Apgar scores, muscle tone, use of a ventilator, prolonged stay in the NICU, hypoxic-ischemic encephalopathy (HIE), other organ damage, and intra-uterine growth retardation (IUGR) were considered. Results suggested four factors related to asphyxia which are often found in the presence of hearing loss, but none of these was considered a definitive marker or predictor of such a disability. A combination of HIE, seizures, associated organ damage and IUGR should be considered a strong marker for the probability of a sensorineural hearing loss.

Etiology of hearing loss in children. Nongenetic causes

Every child with a hearing loss should have an evaluation to determine the cause of hearing loss. This article focuses on the nongenetic origins of hearing loss, the most frequent of which is the neonatal intensive care unit experience, followed by meningitis, cytomegalovirus, and other infections. Preventable causes such as exposure to ototoxic medications and noise are also discussed in this article.

Hearing screening in at-risk neonate cohort

OBJECTIVE

This prospective study reports on the prevalence of hearing impairment in an at-risk neonatal intensive care unit (NICU) population.

DESIGN

From 1990 to 1997, 942 neonates were screened with transient evoked otoacoustic emissions (TEOAE) and brainstem evoked response audiometry (BERA).

RESULTS

835 Infants passed the primary screen for both ears, 57 for one ear, adding up to 94.7%. Seventeen infants (1.9%) were lost to follow-up. In thirteen infants (1.4%), bilateral hearing impairment above 30 dB was confirmed. While all children with hearing impairment belonged to the group of 820 children receiving aminoglycosides, only one presented no other risk factors. In 11 of the hearing impaired children other anamnestic factors, i.e. dysmorphism, prenatal rubella or cytomegaly, family history of hearing loss or severe peri- and postnatal complications seem to be more probable causes of the identified hearing loss.

CONCLUSIONS

From our data, aminoglycosides seem not to be an important risk factor for communication related hearing impairment, when serum levels are continuously monitored, as occurred in our cohort. After adjustment for other risk factors, birth weight between 1000 and 1500 g and a gestational age between 29 and 31 weeks were no predictive markers for hearing impairment. It might be speculated that the improved medical treatment in a Neonatal Intensive Care Unit (NICU) reduces the probability of hearing impairment for those two groups. Conductive hearing loss as a possible additional cause for hearing impairment was not studied in detail, but the high percentage of malformations detected (four out of 13 hearing impaired infants) demands further monitoring, close follow-up, counselling and adequate treatment.

The Rhode Island Hearing Assessment Program: experience with statewide hearing screening (1993-1996)

OBJECTIVE

The objective of this study was to evaluate key outcomes of a universal hearing screen/rescreen program for all births with transient evoked otoacoustic emissions in all 8 maternity hospitals in the state of Rhode Island over a 4-year period.

STUDY DESIGN

This was a retrospective analysis of the hearing screen/rescreen refer data collected prospectively for 53,121 survivors born in Rhode Island between January 1, 1993, and December 31, 1996. Primary outcomes included the first-stage refer rates, rescreen compliance, diagnostic referral rates, identification rates, and the age of amplification.

RESULTS

During this 4-year time period 11 infants were identified with permanent hearing loss, resulting in an impairment rate of 2 per 1000. The mean age of hearing loss confirmation decreased from 8.7 months to 3.5 months, and the age at amplification declined from 13.3 months to 5.7 months.

CONCLUSION

We conclude that time and experience are important factors in the development and refinement of a universal hearing screen program. Hearing screen outcome data collected over a 4-year period in Rhode Island reveal a steady improvement in the percent of infants completing the 2-stage screen process, the stage 1 and stage 2 refer rates, compliance with rescreen and diagnostic testing, and significant improvement in the age of identification and age of amplification.

Perinatal asphyxia, hypoxia, ischemia and hearing loss. An overview

Birth hypoxia, asphyxia and ischemia have often been thought to be major causes of early hearing loss or deafness. The purpose of the present review is to focus on the role of these particular factors for perinatal auditory disorders. On the whole, only a small proportion of neonatal hearing loss is caused by perinatal factors. The exact etiology of neonatal hearing loss in children with complicated deliveries is difficult to evaluate due to the large number of causative factors that might be involved. After reviewing the literature covering the past 15-20 years, it is not possible to say that we understand the relative importance of different factors and their interactions. However, in the majority of studies, birth asphyxia is not correlated with hearing loss in babies with complicated deliveries Prolonged artificial ventilation, the presence of severe hypoxic ischemic encephalopathy or persistent pulmonary hypertension are important factors. The brain is more susceptible to anoxia than the ear and both are more likely to be damaged after prolonged pre-, peri- and postnatal hypoxia-ischemia than pure hypoxia during delivery. Perinatal hypoxia is more likely to cause a temporary hearing loss than a permanent one. Preterm babies are more vulnerable than term babies. The total number of risk factors, e.g. medicated by total length of stay in the neonatal intensive care unit and length of artificial ventilation, is the best predictor of risk for hearing loss of perinatal origin. The similarities between hearing loss and cerebral palsy are pointed out; only 8% of the cases of cerebral palsy are considered to be caused by conditions during delivery.