A hearing screening programme for infants from a neonatal intensive care unit in a South African provincial hospital

Abstract

The field of early detection and intervention of hearing loss in neonates and infants has been marked by a growing international body of research investigating hearing screening programmes, protocols and outcomes of early detection for hearing loss. In South Africa, screening for neonates and infants in general and particularly for hearing loss is not common practice and is not meeting the needs of the South African population, with very few infants identified with hearing loss early in life. The Year 2002 Hearing Screening Position Statement recommends an intermediate step toward universal screening in the form of Targeted Newborn Hearing Screening (TNHS) as an option for developing countries with limited resources. The Neonatal Intensive Care Unit (NICU) provides a starting point for TNHS because it encompasses a number of risk factors for hearing loss. A combined descriptive and exploratory research methodology was followed to provide a comprehensive perspective on longitudinal hearing screening for NICU neonates and infants at a provincial hospital in South Africa. The quantitative methods included a structured interview to compile risk factor information. Immittance measurements used included acoustic reflex measurements, 226 Hz and 1000 Hz tympanometry. Automated Otoacoustic Emission (AOAE) as well as Automated Auditory Brainstem Response (AABR) screening was conducted. Routine follow-up visits at three month intervals were booked if a subject passed the screen and a follow-up screening for further testing was booked if a subject referred the screening. A total of 49 neonates and infants as well as mothers were enrolled in the first year and followed up for the second year of data collection period. The results indicated that the NICU had potential as platform for TNHS in South Africa. The high incidence of risk factors reported is more when compared with developed countries and highlights the importance of hearing screening in the at risk population for a developing country. The results confirmed reports that 226 Hz probe tone tympanometry produces erroneous responses in young infants. A high correspondence between high frequency tympanometry and AOAE results was found and underlines the need for differential diagnosis to accurately detect middle ear effusion and/or sensorineural hearing loss in neonates and infants. The unilateral AOAE refer rate (7%) was within range of the reported values for initial screening at discharge from the NICU. AABR results indicated a relatively high unilateral refer result (24%) and may be attributed to irritability and restlessness. The highest referral rates in the current study were recorded during the second and third visit and may be attributed to the presence of middle-ear pathology in older infants. The perceptions of mothers emphasized the lack of awareness regarding hearing and hearing loss in South Africa. Lack of knowledge may be a contributing actor to poor compliance with screening follow-up. Despite prevailing challenges, such as a low follow-up return rate, lack of awareness regarding the benefits of early detection of hearing loss, the effect of middle ear effusion on screening results, the cost of hearing screening and different priorities of the national healthcare system, such as Human Immunodeficiency Virus, demonstrated the NICU promise as platform for TNHS in South Africa. TNHS programmes may serve as starting point to direct universal neonatal hearing screening programmes in South Africa.