Screening for congenital hearing impairment: time for a change.

The need for the early identification of children with permanent childhood hearing impairment (PCHI), most of which is congenital, has long been recognised in the UK. The early work of the School Medical Service, and of the Ewings in Manchester, supported by key developments elsewhere in the UK, led in the 1960s to a de facto national screening programme. This was configured around a “distraction test” screen performed by health visitors at 7–9 months, and a back up screen at school entry. Although the introduction of the Infant Distraction Test (IDT) probably resulted in a significant reduction in the median age of identification for PCHI, by the early 1980s doubts were being expressed about the performance of the screen, despite its endorsement by the government’s Advisory Committee on Services for Hearing Impaired People. These doubts led to notable and partially successful eVorts by some to improve the IDT by better training, equipment and protocols. However, doubts remained, particularly as the limited data available indicated that for a large proportion of children the age of identification of congenital hearing impairment continued to be very late. In some developed countries, such as Holland, eVort was directed towards a more automated version of the UK IDT, backed up by better information systems. In others, where community services were less well developed—the USA, for example, interest centered on technological developments which might permit hearing screening of neonates. In the 1980s two neonatal screening techniques were developed, one based on the Auditory Brainstem Response (ABR), the other on Transient Evoked Otoacoustic Emissions (TEOAE). In ABR screening clicks are presented to the baby’s ear and the resulting electrical activity generated by the eighth nerve and lower brainstem pathways are picked up by surface electrodes and averaged; in automated versions a machine based decision on the presence or absence of waveforms is made resulting in a pass/refer decision. TEOAEs are generated by an active physiological mechanism in the healthy cochlea, and can be elicited in response to clicks presented to the ear via a lightweight probe. This probe also houses a microphone which picks up the acoustic energy generated by the cochlea and transmitted back through the middle to the outer ear. Multiple clicks are presented, and the responses averaged to generate an ear specific but repeatable waveform. Such TEOAEs are not apparent in ears with middle or inner ear disease. Pass or refer decisions are usually made by the screener on the basis of a combination of displayed statistics. In 1995 the NHS Research and Development Health Technology Assessment programme funded a critical review of the role of neonatal hearing screening in the UK. The review was necessary because of the continuing doubts about the ability of the IDT to deliver early identification of congenital hearing impairment, the technological advances which have made neonatal hearing screening an option, and the great variability in service provision that has resulted in major inequities. The final report of the critical review was presented to the National Co-ordinating Centre for Health Technology Assessment in 1997; copies are available from the MRC Institute of Hearing Research. This article summarises the review, its main recommendations, and the consequent service implications.