[Mass screening of deafness in neonates using otoacoustic emissions]

There is no clinical sign of hearing loss in the infant. Defective language acquisition and altered voice quality always occur late making early diagnosis essential for therapeutic management of deaf children. Subjective assessment of behavioral is highly dependent on the experience of the examinator and cannot be used as an effective routine method. Electrophysiological recordings of otoacoustic emissions have the advantage of allowing objective measurement. Otoacoustic emissions originate in the inner ear. A quantity of energy is transmitted via the tympanic membrane which acts as a microphone, allowing recordings in the external auditory canal. In certain infants these emissions are spontaneous and can be used to detect certain types of hearing loss. Stimulation is required however for screening tests. Recording provoked otoacoustic emissions is simple. A small probe in placed in the external auditory canal. This probe carries two microphones, one which emits clicks recorded by the other captor microphone. The examination lasts approximately 15 minutes, including the time needed to explain the procedure to the mother. There are two possible results. The presence of recorded otoacoustic emissions confirms that the inner ear is normal. If the absence of emissions is confirmed at a second examination, an evoked potential recording is required to identify the hearing loss. This safe, simple and reliable method for detecting hearing loss in infants is recommended for screening programmes during the neonatal period.