TYMPANOMETRY AND OTOACOUSTIC EMISSIONS IN A COHORT OF SPECIAL CARE NEONATES

Otoacoustic emission (OAE) screening and oto-admittance testing (678 H z probe tone) were performed on both ears of 84 special care neonates, as part of a larger study of middle-ear effusion in neonates and infa nts. OAE results, tympanometry, and acoustic reflex results are all st rongly and significantly associated. No evidence was found of any matu rational effects in the results. Based on the findings, a tentative cl assification scheme for neonatal tympanograms is suggested. We conclud e that 678 Hz tympanometry is a useful indicator of middle-ear status in very young babies, and that middle-ear effusion does strongly affec t OAEs in neonates. OAEs are also strongly affected by negative middle -ear pressure (MEP), and mean MEP in ears failing OAE screens was sign ificantly more negative than in those passing. The prevalence of abnor mal tympanometry, which may indicate middle-ear effusion or dysfunctio n, was 20% of ears (29% of babies) in this group. It appears that midd le-ear effusion could account for about half of the ears failing an OA E screen on the special care baby unit. We also find that length of st ay on the special care baby unit is an important risk factor for devel opment of middle-ear effusion: those on the unit for over 30 days have about four times the risk of bilateral abnormal tympanometry.