Classification of trace patterns of 226- and 1000-Hz tympanometry in healthy neonates

Objective

Accurate evaluation of middle ear function is a challenge especially in babies referred from newborn hearing screening programs. The aim was to assess the feasibility of tympanometry using 226- and 1000-Hz probe tones in neonates.

Methods

Hearing was evaluated by transient evoked otoacoustic emission (TEOAE) in 96 ears of healthy neonates in well-baby nursery. Babies with risk factors for hearing loss as identified in Joint Committee on Infant Hearing (JCIH, 1994) were excluded. Tympanograms recorded with 226 and 1000 Hz probe tones were analyzed and classified.

Results

Tympanograms were classified according to Method A (Jerger/Liden) and visual classification systems, Method B (adapted from Marchant et al.) and Method C (adapted from Kei et al.), without difficulty. In 72 ears with normal TEOAE, 226 Hz tympanograms were classified as normal in 72 ears in Methods A and B, and 16 ears in Method C. 1000 Hz tympanograms were normal in 68 ears in Method A, 72 ears in Method B and 68 ears in Method C. In 24 ears with abnormal TEOAE, 226 Hz tympanograms were interpreted as normal in most ears (23 ears in Method A, 24 ears in Method B), whereas 1000 Hz tympanograms were abnormal in 13 ears in Method A and 6 ears in Method B, possibly reflecting middle ear dysfunction.

Conclusion

In healthy neonates without risk factors for hearing loss, 1000 Hz tympanograms can be recorded and interpreted. A single-peaked tympanograms was most common in ears with normal TEOAE. In ears with abnormal TEOAE, tympanograms were classified as abnormal more frequently using 1000 Hz than 226 Hz. Implementation of tympanometry using 1000 Hz probe tone in newborn hearing screening programs may provide valuable information regarding middle ear dysfunction that may cause transient conductive hearing loss.