A comparison of tympanometry with 226 Hz and 1000 Hz probe tones in children with Down syndrome.

BACKGROUND

For children with Down syndrome, the incidence of hearing loss may be as high as 78% [1], therefore the American Academy of Pediatrics recommends regular screening for the presence of hearing abnormalities. Tympanometry is used as an indication of middle ear pathology. In our experience, Down's patients' tympanograms do not always correlate with otoscopic findings. Down's patients have joint laxity, small ear canals, anterior tympanic membrane orientation and softer tissue composition, all factors thought to affect tympanogram results in infants. Because the use of the 1000 Hz tympanometry is widely recognized as standard procedure in the evaluation of infants aged 0-6 months, we propose it may have greater reliability in testing patients with Down syndrome.

OBJECTIVE

Compare the results of visual inspection of the tympanic membrane by a Pediatric Otolaryngologist to the results of tympanometry at traditional probe tone (226 Hz) and at the infant probe tone (1000 Hz).

METHODS

Institutional Review Board - approved prospective study of 26 subject-ears in patients with Down syndrome aged 6 months-18 years but recent stable middle ear/Eustachian tube function using physical examination and tympanometric probe tones at 226 Hz and 1000 Hz. Subject-ears were examined with record of "clear of effusion," showed the presence of "fluid," or were to be "excluded." Blinded to ear exam results, tympanometry was then completed with record of which Jerger classification tympanogram was found at each frequency.

RESULTS

Although the sensitivity of each test was 1, the specificity of the 1000 Hz tympanometry (100%) in this study was markedly improved compared to the specificity of the 226 Hz tympanometry (71%) (p=0.016).

CONCLUSIONS

This pilot study demonstrated evidence that tympanometry in children with Down syndrome may be more reliable at 1000 Hz than at 226 Hz in detecting the presence of middle ear effusion beyond infancy. Use of the 1000 Hz probe tone yielded fewer false positives for disease (type B tympanograms in the setting of absent middle ear disease). Further studies of a larger patient population are needed to corroborate these results.