Acoustic immittance findings in acute otitis media.

This study sought to evaluate the sensitivity of tympanometry and acoustic reflex measurement for identifying acute otitis media. Acute otitis media was diagnosed via case history and biphasic pneumo-otoscopy in 103 children (161 ears) ranging in age from four months to 17 years (mean age, 5.6 years) who had subjective complaints of only one to three days. Of the 161 ears with diagnosed acute otitis media, the tympanogram was categorized as flat in 102 ears (63%), shallow/rounded in 18 ears (11%) and negative in 17 ears (11%). Of particular interest was that 15 ears (9%) were classified tympanometrically as normal, and 19 ears exhibited a high positive pressure peak greater than + 100 mm H2O. Based on these findings, tympanometric sensitivity for identifying acute otitis media was only 74.5% which is considerably less than that reported for persistant middle ear effusion. When test sensitivity was recalculated after parceling out the 42 ears with segmental disease, however, accuracy for identification increased to 89%. Results for acoustic reflex measurement were equally discouraging with test sensitivity being only 71%. These results suggest that the use of acoustic immittance measures may be of limited value for identifying acute otitis media.