Tympanometry screening in developmentally delayed individuals.
Residents of the Huronia Regional Centre for the developmentally disabled (N:900) underwent otoscopic screening (canal "clear" vs "not clear") and tympanometric screening, including tympanometry and physical volume measures (Ss exhibiting Type B tympanograms were classified "hard positive"). Results showed that (1) by otoscopy, 53.2% of all Ss examined had canals "not clear". (2) Overall, degree of retardation was loosely related to prevalence of abnormal otoscopy. (3) The etiologies for mental retardation of "metabolism" and "chromosomal abnormalities" (including all Down's Syndrome cases) were most prone to be in the "not clear" otoscopic category. By tympanometry, 25.8% were classified "hard positive". Overall, conductive disorders as assessed by tympanometry increased significantly with degree of mental retardation. Chromosomal abnormalities yielded a significantly higher proportion of "hard positive" cases (43%) than any other etiology. Identification of sub-populations at risk for conductive disorders, such as those of chromosomal abnormalities and/or more severe developmental delays will enable the employment in the future of more efficient auditory screening techniques.