Ear disease and hearing sensitivity in mentally retarded children

The population screened for mental retardation consisted of 12,882 children, 8 years old. One hundred and fifty-one mentally retarded children were clinically studied. No borderline case was included. One hundred and one children were randomly chosen to form a control group. On clinical examination the children were 9-10 years old. Tympanograms were obtained from 206 children (81.8%). The tympanograms in respect to 30.9% of ears were classed as abnormal in the case of mentally retarded children, but in only 17.8% of non-retarded children. The difference is statistically significant (P less than 0.01). Pure tone audiometry was performed in 213 children. Thirty children were tested in open sound field, and 9 children remained untested. The examinations revealed 31 children with decreased hearing sensitivity (24 with conductive impairment, 7 with sensorineural hearing loss). Three children with profound sensorineural hearing loss and 21 with conductive impairment were among the mentally retarded. The threshold values were also examined using two-way analysis of variance. The groups were classified according to findings in psychological tests and according to the clinical findings in relation to the tympanic membrane. These two sets of findings constituted the two independent variables. These two factors had a highly significant (P less than 0.001) effect, but their interaction was not significant. Mentally retarded children clearly have middle ear disease much oftener than non-retarded children, and such ear disease is accompanied by decreased hearing sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)