Abnormal pinna type and hearing loss correlations in Down's syndrome

Significant hearing loss and external pinna malformations are two of the most common defects evident in Down's syndrome. The external and middle ears are linked embryologically, both arising from the first and second branchial arches. Evidence indicates that the majority of hearing loss in Down's syndrome is conductive in nature, originating from malformations of the middle ear ossicles and/or the eustachian tube. Recent studies also have indicated that hearing loss is a contributing factor to the IQ and learning deficits that afflict most individuals with Down's syndrome. Therefore, an early, external diagnostic feature for predicting conductive hearing loss would be desirable. In the current study, people with Down's syndrome, people with non-Down's mental retardation and control subjects were examined in a clinical environment for the presence of hearing loss and pinna defects. It was found that 90% of the Down's syndrome population had significant hearing loss, compared to slightly more than 50% in the non-Down's group and no hearing loss in the controls. Also, the majority of hearing loss among individuals with Down's syndrome was conductive, while all hearing loss in the non-Down's group was sensorineural. The Down's syndrome population exhibited nearly 3.5 pinna defects per ear, with malformations of the helix being very evident. The non-Down's population exhibited 2.5 pinna defects per ear, with concha defects being the most common.