Congenital aural atresia is a birth defect that consists of absence or a severely narrow external ear canal. The eardrum membrane and hearing bones are commonly also deformed and other abnormalities may co-exist in the middle ear. It is almost always accompanied by a malformed (microtia) or absent (anotia) external ear. Atresia and microtia are common congenital malformations, with the incidence of microtia reported to be 0.5 to 3 per 10000 live births, and congenital aural atresia is reported in 55% to 93% among individuals with microtia. Microtia is unilateral in most patients, more commonly in boys and more commonly on the right side.
While children with bilateral hearing loss are known to be at increased risk of speech and language delays as well as poor performance in school, the clinical significance of single sided hearing loss is not universally recognized. Common thought has been that children with single sided hearing loss were thought to develop speech and language normally and most have not received hearing aids. However, a number of small studies of children with single sided hearing loss have shown delays in word acquisition in younger children, increased grade failure rates, and a higher probability of needing speech and language services. Significant deficits for these children exist in language comprehension and oral expression.
While these findings are significant, it is unclear if they can be extrapolated to children with unilateral congenital aural atresia because most of the children in prior studies of single sided deafness had profound sensory hearing loss whereas the children with congenital aural atresia typically have normal inner ears and their problem is limited to the middle ear and external ear canal. Also unclear was whether the side of the congenital ear canal atresia might impact development of speech and language.
For this study, the authors reviewed records by audiologists, speech pathologists, and psychologists looking at the incidence of speech and/or language delay, the incidence of needing speech therapy, and other educational interventions. Also checked were parental reports of social problems.
Seventy-four children were identified with singled sided congenital absence of the ear canal: 48 on the right-side; 19 on the left-side, and 7 with bilateral absence. Children with this birth defect demonstrated high rates of utilizing speech therapy (86% among bilateral, 43% among unilateral). Reports of school problems were more common among children with right-sided (31%) than those with left-sided ear canal abnormalities(11%). Special educational interventions were common in all groups (33% right, 21% left, 43% bilateral). In the case of bilateral AA, all children who received additional interventions were enrolled in schools for the hearing impaired, without any other specified learning deficiencies.
Conclusions and Relevance Children with single sided abnormalities of the outer ear canal are at greater risk of speech and learning difficulties than previously appreciated, with rates similar to children with unilateral inner ear (sensory) hearing loss. This group of children has an obvious need for more study of how best to assist them.