History: 5-year-old boy with bilateral hearing loss since birth
Findings: Axial and coronal images through the temporal bones demonstrate lack of development of the external auditory canals bilaterally with small middle ear cavities and an ossicular mass closely applied to the lateral walls of the epitympanic spaces. the inner ear structures are normal.
Diagnosis: Bilateral external auditory canal atresia
External auditory canal atresia is one of the more common congenital anomalies of the temporal bone. Patients with this condition typically have malformed pinna and no visible external auditory canal. Atresia of the external auditory canal can be either bony or membranous, and occasionally there is stenosis of hypoplasia rather than a true atresia. The condition is bilateral in up to one-third of patients. External auditory canal atresia is associated with ossicular fusion abnormalities, most commonly fusion of the malleus and incus. The middle ear cavity of often small, and the facial nerve may have an anomalous course. The inner ear structures are usually normal. Bilateral external auditory canal atresia always requires surgery, usually at an early age. Unilateral atresia may not need to be surgically repaired until the teenage years if hearing in the opposite ear is normal.
Aunt Annie’s Pearls
- Atresia or hypoplasia of the external auditory canal is associated with fusion anomalies of the ossicles and malformations of the pinna.