External auditory canal aplasia/hypoplasia

External auditory canal aplasia/hypoplasia refers to the congenital absence (aplasia) or underdevelopment (hypoplasia) of the external ear canal, the passage that leads from the outer ear (pinna) to the eardrum (tympanic membrane). This condition is also known as aural atresia or external auditory canal atresia/stenosis. It results from abnormal development of the first branchial groove during embryonic life and primarily affects the auditory system. The condition may occur unilaterally (one ear) or bilaterally (both ears) and leads to conductive hearing loss because sound cannot travel normally through the ear canal to reach the middle ear structures. It is frequently associated with other external and middle ear malformations, including microtia (underdevelopment of the outer ear), ossicular chain abnormalities, and occasionally inner ear anomalies. External auditory canal aplasia/hypoplasia can occur as an isolated finding or as part of broader syndromic conditions such as Treacher Collins syndrome, Goldenhar syndrome (oculo-auriculo-vertebral spectrum), or branchio-oto-renal syndrome. The key clinical feature is hearing loss, which can significantly impact speech and language development, particularly when bilateral. Diagnosis is typically made at birth or in early infancy through clinical examination and confirmed with imaging studies such as high-resolution computed tomography (CT) of the temporal bones, which helps delineate the anatomy of the ear canal, middle ear, and inner ear. Audiological evaluation, including auditory brainstem response (ABR) testing, is essential to assess the degree and type of hearing loss. Management depends on the severity and whether the condition is unilateral or bilateral. Early hearing rehabilitation is critical, especially in bilateral cases, and may include bone-conduction hearing aids (such as bone-anchored hearing aids or softband devices) to ensure adequate auditory input during critical periods of speech and language development. Surgical reconstruction of the ear canal (canaloplasty or atresiaplasty) may be considered in selected patients, typically after age 5-6 years, based on favorable middle ear anatomy as assessed by CT imaging. Patients require long-term follow-up by a multidisciplinary team including otolaryngologists, audiologists, and speech-language pathologists.

Inheritance

Variable

Can be inherited in different ways depending on the underlying gene

Age of Onset

Neonatal

Begins at or shortly after birth (first 4 weeks)

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