Choanal atresia refers to a lack of formation of the choanae, the openings providing communication between the nasal cavity and nasopharynx. It can be unilateral or bilateral.
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Epidemiology
It frequently presents in neonates where it is one of the commonest causes of nasal obstruction in this age group. There is a recognized female predilection. The incidence is estimated at ~1:5000-8000.
Associations
Syndromic associations include
Other associations include
Clinical presentation
Presentation depends on whether it is uni- or bilateral. Unilateral choanal atresia presents late and can be asymptomatic or present with rhinorrhea. Bilateral atresia can present with neonatal respiratory distress as infants are obligate nasal breathers. Another finding is failure to pass a nasogastric tube beyond 32 mm.
Approximately two-thirds of cases are unilateral 6,7.
Pathology
Structurally there are two main types:
osseous: ~90% 2
membranous: ~10%
General pathogenesis includes:
teratogenic effects caused by early pregnancy use of antithyroid drugs 8
Radiographic features
CT
Assessment with axial CT may show:
a uni- or bilateral posterior nasal narrowing with an obstruction
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airway less than 3 mm
measurement is done at the reference level of the pterygoid plates in the axial plane
an air-fluid level above the obstruction point
thickening of the vomer
medial bowing of posterior maxillary sinus
Treatment and prognosis
Options include:
endoscopic perforation (for membranous types)
full choanal reconstruction
Differential diagnosis
On axial CT consider:
