- Bilateral cases present at birth with respiratory distress.
- Unilateral cases may present later in life with unilateral nasal obstruction or nasal discharge.
- CT scan confirms the diagnosis.
Choanal atresia is a congenital obstruction of the posterior nasal apertures. This abnormality occurs in one out of every 5000–7000 live births and affects females twice as often as males. It can occur unilaterally or bilaterally with unilateral atresia being more common. Choanal atresia has been described as bony, membranous, or mixed membranous-bony, with the mixed membranous–bony atresias being most common and occurring in 70% of cases. Possible etiology of choanal atresia includes persistence of the buccopharyngeal membrane from the foregut, failure of perforation of the nasobuccal membrane, abnormal persistence or location of mesoderm forming adhesions in the nasochoanal region, and misdirection of neural crest cell migration.
Choanal atresia is associated with other anomalies in half of the cases. The most commonly described association is with CHARGE (Coloboma of the eye, Heart malformations, Choanal Atresia, Retarded growth or development, Genital or urinary abnormalities, Ear malformations or deafness). Increased rates of choanal atresia have been associated with abnormalities in vitamin A metabolism and with prenatal use of thionamides (eg, methimizole or carbimizole).
Neonates are obligate nasal breathers during the first 3–5 months of life; therefore, choanal atresia leading to nasal obstruction may present as respiratory distress and require emergent intervention. Infants with bilateral choanal atresia present with a cyclical cyanosis that improves with crying and worsens with feeding. Unilateral choanal atresia occurs more frequently in the right choana and may present later in life with unilateral nasal obstruction and persistent nasal discharge. The initial diagnosis usually occurs upon an examiner's inability to pass a small catheter or flexible endoscope through the choana.
The diagnosis is confirmed with a CT scan of the paranasal sinuses and skull base. Radiographic imaging allows for examination of the entire nasal cavity, helps to characterize the nature and severity of the anatomic deformity, and also differentiates other causes of nasal obstruction. On CT imaging, choanal atresia is diagnosed if the posterior choanal orifice measures less than 0.34 cm unilaterally or if the posterior vomer measures greater than 0.55 cm (Figure 11–2).
CT scan demonstrating left choanal atreasia.
The initial treatment, particularly of bilateral choanal atresia, is to establish a safe airway. Oral airway, McGovern nipple, or intubation can be used as temporary measures. When the patient is stable for general anesthesia, definitive surgical correction of the atresia can be performed.
Several surgical repair techniques have been described. The transnasal approach involves passing dilators under direct vision with either a 120° endoscope or mirror to make an opening in the atretic plate. This technique is fast and involves less blood loss. The transpalatal approach is more often reserved for older patients with unilateral atresia. Although there are better visualization and higher success rates, palate growth can be disrupted, which frequently leads to palate and cross-bite deformities. Endoscopic technique is more difficult to perform in a neonate's nose. An endoscope is used to visualize the atretic plate. The plate is perforated either under direct vision through the nose or using dilators. The opening is then enlarged by removing the posterior part of the septum with back-biting through-cutters, microdebrider, or guarded drill.
To prevent restenosis, stents are placed into the opened choanae and left in place for 2–6 weeks. Application of mytomycin C has been used to reduce postoperative restenosis. However, because of the long-term concerns with the application of a potentially oncogenic medication, routine use is not recommended.
Success rates for surgical repair of choanal atresia range from 55% to 85%. Failure results when the choanae become obliterated by granulation or scar tissue. Recurrences can occur between 2 months and 6 years and often require further surgical correction or dilations. Recently, repeated balloon dilation has been used successfully to treat recurrent choanal atresia.
Ramsden JD, Campisi P, Forte V. Choanal atresia and choanal stenosis. Otolaryngol Clin North Am
. (Review of surgical approaches to management of choanal atresia and choanal stenosis.)