Choanal atresia (ORPHA:137914)
Choanal atresia (CA) is a congenital anomaly of the posterior nasal airway characterized by the obstruction of one (unilateral) or both (bilateral) choanal aperture(s), with clinical manifestations ranging from acute respiratory distress to chronic nasal obstruction.
Epidemiology
CA has a birth prevalence of approximately 1/11,630 in Europe and it follows a ''2:1'' ratio, namely female to male and unilateral to bilateral CA.
Clinical description
CA is a congenital disorder that consists of a unilateral or bilateral bony or membranous septum between the nose and nasopharynx. In bilateral CA (see this term), neonates present at birth with acute respiratory distress requiring orotracheal intubation or placement of an oropharyngeal cannula. Nasotracheal intubation is not possible. Neonates with bilateral CA can also present with a history of multiple failed extubation attempts, especially in those with secondary airway issues. Spontaneous survival with a bilateral CA is possible but exceptional. In unilateral CA (see this term), infants can be asymptomatic often until the first respiratory infection. The most common presentation is persistent unilateral nasal obstruction or persistent mucoid rhinorrhea. CA can either occur in an isolated form or associated with other congenital deformities such as in CHARGE syndrome, Crouzon disease, Down syndrome, Treacher-Collins syndrome, 22q11.2 deletion syndrome (see these terms) or polydactyly. Bilateral CA is more common in patients with other congenital anomalies while unilateral CA occurs more frequently in isolated cases.
Etiology
The following hypotheses are thought to result in developmental failure of the nasal cavity to communicate with the nasopharynx: persistence of the buccopharyngeal membrane from the fetal foregut; abnormal persistence of mesoderm forming adhesions in the nasochoanal region; abnormal persistence of the nasobuccal membrane of Hochstetter; or misdirection during neural crest cell migration. Prenatal exposure to maternal hyperthyroidism treated with methimazole may also be associated with CA development.
Diagnostic methods
Initial clinical evaluation includes introduction of a 6 or 8 French suction catheter via the nostrils, methylene blue dye test, cotton wisp test, and laryngeal mirror test. Flexible nasal endoscopy after mucous suctioning allows direct visualization of the atretic plate in the choana. Definitive evaluation is achieved with a computerized tomography scan which shows thickening of the medial portion of the pterygoid plates and enlargement of the posterior portion of the vomer, with or without membranous involvement. Tomography may also detect an associated malformation of semi-circular canals as found in CHARGE syndrome.
Differential diagnosis
Differential diagnoses include isolated pyriform aperture stenosis, nasolacrimal duct cyst (see these terms), turbinate hypertrophy, septal dislocation and deviation, antrochoanal polyp or nasal neoplasm.
Management and treatment
The goal of initial treatment for infants with bilateral CA is to maintain an adequate airway via the oral route. An oral airway or a feeding nipple with large holes to facilitate air flow can be used. If a patient still fails to maintain an adequate airway, endotracheal intubation must be performed. A tracheostomy may be required in patients with severe comorbidities but it is not necessary in cases of isolated (even bilateral) CA. Definitive surgical correction by nasal endoscopic approach is performed when appropriate and when feasible (weight >2kg). Given the relatively low morbidity of unilateral CA, definitive treatment is delayed until a later age (>18 months of age), when possible, as the chance of successful surgical repair increases with age.
Prognosis
CA (mainly the bilateral form) is a life-threatening condition and treatment cannot be delayed. In both unilateral and bilateral cases, restenosis necessitating reoperation is common.

                            Last update: 
                            February 2016


                            - Expert reviewer(s): 
                            Pr Nicolas LEBOULANGER