Choanal Atresia

Choanal atresia is a congenital obstruction of the posterior nasal aperture (the choana). A bony (about 90 percent, with mixed bony membranous in 70 percent) or membranous (10 percent) plate lies between the nasal cavity and the nasopharynx.

It occurs in about 1 in 5,000 to 8,000 live births, with a female predominance (about 2:1). It is unilateral in two thirds (more often on the right) and bilateral in one third. Bilateral atresia is a neonatal emergency because infants are obligate nasal breathers (until 3 to 6 weeks of age).

The cause is thought to be one of the following:

• failure of the buccopharyngeal membrane to rupture
• persistence of the nasobuccal membrane of Hochstetter
• abnormal persistence of mesoderm in the choanal area
• misdirection of neural crest cell migration, with involvement of retinoic acid signalling and fibroblast growth factor receptor genes (FGFR2)

Maternal exposure to methimazole, carbimazole and valproate has been associated.

About 50 percent of patients (up to 70 percent for bilateral) have other anomalies. CHARGE syndrome (Coloboma, Heart defects, Atresia choanae, Retardation of growth, Genital hypoplasia, Ear anomalies and deafness; CHD7 mutation) is the most important. About 10 to 20 percent of patients with bilateral disease have CHARGE.

Other associations: Treacher Collins syndrome, Apert and Crouzon syndromes, DiGeorge (22q11.2 deletion) and VACTERL association, and Tessier cleft.

• Bilateral: severe respiratory distress at birth with cyclical cyanosis. Cyanosis at rest is relieved by crying, when the mouth opens and the baby breathes through the mouth. It recurs when the crying stops and the mouth closes.
• Bilateral, additional features: apnoea, stridor, feeding difficulty (cyanosis when feeding because of the need to breathe and suckle), failure to pass a nasal catheter, and mucus accumulation in the nasal cavity.
• Unilateral: often diagnosed late (in childhood, or even adults). Chronic unilateral nasal obstruction and persistent unilateral mucoid or mucopurulent rhinorrhoea since birth, with an absence of misting on the affected side.
• Associated features: CHARGE (eye coloboma, heart disease, ear malformation, cranial nerve palsy, genital hypoplasia), craniofacial anomalies, cleft palate.
• Examination: absence of airflow through one or both nostrils (a cold metal spatula held under the nostrils does not mist, or a wisp of cotton does not move).
• Examination: inability to pass an 6 to 8 Fr catheter 3 to 4 cm beyond the nasal opening (the nasopharyngeal distance). Anterior rhinoscopy finds pooled secretions.

• Bedside: inability to pass a 6 Fr or 8 Fr feeding catheter through the nose into the oropharynx (more than 32 mm from the nostril in a term newborn); absent nasal airflow on one or both sides.
• Nasal endoscopy: after suctioning and decongestion (oxymetazoline 0.05 percent drops), a blind pouch or an atretic plate at the posterior nasal cavity with the pooled secretions, which confirms the diagnosis.
• CT of the nose and skull base (axial, 1 mm slices; after suctioning of secretions and decongestion) is the diagnostic standard. It shows a bony (or mixed) plate and the thickness of the plate. It helps with surgical planning and shows the presence of associated anomalies.
• CT also shows narrowing of the posterior nasal cavity: a vomer thickening above 0.5 cm and medialisation of the lateral wall. A posterior choanal width below 0.34 cm in the newborn indicates stenosis.
• Evaluation for associated anomalies, particularly CHARGE syndrome: echocardiography, ophthalmological examination, audiometry (auditory brainstem response), renal ultrasound, genetic testing (CHD7), and other relevant tests.
• Pre-operative assessment: anaesthetic evaluation, echocardiography, swallowing assessment.

• Initial resuscitation for bilateral atresia (neonatal emergency): secure an oral airway (a McGovern nipple, an oropharyngeal airway, or a modified teat with a cut tip to keep the mouth open), oxygen, and positioning prone with the head elevated.
• If this fails, endotracheal intubation may be required (oral intubation). A tracheostomy is rarely needed (in 5 to 10 percent, for severe associated anomalies, or in failed surgery).
• Gastric tube feeding (orogastric) until the airway is secure, with prevention of aspiration.
• Surgical repair is the definitive treatment:
  • Timing: bilateral atresia should be repaired as soon as the infant is stable (within the first days to weeks of life, usually the first 2 to 4 weeks).
  • Unilateral atresia is repaired electively at an older age (age 2 to 5 years, or later, with weight above 10 kg, or earlier when symptoms are significant). A larger operative field gives better results with less restenosis.
  • Transnasal endoscopic repair (the preferred approach): perforation of the atretic plate with a drill, microdebrider or a curette under endoscopic guidance. Remove the posterior vomer and widen the choanal opening with the removal of the medial pterygoid plate.
  • A nasal mucosal flap technique (flaps from the nasal septum and the lateral nasal wall; the Hadad-Bassagasteguy flap) provides coverage of the exposed bone and reduces restenosis.
  • Mitomycin C topical 0.4 to 1 mg/mL applied for 2 to 5 minutes to the surgical site reduces scarring and restenosis (used by many surgeons; evidence is limited).
  • Stenting after surgery with silicone or endotracheal tubes (size 3.0 to 3.5 mm) for 2 to 6 weeks (some surgeons avoid stents with flaps), to maintain patency. Stents are fixed with sutures, with regular saline irrigation, suctioning and checks for blockage and granulation tissue.
  • Transpalatal approach (historic): used in older children with recurrent stenosis, with a higher risk of palatal growth disturbance and fistula.
• Postoperative care: intensive care or close monitoring for airway, and saline drops and suction every 2 to 4 hours.
• Postoperative drugs: topical steroid drops (dexamethasone ciprofloxacin or mometasone) for granulation tissue. Antibiotics during stent time (amoxicillin clavulanate 25 to 30 mg/kg per day of the amoxicillin component in 2 to 3 divided doses).
• Anti-reflux therapy (omeprazole 1 mg/kg daily or lansoprazole 0.7 to 1.4 mg/kg daily) for the laryngopharyngeal reflux, which promotes restenosis.
• Follow up: endoscopy at 2 weeks, 4 to 6 weeks, and then at 3, 6 and 12 months.
• Revision surgery or balloon dilatation for restenosis (in about 20 to 40 percent, or more in bilateral, bony and CHARGE patients). Topical mitomycin, repeated dilation, and stenting for recurrent cases.
• Management of the associated anomalies in a multidisciplinary approach (cardiology, ophthalmology, audiology and hearing aids, genetics, speech and swallowing therapy, and developmental assessment).
• Prognosis: good in isolated cases, and for unilateral disease. Syndromic cases, with other anomalies (CHARGE syndrome), have a higher morbidity and mortality.