Introduction to Choanal Atresia

Choanal atresia is a congenital disorder characterized by the narrowing or complete obstruction of the posterior nasal apertures (choanae). This condition affects approximately 1 in 5000-8000 live births, with a female predominance. Choanal atresia can be unilateral (more common) or bilateral, and may be bony, membranous, or mixed in nature.

The condition was first described by Johann Rodolphus in 1755, but it wasn't until 1854 that Emmert reported the first successful surgical repair. Understanding this condition is crucial for pediatricians, otolaryngologists, and neonatologists, as prompt diagnosis and management can be life-saving, particularly in bilateral cases.

Pathophysiology of Choanal Atresia

The exact etiology of choanal atresia remains unclear, but it is believed to result from a failure of the bucconasal membrane to rupture during fetal development. This typically occurs between the 6th and 11th week of gestation. Several theories exist regarding its pathogenesis:

• Persistence of the buccopharyngeal membrane from the foregut
• Abnormal mesoderm adhesion in the choanal region
• Misdirection of mesodermal flow due to local factors

Choanal atresia can occur as an isolated defect or as part of syndromic conditions, most notably CHARGE syndrome (Coloboma, Heart defects, Atresia choanae, Retarded growth and development, Genital hypoplasia, Ear anomalies/deafness). Genetic factors, including mutations in the SMAD3 gene and chromosomal abnormalities, have been implicated in some cases.

The obstruction in choanal atresia is typically:

• 90% bony
• 10% membranous
• Often a combination of both

Clinical Presentation

The clinical presentation of choanal atresia varies depending on whether the condition is unilateral or bilateral:

Bilateral Choanal Atresia:

• Presents as a medical emergency in newborns
• Cyclic cyanosis that worsens with feeding and improves with crying
• Respiratory distress and airway obstruction
• Inability to pass a nasogastric tube

Unilateral Choanal Atresia:

• May go undiagnosed until later in childhood
• Unilateral nasal obstruction and discharge
• Difficulty feeding
• Mouth breathing and snoring

Associated anomalies are present in up to 50% of cases, emphasizing the importance of a thorough physical examination and consideration of syndromic associations, particularly CHARGE syndrome.

Diagnosis of Choanal Atresia

Diagnosis of choanal atresia involves a combination of clinical suspicion and imaging studies:

Clinical Diagnosis:

• Inability to pass a small catheter through the nose into the pharynx
• Absence of airflow through the nostrils when breathing
• Failure to fog a metal mirror placed under the nostrils

Imaging Studies:

• CT Scan: Gold standard for diagnosis
  • Provides detailed information about the type and extent of the atresia
  • Helps in surgical planning
• Nasal Endoscopy:
  • Allows direct visualization of the choana
  • Can be challenging in neonates due to small nasal passages

Differential diagnosis includes other causes of nasal obstruction such as pyriform aperture stenosis, nasal turbinate hypertrophy, and nasolacrimal duct cysts.

Management of Choanal Atresia

Management of choanal atresia depends on the severity and laterality of the condition:

Emergency Management (Bilateral Cases):

• Secure airway: Oropharyngeal airway or intubation if necessary
• McGovern nipple or other oral airway device

Surgical Management:

• Transnasal Approach:
  • Preferred method in most cases
  • Can be performed endoscopically
  • Lower complication rates and faster recovery
• Transpalatal Approach:
  • Used for revision cases or very thick atretic plates
  • Provides better exposure but has higher morbidity

Postoperative Care:

• Stenting of the newly created passage (controversial)
• Regular nasal irrigation and debridement
• Close follow-up to monitor for restenosis

Timing of surgery is crucial: bilateral cases require immediate intervention, while unilateral cases can often be managed electively. The choice of surgical approach depends on the patient's age, anatomy, and surgeon's preference.

Complications and Follow-up

Despite advances in surgical techniques, choanal atresia repair can be associated with several complications:

• Restenosis (most common complication)
• Septal perforation
• Synechia formation
• Palatal fistula (in transpalatal approach)
• Eustachian tube dysfunction

Long-term follow-up is essential and typically involves:

• Regular nasal endoscopy to assess patency
• Monitoring of nasal symptoms
• Assessment of facial growth and development
• Evaluation for associated conditions, particularly in syndromic cases

Prognosis is generally good with appropriate management, but patients may require multiple procedures to maintain nasal patency. Early intervention and multidisciplinary care are key to optimizing outcomes in children with choanal atresia.