Choanal Atresia/Pyriform Aperture Stenosis

Introduction

Nasal obstruction in the neonate can lead to severe respiratory distress and failure to thrive if not properly identified and treated. Newborn infants are obligate nasal breathers; therefore, nasal airway obstruction has significant downstream effects. Cyclic apnea, cyanosis, and respiratory distress temporarily relieved by crying should elicit a high index of suspicion for nasal airway obstruction. In the neonate, this can be caused by bilateral choanal atresia or pyriform aperture stenosis (PAS).

Choanal atresia is an excess of mesenchymal tissue that creates an atretic plate that separates the posterior nasal cavity from the nasopharynx. It is believed that the pathogenesis is a persistence of the buccopharyngeal membrane during weeks 4 to 11 of development or a failure of the oronasal membranes to rupture. There are also additional anatomic anomalies that accompany choanal atresia that can compromise the nasal airway. These include septal deviation to the obstructed side, medial bowing of the lateral nasal wall, medialized pterygoid plates, widened vomer, and a narrow nasopharynx. Unilateral atresia is more common than bilateral with the right side more common than the left. Thirty percent are purely bony, and 70% are mixed membranous and bony atresia. Up to 49% of patients with bilateral choanal atresia have an associated congenital malformation. CHARGE syndrome (coloboma, heart disease, choanal atresia, retardation of growth, genital hypoplasia, and ear anomalies), Treacher Collins Syndrome, Crouzon’s, Apert’s syndrome, or Trisomy D have all been found to be associated with bilateral choanal atresia. Unilateral choanal atresia may not be recognized until later in childhood, adolescence or early adulthood. Patients can present with unilateral nasal obstruction, mouth breathing, rhinorrhea, sinusitis, or loss of their sense of smell.

Congenital nasal PAS is a rare form of nasal airway obstruction. It is caused by medial positioning or overgrowth of the medial nasal process of the maxilla. The pyriform aperture is the narrowest part of the nasal airway. Therefore, any decrease in size can cause significant nasal obstruction in the neonate. These patients have a similar presentation to infants with bilateral choanal atresia. They have nasal obstruction, inability to pass a nasogastric tube, respiratory distress, cyanosis, and feeding difficulty. The diagnostic criteria for PAS is a width less than 11 mm measured as the total width between the medial aspect of the maxilla at the level of the inferior meatus. In addition to PAS, the nasal cavity is also found to have narrowing of the midnasal and choanal regions. Other associated findings with PAS include median central incisor, a triangular-shaped palate, and a medial palatal ridge. If the patient is found to have a median central incisor on computed tomography (CT) scan, then a magnetic resonance imaging (MRI) should be performed to evaluate for holoprosencephaly spectrum disorders. Genetic work up is also recommended if a central neurologic anomaly is suspected.

Key Operative Learning Points

• Endoscopic technique can provide excellent visualization of the choana and entire nasal cavity/airway.

• Resection of the hypertrophied vomer and posterior septum is essential in preventing restenosis

• Postoperative stenting has not been shown to improve outcomes in choanal atresia repair patients. However, stenting should strongly be considered/used in the neonate after repair to provide a patent nasal airway. They are also recommended for use in patients with CHARGE association. The stent provides a reliable nasal airway that gives immediate relief to neonatal nasal obstruction while the operative site is healing.

• Syndromic patients (CHARGE) have a lower success rate due to their cardiopulmonary medical issues. They can have a flat skull base and less room for repair in the nasopharynx. They have a higher chance of requiring a tracheostomy in early infancy to establish a stable airway.

• Routine endoscopy and removal of crusting and granulation 7 days after surgery improves postoperative outcomes.

• Infants (<28 days old) likely require several postoperative dilations after trans-nasal repair. This can be performed in the operating room or in the office with ureteral dilators. Balloon dilators can also be used in the operating room (OR) or office setting.

• Mitomycin C has not been shown to decrease restenosis rates in large meta-analysis studies. However, some studies show a trend toward reduced granulation tissue formation and decreased re-stenosis in the neonate population when used during initial surgical repair. This should be considered in the neonate population.

• Failure to reduce the inferior turbinates in PAS can also lead to failure and the need for surgical airway intervention.

Preoperative Period

Bilateral choanal atresia can lead to a medical emergency with cyclical desaturations, cyanosis, and distress in the neonate. It must be expeditiously evaluated and treated to prevent respiratory distress and prolonged intubation. A McGovern nipple can be used to help maintain the infant’s airway. This can also allow the infant to start feeding in most cases. If the infant continues to have respiratory distress with the McGovern nipple in place, then laryngotracheal mask (LMA) or endotracheal intubation may be required. In some circumstances, a tracheostomy may need to be performed if the definitive repair needs to be delayed due to other health issues (i.e., cardiac disease). PAS can lead to the same clinical presentation due to the bilateral nasal obstruction it causes. Unilateral choanal atresia can often be managed less urgently. Most infants are able to maintain a nasal airway without a McGovern Nipple or intubation until a repair is performed.

Inability to pass a 6 French nasogastric catheter through the nasal cavity/nasopharynx and absence of fogging of a mirror when placed beneath the nose all point to possible choanal atresia/PAS. This should then be evaluated by an Otolaryngologist who can perform a bedside nasal endoscopy to look for patency of the nasal cavity and posterior choanae. If the flexible scope cannot be passed through one or both sides of the nose, then a CT scan is indicated to evaluate the nasal cavity and choanae. The CT scan can also be used to evaluate the inner ear for anomalies associated with many of the related syndromes.

PAS should initially be treated medically, and surgery is then recommended if the conservative management does not provide an adequate nasal airway in the neonate. Conservative management includes using saline nasal drops, oxymetazoline spray, nasal corticosteroid drops, temporary stenting of the anterior nares if possible with a nasal airway, and use of a McGovern nipple. The traditional surgical management of PAS is a sublabial drill out procedure with stenting. Recent studies have also reported addressing the inferior turbinate as it arises from the lateral border of the pyriform aperture and can contribute to nasal airway narrowing/obstruction. Dilating the pyriform aperture using ureteral/cervical dilators or balloon provides a nondestructive surgical option to open the pyriform aperture. There are no current literature guidelines for when surgical management of PAS is required. Some authors suggest that nasal obstruction with respiratory distress, apnea, or feeding difficulties requires surgical management, and other studies have suggested that width <5.7 mm is associated with surgical management.

All patients should be consented for a direct laryngoscopy and rigid bronchoscopy as part of a complete airway evaluation at the start of the surgical procedure. There is a risk of laryngomalacia, tracheomalacia, and subglottic stenosis in this cohort of patients. Identifying a secondary airway lesion can be imperative in postoperative management of these patients. Pre and postoperative gastroesophageal reflux disorder (GERD) management is also important in these patients.