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Choanal Atresia

  • Eimear PhelanEmail author
  • John Russell
Living reference work entry
  • 242 Downloads

Abstract

Choanal atresia or stenosis is the most common craniofacial defect of the nose. In choanal atresia there is either partial or complete obstruction of the one or both openings (posterior choanae) connecting the nasal cavity to the pharynx. Bilateral choanal atresia presents at birth with life-threatening airway obstruction, as neonates are obligate nasal breathers. The etiology of choanal atresia is largely unknown. Infants with bilateral choanal atresia will require stabilization of their airway soon after birth. Surgical repair should be performed early in bilateral choanal atresia if there are no medical contraindications.

Keywords

Choanal atresia Choanal stenosis Airway obstruction 

Introduction

Choanal atresia or stenosis is the most common craniofacial defect of the nose occurring in 1in 8000–10,000 births (Burrow et al. 2009; Harris et al. 1997). In choanal atresia there is either partial or complete obstruction of the one or both openings (posterior choanae) connecting the nasal cavity to the pharynx. In the neonate the most common cause of nasal obstruction is choanal atresia or stenosis (Figs. 1 and 2). Bilateral choanal atresia presents at birth with life-threatening airway obstruction , as neonates are obligate nasal breathers. The reflexes to facilitate breathing through the open mouth in response to nasal obstruction develop only weeks to months after birth – although an infant will mouth breath if the mouth is opened either during crying or with the help of an artificial airway.
Fig. 1

Image demonstrating choanal atresia

Fig. 2

Image demonstrating choanal stenosis

Epidemiology

  • 1 in 8000–10,000 births

  • Unilateral more common than bilateral 2:1 (right side > left)

  • More common in females than males

  • Affects all races equally

  • Chromosomal abnormalities found in approximately 6% infants

Embryology

The nasal placodes are derived from ectoderm and appear during the third week of gestation. Around week 5, these placodes invaginate into pits that extend posteriorly from the nasal cavity, which is separated from the oral cavity by a thin nasobuccal membrane. This eventually ruptures at approximately 6 weeks forming the posterior choanae.

Suggested Etiology

The etiology of choanal atresia is largely unknown. However, a number of theories have been proposed including the following:
  • Persistence of the buccopharyngeal membrane

  • Failure of the bucconasal membrane of Hochstetter to rupture

  • Medial outgrowth of vertical and horizontal processes of the palatine bone

  • Abnormal mesodermal adhesions forming in the choanal area

  • Misdirection of mesodermal flow due to local factors

More recently, some studies have suggested that the use of certain antithyroid medications (i.e., methimazole, prodrug carbimazole) during pregnancy may increase the risk of having an infant with choanal atresia. It is not clear whether this is due to the drug itself, maternal thyroid disease, or abnormal thyroid hormone levels (Barbero et al. 2008; Clementi et al. 2010). Lee et al. demonstrated a significant association between low levels of thyroid hormone at birth and the risk of choanal atresia among infants with no known thyroid disease (Lee et al. 2012). Further studies are needed to clarify the role of thyroid hormones in the development of choanal atresia.

The obstruction of the posterior choanae may be bony, membranous, or both. Ninety percent of children with choanal atresia have a bony component, and 10% are membranous. However, modern imaging would suggest a mixed bone/membranous obstruction in 70% and a pure bony obstruction on 30% (Brown et al. 1996). The choanal orifices normally measure >3.7 mm in children younger than 2 years, and the vomer does not exceed 3.4 mm in children younger than 8 years. Computed tomography (CT) typically demonstrates medial bowing and thickening of the lateral walls of the nasal cavity, which are fused with the enlarged vomer. Some degree of narrowing of the bony nasal passage and vomer thickening are usually present with membranous atresia (Hasegawa et al. 1983).

Clinical Features

Infants are initially obligate nasal breathers for the first few months of life. Nasal obstruction frequently causes severe respiratory distress (especially if bilateral). They often present with snorting and nasal flaring. Cyanotic episodes are frequent which may be alleviated by episodes of crying (permits ventilation – infant turns pink when crying as the infant breathes through an open mouth – a phenomenon known as cyclical cyanosis) . This is classical in infants with bilateral choanal atresia. In addition, in children with choanal atresia, there is a high incidence of concomitant craniofacial and developmental anomalies, e.g., CHARGE association.

The CHARGE association (Coloboma, Heart defect, Atresia choanae, Retarded growth, Genital hypoplasia, Ear anomalies) is associated with choanal atresia in 30% of cases. Additional malformations have been reported in up to 49% of children with choanal atresia. This rises to approximately 75% in bilateral choanal atresia cases (Freng 1978a). Other associated syndromes include CHARGE, Crouzon, Pfeiffer, Antley-Bixler, Marshall-Smith, and Treacher Collins (Burrow et al. 2009; Harris et al. 1997; Freng 1978a).

It is essential to establish a secure airway which will need to be done before any investigative procedures. If there no associated lung or laryngotracheal abnormalities, the placement of an oral airway or McGovern nipple (a nipple from a feeding bottle with nipple end opened to allow respiration) may be sufficient. Alternatively, orotracheal intubation with ventilatory support may be required to maintain adequate ventilation. Most infants with unilateral choanal atresia are asymptomatic and may not present until later or adulthood with unilateral nasal obstruction, unilateral nasal discharge, or as an incidental finding.

Diagnosis

The initial diagnosis can be suggested by the inability to pass an 8F nasal catheter through the nose into the pharynx, which can be confirmed by the inability to see patent posterior choanae or pass a flexible nasal endoscope into the postnasal space. Other simple tests which can be performed include assessing for fogging of a mirror/metal spatula when held at the nostril or using a stethoscope to listen for airflow at the nares. However, fine-cut (1–2 mm thick) CT images of the paranasal sinuses and skull base with the bone and soft tissue windows provide valuable information on the anatomy of the posterior nasal cavity and posterior choanae such as the composition and severity of the obstruction. The nasal passages should be suctioned prior to performing the CT to eliminate retained secretions that can obscure the true thickness of the soft tissue component of the anomaly (Brown et al. 1996; Hasegawa et al. 1983; Keller and Kacker 2000). Imaging will also differentiate choanal atresia from other causes of bilateral nasal obstruction such as pyriform aperture stenosis and bilateral nasolacrimal duct cysts.

Management

Infants with bilateral choanal atresia will require stabilization of their airway as outlined above. Surgical repair should be performed early in bilateral choanal atresia if there are no medical contraindications. Infants with unilateral choanal atresia can usually wait until they are older (>1 year) unless it is causing significant airway issues and will therefore require early intervention. A number of surgical techniques have been described; the first repair was performed in 1854 by Carl Emmert. Transnasal puncture using urethral sounds was initially performed blindly. However, with the availability of endoscopic technology, the vast majority of choanal atresia repairs are performed endoscopically using powered instruments (Ramsden et al. 2009).

Endoscopic Technique

This approach allows for excellent visualization of the operative field. A Boyle-Davis mouth gag is inserted and a suture placed through the uvula and clipped to assist with retraction of the soft palate. A 120° 4 mm endoscope is passed through the mouth into the nasopharynx, and a view of the posterior surface of the obstructed choanae is obtained. The nasal cavity is decongested with 1:10,000 adrenaline patties, and the atretic plate is injected with 1% lignocaine with 1:200,000 adrenaline. The atretic plate is then perforated with a small urethral sound under endoscopic visualization which is passed through the mouth at the time of perforation. The urethral sound is passed in an inferior medial direction to avoid damage to the sphenoid or skull base. Progressively larger sounds are introduced to dilate the perforated atretic plate. The endoscopic drill (Medtronic) is then inserted through the nose until it reaches the nasopharynx. The drill has a specially designed sheath to prevent trauma to normal tissue/structures in the nasal cavity. The drilling is performed medially over the vomer and laterally over the medial pterygoid plates. The posterior aspect of the vomer is also removed using a backbiter forceps. This creates a common cavity posteriorly which minimizes the risk of restenosis. Currently the authors insert bilateral soft stents (nasopharyngeal airway stents) which are cut to size so they sit at the nostril anteriorly and extend 2–3 mm posteriorly beyond the newly formed choanae. These are secured anteriorly with silk sutures (through flange of stent only) which are then taped to the infants’ face. Postoperatively these stents are kept patent by the use of regular saline flushes and humidified air. These stents are left in situ for 1 week. The child is then brought back to theater for removal plus or minus removal of granulation tissue if required. It is the authors’ practice to routinely schedule the child for a second endoscopic examination under general anesthetic as a day-case procedure approximately 1 week later, during which patency of the newly formed choanae is assessed and granulations removed as necessary. It is common for a child post choanal atresia repair to require multiple microdebridements and dilatations – one large series reported an average of 4.9 procedures (Samadi et al. 2003). Other transnasal techniques have been described including the use of mucosal flaps which have been suggested to improve reepithelization (Dedo 2001; Nour and Foad 2008). However, the authors’ experience is that these flaps are difficult to perform in a newborn’s nose.

Transpalatal Technique

This technique provides good exposure to the posterior choanae/nasopharynx and was the mainstay of surgical repair until the advent of endoscopic technology. A U-shaped incision was made on the hard palate 5 mm from the dental arch. A posteriorly based subperiosteal flap is raised to gain access to the nasopharynx. The inferior vomer is encountered and removed prior to drilling of the lateral atretic plate. This technique remains useful in children with a low skull base or small nasopharynx or where an endoscopic technique has failed. This approach is associated with higher complication rates than the endoscopic technique such as postoperative pain, palatal fistula, and reduced midface growth leading to a high-arched palate and dental malocclusion which occurs in approximately 50% of patients (Freng 1978b).

Controversies in Choanal Atresia Management

Nasal Stents

Currently there is evidence in the literature which supports both stenting and no stenting post choanal atresia repair. Nasal stenting post choanal atresia repair began as a way to prevent the restenosis seen after simple transnasal puncture. Current advocates of stenting suggest that nasal stents aid in the support and healing of mucosal flaps around the neo-choanae and allow for nasal patency until scarring has occurred. Others use nasal stents in infant patients due to concern of postoperative nasal airway obstruction due to edema. There are variable stenting practices among those who stent with regard to duration and stent material used with overall good success rates of >80% (Bedwell and Choi 2012).

The use of postoperative stenting carries with it associated risks including:
  • Pressure by the stents can cause pressure necrosis of the columella or alar rim, causing cosmetic deformity.

  • Stents that are too tightly secured to the septum can likewise cause septal cartilage necrosis and permanent perforation.

  • Stents may also contribute to localized tissue inflammation and infection, leading to increased pain, granulation tissue, and synechia formation.

In addition stents demand intensive management by caregivers with frequent irrigation and suctioning to prevent obstruction with secretions (Hengerer et al. 2008; Van Den Abbeele et al. 2002).

Those who advocate for no stenting argue that due to the use of endoscopes and smaller nasal instruments, there is less damage to surrounding mucosa and less risk of exuberant granulation tissue, thus obviating the need for stents. Schoem describes a series of 13 children with a mix of unilateral and bilateral atresia. Seven of these patients were found to have some granulation or synechiae formation at a routine endoscopy 3–4 weeks after the initial repair. After microdebrider excision of the granulation tissue, all were patent at the last follow-up (12 months post repair). Only four patients from this series did not have to return to the operating room and were found to be patent via flexible endoscopy in the office (Schoem 2004). Ibrahim et al. reported on a substantial series of 21 patients managed without postoperative stents. Three patients required revision, with one patient having a second revision, for a success rate of 86% (Schoem 2004). In both series, aggressive nasal irrigation regimens with saline as well as a steroid-containing nasal drop were used. Schoem added oral antibiotics and steroids. Patients were able to feed immediately after surgery, and hospital stays were relatively short (Schoem 2004; Ibrahim et al. 2010).

Mitomycin C

Mitomycin C is an aminoglycoside which by the bacteria Streptomyces. It cross-links DNA and causes cell apoptosis. When applied to healing tissue, it has an antiproliferative effect which inhibits fibroblast growth and proliferation. Mitomycin C is widely used in ophthalmic and laryngeal surgery to prevent scar formation and was proposed for use in choanal atresia surgery to reduce restenosis. However, several small studies have not shown it to be effective in improving long-term outcomes, and there is concern on reuse of a potentially oncogenic medication in children (Kubba et al. 2004).

Outcomes

The primary outcome measure in choanal stenosis is restenosis and the need for reoperation. Reported revision rates vary from 0% to 36% (Ramsden et al. 2009; Kubba et al. 2004). Restenosis rates appear more likely in patients who undergo surgery in the neonatal period for bilateral disease and suffer from gastroesophageal reflux disease. Favorable outcomes may be predicted by the absence of associated facial anomalies, higher weight at the time of surgery (>2.3 kg), and larger stent size (Kubba et al. 2004; Teissier et al. 2008).

Conclusion and Future Directions

Choanal atresia or stenosis is the most common craniofacial defect of the nose. Bilateral choanal atresia presents at birth with life-threatening airway obstruction, as neonates are obligate nasal breathers. Infants with bilateral choanal atresia will require stabilization of their airway as previously discussed. Surgical repair should be performed early in bilateral choanal atresia if there are no medical contraindications; infants with unilateral choanal atresia can usually wait until they are older (>1 year) unless it is causing significant airway issues. A number of surgical techniques exist for the management of choanal atresia in the newborn as discussed (Eladl and Khafagy 2016; Kwong 2015). Due to the rarity of this condition, there is still controversy as to whether nasal stents should be used or not (Strychowsky et al. 2016).

Cross-References

References

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Copyright information

© Springer-Verlag GmbH Germany 2016

Authors and Affiliations

  1. 1.Our Lady’s Children’s Hospital CrumlinDublinIreland

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