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Address reprint requests and correspondence: Michele M. Carr, DDS, MD, PhD, FRCSC, Department of Otolaryngology-Head and Neck Surgery West Virginia University, PO Box 9200, Morgantown, WV 26501.
Choanal atresia is a relatively rare congenital nasal anomaly that must be repaired to allow infants to adequately breathe and feed. Techniques used in repair have evolved with the development of high-quality optical equipment, such that an endoscopic approach is now most commonly employed. Operative adjuncts include lasers, topical steroids, and stenting. Restenosis is common in the first few years, but this can be improved with dilation.
First described in 1755 by German physician Johann George Roederer, congenital choanal atresia (CCA) is a developmental anomaly where one or both posterior nasal apertures fail to canalize, resulting in persistence of a posterior plate.
(Figure 1). Derived from the Greek word χοάνη meaning “funnel,” this anatomical space is bounded anteriorly and inferiorly by the horizontal plate of palatine bone, superiorly and posteriorly by the sphenoid bone, medially by the nasal septum, and laterally by the medial pterygoid plates. CCA is a rare cause of nasal obstruction, occurring in 1 in 5,000-8,000 births.
Nearly 47% of neonates with CCA have other associated syndromic disorders (ie, Apert, CHARGE, Crouzon, DiGeorge, Pfeiffer, Antley–Bixler, Marshall–Smith, Schinzel–Giedion, and Treacher Collins).
Increased rates of CCA have also been linked with abnormalities in vitamin A metabolism and prenatal use of thionamides (ie, methimazole or carbimazole).
Several theories have been proposed to explain the pathophysiology of CCA, although none have gained universal acceptance. The persistence of the buccopharyngeal membrane from the foregut appears to be the most widely accepted etiology, but failure of the bucconasal membrane of Hochstetter to involute, abnormal mesodermal adhesions forming in the choanae, and misdirection of neural crest cell migration have also reported in the literature.
Figure 1Four-day-old female with bilateral CCA. Axial computerized tomography reveals widening of the posterior vomer, narrowing of the choanal airspace, and intranasal mucostasis secondary to the presence of bony atretic plates.
The diagnosis of bilateral CCA is suspected soon after birth when a neonate presents with cyclical cyanosis, feeding difficulties, and stertor. Unilateral CCA is a more indolent clinical entity which presents as unilateral nasal obstruction with rhinorrhea that fails to resolve, possibly eluding definitive diagnosis for several years. Anatomical variations which occur with CCA include medial displacement of the posterior part of the lateral nasal sidewall, an accentuated arch of the hard palate, and a shortened nasopharyngeal space. Classically, the diagnosis is made after failing to pass a soft suction catheter into the nasopharynx. Nasal airflow can be evaluated by observing movement of a wisp of cotton wool during expiration or misting during a cold spatula test. Flexible fiberoptic nasal endoscopy reveals an intact wall in the posterior nasal aperture. In children with clinical features concerning for a suspected syndrome, further investigation and genetic counseling are warranted. Pertinent differential diagnoses include inferior turbinate hypertrophy, intranasal foreign body, midnasal stenosis, nasal polyposis, piriform aperture stenosis, and septal deviation. Radiographic imaging provides the most reliable method of diagnosis; axial computerized tomography images reveal narrowing of the choanal orifice (<67 mm) or widening of the posterior vomer (>34 mm).
Initial management of CCA in the neonatal period includes placement of an oral airway, a McGovern nipple, and possibly endotracheal intubation. When the patient is deemed a surgical candidate and stable for general anesthesia, definitive CCA repair can safely be performed.
Surgical strategies
Historically, Carl Emmert was the first to describe successful CCA repair in 1854.
Over the last 160 years, a variety of surgical options, including external, sublabial, and transpalatal approaches have all been used in the operative management of this disorder. Concerns regarding facial growth with removal of the vomer via a sublabial approach and maldevelopment of the upper dental arch (ie, anterior crossbite) with the transpalatal technique have prompted consideration of other procedures such as transnasal puncture and endoscopic resection. In all methods, the inherent challenge is to provide adequate mucosal lining to the neochoanae and prevent granulation tissue formation, osteoneogenesis, and subsequent restenosis.
Transnasal puncture
Transnasal puncture using dilators or sounds is a longstanding and safe method to establish a nasal airway. Advantages of this technique include decreased operative time and reduced intraoperative blood loss. After endotracheal intubation, the intranasal cavities are first suctioned free of secretions and decongested using oxymetazoline soaked cotton pledgets for 5 minutes, allowing for adequate decongestion and vasoconstriction. A malleable retractor is used to depress the tongue to provide a clear view of the oropharynx and access to the nasopharynx. McCrea urethral dilators of increasing size are passed 30-35 mm beyond the nasal mucocutaneous junction to perforate the atretic plate along its thinnest portion. It is imperative that this is done under direct visualization with either a 120° 2.4 mm endoscope or an indirect mirror examining the posterior aspect of the atretic plate to ascertain that the dilators are passing into the correct position. If the atretic plate is thick, other ancillary methods (ie, backbiting forceps, microsurgical débriders, and guarded drills) may be required to remove choanal soft tissue and bone under direct visualization. Unfortunately, simple transnasal puncture has a high rate of restenosis; in one series by Hengerer et al,
50% of infants had evidence of restenosis after transnasal puncture, requiring additional surgical procedures to address persistent symptoms. As a result, transnasal puncture should be combined with other techniques including Endoscopic Resection and Intraoperative Adjuncts to minimize risk of restenosis.
Endoscopic resection
First pioneered by Stankiewicz in the 1990s, many variations of endoscopic resection have been published in the literature.
Initially, endoscopic approaches were chiefly used in older children with unilateral CCA. However, with advancements in technological equipment and surgical technique, several groups have published successful endoscopic repair in symptomatic neonates as early as the first few days of life. Compared to transnasal puncture, the endoscopic approach is technically more difficult to perform due to the small size of the neonatal nose. However, this approach provides superior visualization of the atretic plate and the surrounding intranasal anatomy, allowing for accurate removal of obstructing soft tissue and bone. After endotracheal intubation, the intranasal cavities are first suctioned free of secretions and decongested using oxymetazoline soaked cotton pledgets for 5 minutes, allowing for adequate vasoconstriction. The posterior tip of the middle turbinate is a useful anatomical landmark; remaining inferior to this structure minimizes risk of intracranial injury. A 0° 2.4 mm endoscope is used to visualize the atretic plate. Mucosal flaps are elevated, paying attention to exposure of the posterior septum. The plate is then perforated under direct visualization. It is often found to be dehiscent in one area or thin enough that this can be done with a suction. After passage into the postnasal space, the opening is enlarged, typically by removing the posterior part of the septum with either backbiting forceps, microsurgical débriders, or guarded drills (Figure 2). Raised flaps are tiny and may be damaged during this part of the procedure but it has not been proven that preserving mucosal flaps prevents restenosis. Recently, repeated balloon dilation has also been used successfully to treat CCA. As patients with CCA often have an area of opening within the bone, a sinuplasty balloon may be placed through this soft membranous portion to dilate the neochoanae. Outcomes utilizing the endoscopic endonasal approach, with or without postoperative stenting, are quite good, with a revision rate ranging in the literature from 0%-38%.
in 2000, only 3% of respondents, members of the American Society of Pediatric Otolaryngology, did not routinely use stents in CCA repair. Since then, practice patterns have shifted in decreasing the duration of stenting or avoiding the use of stenting altogether. Despite this, it remains advisable to place stents in children who are at a high risk of failure: this includes neonates and bilateral CCA with a thick atretic plate.
Stenting ensures that the nasal airway is open in the early postoperative period. In neonates, the stent is typically a size 3.0 or 3.5 mm endotracheal tube. This tube is folded in half and a posterior fenestration is cut (Figure 3). The fenestrated, folded-end straddles the vomer; an indirect mirror examination of the nasopharynx ensures precise positioning of the stent. The stent is placed in a similar fashion to a posterior nasal pack. A small catheter is placed into each nasal cavity, advanced, and brought out through the oral cavity. The open ends of the stent are sutured to these catheters. Care must be taken to ensure any curve present in the stent is positioned such that pressure on the nasal alae is minimized. The stent is fed in through the mouth while the catheters are pulled out through the nose. Once the open ends of the stent emerge from the nose anteriorly, the catheters are removed and the stents are trimmed. The stents need to be long enough to allow some growth, but short enough such that they do not interfere with routine feeding. A bead the approximate width of the columella is cut from the same endotracheal tube and placed between the stents. Then a suture is run from one stent, through the bead, through the second stent, and back, tied adjacent to the bead so the knot can be pushed into it. This minimizes the risk of pressure necrosis on the child′s nose. To minimize the risk of restenosis, the stents are left in place for at least 2-6 weeks postoperatively.
Figure 3Stent placement. The stent is made from an endotracheal tube. (A) A hole is cut in the middle of the endotracheal tube. This will eventually sit in the patient’s nasopharynx and allow nasal breathing. (B) The stent is placed in the same way a posterior nasal pack is placed. Catheters are passed through each nasal cavity and brought out through the mouth. Each catheter is sutured securely to one end of the stent. The catheters with the stent attached are withdrawn from the nose, carrying the stent through the nasal cavity. Keeping the catheters on the same side they were placed is important; they should not cross during stent placement. Endotracheal tubes are slightly curved, and the curve present in the stent should be positioned such that pressure on the nasal structures is minimized. (C) The external ends of the stent are joined by passing a suture between them. A piece of the endotracheal tube is cut into a bead that is placed between the stents to keep them separated. The stents are trimmed such that oral feeding is possible. The bead is placed as far from the columella as possible. Stents should be somewhat mobile, they can be pushed in to allow feeding and pulled out to allow suctioning. (D) Final appearance of the stents.
Laser repair of CCA has been in use by otolaryngologists for over 30 years. It has allowed for precise dissection and hemostatic ablation in the setting of a small neonatal nose. Contact diode (CDL), potassium-titanyl-phosphate (KTP), and neodymium: yttrium–aluminum–garnet (Nd-YAG) beams have all been described in the successful management of CCA. Specifically, innovative utilization of both CDL and KTP lasers has resulted in simultaneous visualization and tissue vaporization during CCA repair. CDL allows for precise ablation via “near field” delivery of laser light, with minimal risk to structures beyond the proposed target as 90% of the laser′s energy is dissipated due to beam divergence, within 1 mm from the tip. Hemostasis is achieved due to the high hemoglobin absorbance at 810 nm. The small 0.6 mm diameter of the KTP fiber optic laser, delivered through a narrow handpiece, enables simultaneous insertion of a 0° 2.4 mm endoscope armed with a smoke evacuator, allowing for excellent telescopic control and convenience of fiber delivery with precise hemostatic ablation of the visualized atretic plate. Early outcomes regarding KTP resection are promising; Tzifa et al
report no instances of restenosis at 1 year following definitive surgical resection. However, as with all powered instruments, significant morality has been reported due to air embolus formation after intranasal use of Nd-YAG, warranting stringent attention with appropriate laser precautions intraoperatively.
Mitomycin C, an aminoglycoside antibiotic isolated from Streptomyces caespitosus, is an antiproliferative agent designed to inhibit fibroblastic growth and proliferation. Its use to prevent granulation and subsequent scar formation in various ophthalmologic and otolaryngologic procedures led to similar topical application during CCA repair. If utilized, a concentration of 0.4 mg/mL is placed on a cotton pledget along the neochoanae for approximately 2-4 minutes. After initial enthusiasm, several case series have shown no convincing benefit of mitomycin C on long-term success rates. More recent reports suggest topical Mitomycin C may result in less granulation tissue formation, lower rates of restenosis, and fewer revision surgeries.
Nevertheless, long-term safety concerns exist with the use of a potentially oncogenic medication for a relatively benign neonatal condition. Currently, there is not enough evidence to support routine use of mitomycin C in CCA repair.
Surgical complications
Although rare, intraoperative complications include epistaxis and injuries to the nasal subunits, orbit, skull base (ie, cerebrospinal fluid leak and meningitis), central nervous system, and torus tubarius. However, the advent of triplanar image guidance systems has further optimized surgical efficiency and significantly increased the safety of the procedure, particularly in cases with skull base abnormalities. Many of the early complications seen in CCA repair are related to stent placement, which includes alar or columellar necrosis, intranasal infection, nasal discomfort, premature extrusion, septal perforation, stent migration, stent occlusion, and synechiae formation.
The most common late complication is restenosis of the neochoanae. This may be caused by excessive tissue trauma during surgical dissection, inadequate bone removal from the choanal-septal edge, and excess cicatrix deposition around the border of the neochoanae. Recurrences can occur between 2 months to 6 years postoperatively and are typically managed with choanal dilation, sometimes with division of the encircling scar band with a sharp sickle blade. The lowest recurrence rates are seen in older children (ie, unilateral CCA) and patients with nonsyndromic CCA.
Postoperative care
After definite surgical repair, neonates should be closely observed overnight with continuous pulse oximetry for signs of acute upper airway obstruction. If intranasal stents are placed, they should be irrigated with saline drops and suctioned regularly. The length of the stents should be clearly noted intraoperatively to facilitate accurate intranasal suctioning. In parallel, any signs of gastroesophageal reflux should similarly be treated using an H2-receptor antagonist or equivalent to minimize granulation tissue formation. Neonates are typically followed at intervals of 2-4 weeks until complete resolution of symptoms is observed.
Stent removal requires a short general anesthetic. The mouth is opened with a small sweetheart or malleable retractor. Any sutures holding the stents together anteriorly are cut and removed. The stents are then pushed back through the nose. Once the stent is seen in the oropharynx, it is grasped with a pair of forceps and withdrawn through the oral cavity. Nasal endoscopy should be done at this point to debride any granulation tissue and evaluate for synechiae formation or other intranasal sequelae of stenting that should be corrected. Our practice is to follow stent removal with a 2-week course of a combined topical antibiotic and steroid drop to reduce granulation and restenosis.
Conclusion
Bilateral choanal atresia is a congenital nasal anomaly which requires expeditious repair before a neonate can feed orally and breathe adequately. With appropriately sized endoscopic instruments, transnasal repair can be efficient and effective. Favorable results with or without stenting are typical. More research into ancillary procedures such as topical treatments and stenting have the potential to improve existing tools in our armamentarium.
Disclosures
The authors report no proprietary or commercial interest in any product mentioned or concept discussed in this article.
References
Flake C.G.
Ferguson C.F.
Congenital choanal atresia in infants and children.
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