Choanal Atresia

Choanal Atresia

Nathan S. Alexander, MD, and James W. Schroeder, Jr, MD, FACS, FAAP

Introduction/Etiology/Epidemiology

•Choanal atresia is a relatively rare congenital craniofacial defect characterized by the obstruction of the posterior nasal passages.

•The incidence rate has been noted to range between 1 in 5,000 and 1 in 10,000 live births. Although it had long been thought that a 2:1 ratio favored both female to male patients and unilateral to bilateral cases, extensive literature reviews have shown that the ratio is closer to 1:1 for both relationships.

•Unilateral cases are likely to be isolated (unrelated to other congenital anomalies); bilateral cases are likely to be associated with specific disorders or multiple congenital anomalies (98%).

Pathogenesis

•The pathogenesis of choanal atresia is not fully understood.

•The most widely accepted theory is that affected individuals have either an abnormal persistence of the buccopharyngeal membrane from the foregut or persistence of the nasobuccal membrane of Hochstetter, which typically resorbs around the sixth week of gestation.

Clinical Features

•Neonates are classically thought to be obligate nose breathers, though some newborns are better able to switch to mouth breathing when required.

—By 4–6 weeks of life, almost all infants are able to manage mouth breathing well.

•As such, presentation of choanal atresia can look very different between bilateral and unilateral atresia, given the degree of airway obstruction.

—Bilateral choanal atresia is often diagnosed soon after birth and appears with complete nasal obstruction, which manifests with apnea and results in decreased oxygen saturation, which is subsequently relieved by crying (cyclic cyanosis). This can represent a medical emergency. Feeding difficulty can also be the alerting event, where a newborn’s suck-swallow-breathe reflex is severely impaired by the bilateral nasal obstruction.

—Unilateral choanal atresia may present later in infancy. These patients typically do not present with neonatal respiratory distress but instead present later in life (usually at 5–24 months of age, sometimes closer to 5 years of age, and rarely in adulthood). The most common presentation in these patients is chronic unilateral nasal obstruction, persistent rhinorrhea, or chronic sinusitis.

Differential Diagnosis

•Rhinitis—viral, bacterial

•Deviated nasal septum (may be from birth trauma)

•Nasal foreign body

•Nasal turbinate hypertrophy

•Pyriform aperture stenosis (congenital narrowing of the anterior nasal cavity)

•Adenoid hypertrophy (unlikely in a neonate)

Diagnostic Considerations

•Diagnosis is determined in a stepwise fashion.

•First, physical examination is performed specifically to look for fogging of a mirror or a cold speculum held under the nare during exhalation. Movement of a cotton wisp under the nare may also be helpful.

•Second, passage of a 5-F to 8-F flexible suction catheter through the nose may help establish patency of the nasal passage.

—Resistance within 1–2 cm of the alar rim may imply misdirection toward the superior nasal cavity or deflection from the turbinate(s) or piriform aperture stenosis.

—Resistance at 32–35 mm indicates an issue with potential obstruction at the level of the choana.

•Third, referral to a pediatric otolaryngologist for flexible nasal endoscopy after mucosal decongestion is necessary to visualize the actual point of resistance and establish the diagnosis.

•Finally, unenhanced computed tomography of the facial bones and sinuses with 2–5-mm sections is performed with proper prescanning preparation of the nasal cavity (to include decongestion of the nasal mucosa and suctioning of the nasal secretions). The scan should be ordered in consultation with a pediatric otolaryngologist to ensure that the proper study and timing are scheduled to prevent unnecessary radiation exposure. This facilitates assessment of the thickness of the atresia plate and the degree of lateral pterygoid plate and medial vomerine involvement, as well as planning for surgical intervention (Figure 10-1).

Figure 10-1. Choanal atresia in a 1-day-old female neonate with difficulty breathing. Axial computed tomographic bone window images show narrowing of the right nasal canal (arrows).

Management

•In the case of a neonate with bilateral choanal atresia in respiratory distress, initial treatment includes placement of an oral airway, a McGovern nipple (a standard nipple with an enlarged hole, secured with a tracheostomy tie), or oral intubation.

•Nutritional support can be provided with an orogastric feeding tube placed alongside the McGovern nipple or oral airway.

Surgical Repair

Transnasal Puncture

•The classic technique involves using a curved trocar while protecting the skull base with a finger in the mouth. Progressively larger dilators then enlarge the opening.

•This method has fallen out of favor for its high restenosis rate, inability to visualize the surgical field, and inability to allow resection of the posterior vomer.

•This technique has been refined to improve visualization by using laryngeal mirrors and nasal endoscopes (Figure 10-2). More recently, balloon dilation has been used for initial dilations, as well as revisions.

•The transnasal puncture technique is not recommended for a thick bony atretic plate or patients with CHARGE syndrome (coloboma of the eye, heart anomaly, choanal atresia, retardation, and genital and ear anomalies).

Figure 10-2. The right choanal atresia plate is demonstrated after endoscopic transnasal puncture, prior to dilation. AP = atretic plate, IT = inferior turbinate, MT = middle turbinate, S = septum.

Transpalatal Repair

•Transpalatal repair (Figure 10-3) involves a U-shaped mucosal incision along the alveolar arch. A mucosal flap is developed on the basis of the greater palatine vessels. The atresia plates are drilled by using a diamond burr.

•Despite success rates of approximately 84%, this technique has fallen out of favor, given its increased risk of impairment of palatal growth, which can subsequently lead to maxillary development abnormality and cross-bite (52% risk). Palatal fistula, postoperative pain, and flap breakdown are more serious potential complications from the procedure.

Transnasal Endoscopic Repair

•Transnasal endoscopic repair has become the primary and preferred surgery for the repair of choanal atresia by most pediatric otolaryngologists.

•This technique involves the use of a Hopkins rod telescope placed through the nasal cavity to evaluate the atretic plate. A 120° Hopkins rod-lens telescope is placed transorally to view the choana from the nasopharynx. This allows for the controlled puncture of the atretic plate under direct vision endoscopically. Once this controlled puncture is performed, that aperture within the atretic plate can be enlarged with urethral sounds and/or balloons. Use of a backbiter nasal punch, microdebrider, curette, and drill may also be used.

Figure 10-3. Endoscopic images of right choanal atresia repair. A. The mucosal flap has been elevated on the lateral wall to create space for the drill-out of the vomer and lateral nasal wall. B. The flap has been laid in position. C. Postoperative image obtained 1 month after the procedure.

Controversies

•Postoperative stent placement: After the creation of a patent choana, there has long been the theory that to reduce the risk of restenosis, a postoperative stent should be placed. However, some surgeons will opt not to place a postoperative stent. Most surgeons will require those who have undergone choanal atresia repair to return for postoperative debridement and dilation either in the office or in the operating room with anesthesia.

•Mitomycin C: An antitumor aminoglycoside antibiotic, mitomycin C inhibits fibroblast proliferation and migration. Topical application has shown some improvement in outcomes after choanal atresia repair.

Treating Associated Conditions

•Associated congenital anomalies are seen in 50%–70% of cases of choanal atresia.

•The most commonly seen associated abnormalities are those that occur with CHARGE syndrome (Box 10-1).

•Given the prevalence and association with CHARGE syndrome, consultations with personnel from ophthalmology, cardiology, neurology, nephrology, otolaryngology, and genetics are appropriate. In children who present with the defects of CHARGE syndrome, 50% will have some form of choanal atresia.

Expected Outcomes/Prognosis

•Surgical success in repairing choanal atresia is dependent on the technique used.

•Transnasal endoscopic repair is reported to have a success rate of approximately 85%.

•Children with bilateral atresia (who often undergo surgery early in life), CHARGE syndrome, or other craniofacial abnormalities may require multiple surgeries to decrease restenosis.

Box 10-1. Diagnostic Criteria for CHARGE Syndrome