Choanal Atresia

In 1755, Roederer first described congenital choanal atresia; therefore, this condition has been recognized for more than 200 years. In 1854, Emmert reported the first successful surgical procedure for congenital choanal atresia in a 7-year-old boy using a curved trocar transnasally. Over the years, the necessity of serial dilatations to maintain patency of the choanae has been clearly recognized.

Frequency

The average rate of choanal atresia is 0.82 cases per 10,000 individuals. Unilateral atresia occurs more frequently on the right side. The ratio of unilateral to bilateral cases is 2:1. A slightly increased risk exists in twins. Maternal age or parity does not increase the frequency of occurrence. Chromosomal anomalies are found in 6% of infants with choanal atresia. Five percent of patients have monogenic syndromes or conditions.

Race

Choanal atresia occurs with equal frequency in people of all races.

Sex

Studies report significantly more females than males affected by choanal atresia. A report by Michalski et al, using data from the National Birth Defects Prevention Study (1997-2009), indicated that the female-to-male ratio for infants with choanal atresia is 2.2.[5]

The nasal cavities extend posteriorly during development under the influence of the posteriorly directed fusion of the palatal processes. Thinning of the membrane occurs, which separates the nasal cavities from the oral cavity. By the 38th day of development, the 2-layer membrane consisting of nasal and oral epithelia ruptures and forms the choanae (posterior nares). Failure of this rupture results in choanal atresia. Although these choanae are not in the same location as the definitive choanae, which are eventually located more posteriorly, the unexpectedly anterior extent of choanal atresia is explained.[1]

In 2008, Barbero et al suggested that prenatal use of antithyroid (methimazole, carbimazole) medications was linked to choanal atresia.[6]

Lee et al (2012) evaluated the association between continuous and categorical infant T4 levels and nonsyndromic choanal atresia.[7] They suggest a role of low thyroid hormone levels in the development of choanal atresia, or that low newborn T4 levels are potential proxy measures of a risk factor present during the critical period of development.

Using data published data from the National Birth Defects Prevention Study, Kancherla et al (2014) found evidence linking choanal atresia to maternal exposure to various nutrients, thyroid medications, and cigarettes. The investigators looked at prepregnancy exposures (within 1 year prior to conception) and periconceptual exposure (between 1 month before and 3 months after conception) in 117 women who gave birth to infants with choanal atresia and 8350 control mothers. Positive associations were found between the following prepregnancy exposures and choanal atresia[8] :

• Intake in the highest quartile: Vitamin B-12, zinc, niacin

• Intake in the lowest quartile: Methionine, vitamin D

• Coffee (≥ 3 cups per day)

Positive associations were also found between the following periconceptual exposures and choanal atresia:

• Thyroid medications

• Cigarette smoking

A number of theories have been proposed to explain the occurrence of choanal atresia, and they can be summarized as follows:

• 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

The clinical evaluation includes a complete physical examination to assess for other congenital anomalies. A small feeding tube could be used to determine the patency of the choana, but a complete nasal and nasopharyngeal examination should be performed using a flexible fiberoptic endoscope to assess the deformity. A simple method using the automatic tympanometer to screen newborns for congenital choanal atresia was recently published. The sensitivity and specificity of the technique in diagnosing a patent nostril was reported as 100%. However, a high level of suspicion is required to diagnose bilateral choanal atresia.

Symptoms of severe airway obstruction and cyclical cyanosis are the classic signs of neonatal bilateral atresia. When crying alleviates respiratory distress in an obligate nasal breather, the neonatologist should be alerted to the probability of bilateral choanal atresia. Unilateral atresia may not be detected for years, and patients may present with unilateral rhinorrhea or congestion.

Many patients have an associated narrowed nasopharynx, widened vomer, medialized lateral nasal wall, and/or arched hard palate. Associated malformations occur in 47% of infants without chromosome anomalies. Nonrandom association of malformations can be demonstrated using the CHARGE association, which appears to be overused in clinical practice. The components of the CHARGE association are as follows:

• Coloboma of the iris, choroid, and/or microphthalmia

• Heart defect such as atrial septal defect (ASD) and/or conotruncal lesion

• Atresia of choanae

• Retarded growth and development

• Genitourinary abnormalities such as cryptorchidism, microphallus, and/or hydronephrosis

• Ear defects with associated deafness (The external, middle, and/or inner ear may be involved. Only a small proportion of infants with choanal atresia and related components probably represent this entity.)

The percentages of the different anomalies in CHARGE association are as follows:

• Coloboma - 80%

• Heart defect - 58%

• Atresia of choanae - 100%

• Mental retardation - 94%

• Growth deficiency - 87%

• Genital hypoplasia in males - 75%

• Ear anomalies - 88%

Differential diagnosis

Deviated nasal septum

Dislocated nasal septum

Septal hematoma

Mucosal swelling

Turbinate hypertrophy

Encephalocele

Nasal dermoid

Hamartoma

Chordoma

Teratoma

Rhinography is a procedure that involves the administration of radiopaque dye into the nasal cavity as illustrated in the image below.

CT scanning is the radiographic procedure of choice in the evaluation of choanal atresia. For good results, careful suctioning is performed to clear excess mucus, and a topical decongestant is applied. The purpose of CT scanning is outlined as follows:

• Confirm the diagnosis of choanal atresia (unilateral or bilateral).

• Evaluate choanal atresia (vomer bone width and choanal airspace distance).

• Exclude other possible nasal sites of obstruction.

• Determine the degree of bony, membranous, or mixed atresia.

• Delineate abnormalities in the nasal cavity and nasopharynx.

CT scan image of choanal atresia is seen below.

See the list below:

• Failure to pass an 8F catheter through the nasal cavity more than 5.5 cm from the alar rim

• The lack of movement of a thin wisp of cotton under the nostrils while the mouth is closed

• The absence of fog on a mirror when it is placed under the nostrils

• Acoustic rhinometry

• Listening for breath sounds with either a stethoscope or a Toynbee auscultation tube

• Gently blowing air into each nasal cavity with a Politzer bag

• Administering into the nose a colored solution that is visible in the pharynx

Treatment can be divided into emergent and elective definitive categories. Bilateral choanal atresia in a neonate is an emergency that is best initially treated by inserting an oral airway to break the seal formed by the tongue against the palate. This oral airway can be well tolerated for several weeks. The method of repair is controversial, with no technique having gained universal acceptance. Bilateral choanal atresia in the newborn requires prompt diagnosis and airway stabilization. An oral airway, McGovern nipple, and intubation are viable options. The ideal procedure for choanal atresia restores the normal nasal passage, prevents damage to growing structures important in facial development, is technically safe, requires short operative time, and provides short hospitalization and convalescence.[1]

Procedures

Transnasal puncture, with or without a microscope, became unpopular because of the high rate of failure that then required revision. This was attributed to the difficulty in visualizing the choanal area that required special surgical attention, such as the vomerine septal bridge and bony narrowing of the lateral walls. The transnasal approach becomes more difficult in the presence of septal deviation, turbinate hypertrophy, nasal discharge, and elongation of the depth from the nasal vestibule to the posterior choanae as patients grow.

The transseptal technique consists of making a window in the septum anterior to the atretic plate.

Transpalatal repair, as seen in the image below, is a technique that provides excellent exposure and has a high success rate but requires more operative time. The increased blood loss and the possible occurrence of palatal fistula, palatal dysfunction, and maxillofacial growth disturbance are complications of this procedure.

The endoscopic technique (nasal or retropalatal), with or without powered instrumentation, offers excellent visualization with great ease in removing the bony choanae.[3] The potential of certain instruments for the management of choanal atresia was published, such as the retrograde 110° Sekunda endoscope and silicone horseshoe-shaped protectors.[9]

A retrospective study by Karligkiotis et al indicated that congenital choanal atresia can be safely and effectively treated through an endoscopic endonasal surgical approach. The study, which included 84 patients, found the success rates for unilateral and bilateral choanal atresia to be 96.3% and 86.2%, respectively.[10]  Combined transoral-transnasal is another technique that provides a good alternative for managing choanal atresia, with easier, four-handed surgery to ensure adequate posterior choana for nasal breathing.[4]

Microdebriders continue to advance the field of endoscopic surgery, providing clearer operative fields and causing less tissue trauma for experienced surgeons. However, the severity of complications, including the potential for rapidly aspirating orbital and cerebral contents when laminae are violated, must be appreciated and respected.

Carbon dioxide and potassium titanyl phosphate (KTP) lasers are easy and quick and create minimal discomfort for the patient. The time of hospitalization is short, and the operation can be repeated if a good result is not initially achieved. Most importantly, a stent is not usually needed. The use of mitomycin C topically as an adjunct to the surgical repair of choanal atresia may offer improved patency with a decreased need for stenting, dilatations, and revision surgery.[11]  In the transnasal approach discussed by Karligkiotis et al, vomer removal and the employment of mucoperiosteal flaps were reported as the main elements for reducing the incidence of postoperative stenosis; as a result, neither stenting nor the use of mitomycin C was considered to be mandatory.[10]

Infants with documented gastroesophageal reflux disease (GERD) require prolonged stenting and dilatations for choanal restenosis and removal of granulation tissue. Stenting is usually performed using an endotracheal tube or Foley catheter. The advantages of Foley catheter stenting for choanal atresia are as follows:

• Well tolerated by the patient

• Simple to introduce, fix, and remove

• Minimizes septal or columellar necrosis

• Minimizes nasal cavity and paranasal sinus infections

• Adjustable with inflation or deflation of the balloon that controls the pressure on the choanal walls

• Easy to fix in cases of unilateral atresia

The use of stents in the treatment of patients with choanal atresia is a controversial subject. Some surgeons believe that stents are useful in stabilizing the nasal airway in the postoperative period to prevent the development of stenosis by maintaining a lumen. However, others believe that stents may act as a nidus for infection and may induce a foreign body reaction. This may contribute to choanal restenosis, much as an endotracheal tube may cause subglottic stenosis. Therefore, the use of stents following repair of choanal atresia requires the use of prophylactic antibiotic and antireflux medications.

A retrospective review by Carter et al (2014) involving 17 pediatric patients who underwent endoscopic choanal atresia repair (37 total operations) found stenting to be associated with the need for a significantly greater number of procedures, increased granulation tissue formation, and significantly longer hospitalization. Nonetheless, the investigators recommended that stent placement be considered after surgery in all neonates in order to prevent postoperative airway obstruction.[12]

Cedin et al (2006) analyzed the long-term results of a new stentless surgical technique for choanal atresia.[13] They reported that, using neither stents or nasal packing, this technique allowed fast recovery in a one-step surgery.

Newman et al (2013) analyzed different factors affecting 15-year surgical outcomes of choanal atresia repair.[14] They found that their revision rate after initial endoscopic repair of choanal atresia was low and was unaffected by adjuvant mitomycin C therapy or stenting.

In contrast, in the aforementioned study by Carter et al, the investigators found topical mitomycin to be an efficacious adjuvant therapy in endoscopic choanal atresia repair, having been associated with reductions in the formation of granulation tissue, rate of restenosis, and number of surgeries.[12]

In a study of pediatric patients with choanal atresia, Attya et al found that the restenosis rate was greater in patients with the bilateral form of the condition or with comorbidities, such as GERD. The mean number of operations among patients with bilateral choanal atresia was 5.24, compared with 2.2 for those with the unilateral type.[15]

Following surgical repair of choanal atresia, patients may require operative debridement or periodic dilatations. Periodic dilations can sometimes be performed as an outpatient procedure with local decongestant and topical anesthesia using urethral sounds.

Bedwell et al (2011) described the use of balloon dilation to repair choanal atresia in a series of patients with membranous stenoses, postrepair granulation, and scar tissue in revision cases.[16] They concluded that balloon dilation is an effective adjuvant tool for use in the repair of choanal atresia and stenosis.

In August 2019, the International Pediatric Otolaryngology Group (IPOG) published consensus recommendations, including the following, with regard to pediatric choanal atresia diagnosis and care[17] :

• Nasal endoscopy or fiberscopy and computed tomography (CT) scanning are recommended diagnostic modalities
• Whenever possible, unilateral choanal atresia repair should wait until the patient is over age 6 months
• Treatment with transnasal endoscopic repair is preferred
• Patient follow-up for at least 1 year, via nasofiberscopy or rigid endoscopy (but without systematic imaging), is recommended