Choanal atresia

WikiDoc Resources for Choanal atresia
Articles
Most recent articles on Choanal atresia Most cited articles on Choanal atresia Review articles on Choanal atresia Articles on Choanal atresia in N Eng J Med, Lancet, BMJ
Media
Powerpoint slides on Choanal atresia Images of Choanal atresia Photos of Choanal atresia Podcasts & MP3s on Choanal atresia Videos on Choanal atresia
Evidence Based Medicine
Cochrane Collaboration on Choanal atresia Bandolier on Choanal atresia TRIP on Choanal atresia
Clinical Trials
Ongoing Trials on Choanal atresia at Clinical Trials.gov Trial results on Choanal atresia Clinical Trials on Choanal atresia at Google
Guidelines / Policies / Govt
US National Guidelines Clearinghouse on Choanal atresia NICE Guidance on Choanal atresia NHS PRODIGY Guidance FDA on Choanal atresia CDC on Choanal atresia
Books
Books on Choanal atresia
News
Choanal atresia in the news Be alerted to news on Choanal atresia News trends on Choanal atresia
Commentary
Blogs on Choanal atresia
Definitions
Definitions of Choanal atresia
Patient Resources / Community
Patient resources on Choanal atresia Discussion groups on Choanal atresia Patient Handouts on Choanal atresia Directions to Hospitals Treating Choanal atresia Risk calculators and risk factors for Choanal atresia
Healthcare Provider Resources
Symptoms of Choanal atresia Causes & Risk Factors for Choanal atresia Diagnostic studies for Choanal atresia Treatment of Choanal atresia
Continuing Medical Education (CME)
CME Programs on Choanal atresia
International
Choanal atresia en Espanol Choanal atresia en Francais
Business
Choanal atresia in the Marketplace Patents on Choanal atresia
Experimental / Informatics
List of terms related to Choanal atresia

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Jaspinder Kaur, MBBS[2]

Synonyms and keywords: Atresia, Choanal; Atresias, Choanal; Choanal Atresias; Bosma arhinia microphthalmia syndrome; Bosma Henkin Christiansen syndrome; Congenital absence of nose and anterior nasopharynx

Overview

The word “Choana” is derivative of a greek word “Xovan” which states the funnel and hence, the term “Posterior Choana” is known as posterior nasal aperture or posterior funnel. Choanal atresia (CA) is the most common form of congenital nasal airway abnormality which presents with variable clinical features ranging from acute airway obstruction to chronic recurrent sinusitis depending upon the degree of obstruction. It is caused by the abnormal rupturing of the buccopharyngeal or naso-buccal membrane which results in the failed recanalization of the nasal fossae during the embryological period and hence, occlude the posterior nasal cavity to communicate with the nasopharynx. CA presents with severe respiratory distress, difficulty feeding, and failure to thrive when the obstruction is bilateral; and chronic persistent nasal discharge in unilateral cases. Establishing an airway is an acute otolaryngological emergency because newborns are obligate nasal breathers and experiences the paradoxical cyanosis episodes while feeding. The diagnosis requires a high index of suspicion and usually initial clinical evaluation done by introduction of a six or eight Fr suction catheter via the nostrils, methylene blue dye test, cotton wisp test, and laryngeal mirror test. The obstruction may be further visualized with a narrow flexible nasopharyngoscope after the nasal cavity has been suctioned of mucus and the nasal mucosa has been constricted with a nasal decongestant (e.g., oxymetazoline). However, the final confirmation of the diagnosis is done by CT scan of the nasal cavity which will demonstrate the atresia, define the type of tissue (bony or membranous), and show the configuration of the entire nasal cavity. The treatment of choanal atresia is essentially surgical which can be divided into emergent and elective definitive categories. It may be successfully treated by removing the obstructing tissue by using the nasal endoscopic approach via transnasal route. However, when the thick bony plate extremely narrows posterior nasal cavity, a transpalatal repair technique is more direct. An intraoperative topical application of mitomycin to inhibit fibroblast proliferation has shown to be an effective adjunct to the surgical repair of choanal atresia. Stents fashioned from endotracheal tubes are placed and secured alongwith sutures to the septum in order to prevent postoperative re-stenosis chances which are removed after 6 weeks of duration. The stents must be moistened with saline and suctioned several times daily to prevent mucus plugging and acute respiratory distress.

Historical Perspective

• 1755: Johann Roderer noticed total obstruction of the posterior nasal choana while examining a newborn and hence was the first to describe the CA.
• 1829: Oto et al. further characterized the CA anomalies in relation to the deformity of the palatine bones during an autopsy.
• 1854: Carl Emmert was the first to use the curved trochar through the choanal obstruction in transnasal surgical repair of bilateral CA in a 7- year-old boy and thus, successfully corrected CA surgically.
• 1880: Ronaldson described an importance of CA in his autopsy findings of the newborns who had died from asphyxia and acute respiratory distress.
• 1979: Hall first reports the “CHARGE” syndrome association in 17 children with multiple congenital anomalies who were ascertained by CA. In the same year, Hittner et al found the same syndrome in 10 children with ocular colobomas and multiple congenital anomalies, hence coined the syndrome as “Hall-Hittner syndrome”.
• 1981: Pagon et al. first elaborated the acronym "CHARGE" association.
• 1985: Dehaen conducted the first transnasal endoscopic repair of CA.
• 2008: Barbero et al found the association of CA with the maternal use of an antithyroid drug methimazole.

Classification

CA can be classified on the basis of several variables such as morphology, laterality, association with congenital anomalies and surrounding structures involvement as described in the following tables from Table 1 to 4.

Table 1: Based on the morphology

Type of morphology	Past report (1910)	Recent data based on CT and histologic specimens (1996)
Membranous	10%	0%
Bony	90%	30%
Mixed membranous and bony atresia	0%	70%

Table 2: Based on the laterality

Characteristics features	Unilateral	Bilateral
Type of obstruction	Partial or one nasal passage blocked	Total or both nasal passages blocked
Incidence	70%	30%
Side: Right or left	Right (70%)	Both
Severity	Carries low morbidity	Life threatening
Onset of symptoms	Immediately after birth	Appears later in childhood or adulthood

Table 3: Based on association with other congenital anomalies

Characteristics features	Associated with other anomalies	No associations
Incidence	50%	50%
Type of CA	Bilateral CA	Unilateral CA
Syndromes associated	CHARGE syndrome, 9p monosomy, Crouzon syndrome, Marshall-Smith syndrome	None

Table 4: Based on structure involvement

Characteristics features	Membranous	Bony
Surrounding structural abnormalities	Failure of the bucconasal membrane to rupture between the 5th and 6th weeks of fetal development.	Medial thickening of the medial pterygoid plates; Lateral thickening of the posterior vomer; Narrow nasal cavity

Embryology

Origin: Development of the nasal cavity begins with neural crest cells migration from their origin in the dorsal neural folds. The development of posterior choanae takes place between the 4th and 11th weeks of gestation which is elaborated in Table 5.

Table 5 explains the embryological process for the development of posterior choanae:

Gestational week	Developmental process
3rd and 4th week	Neural crest cells commence their caudal migration to reach the midface by the 4th week of gestation. The nasal processes or placodes on the lateral surface of head invaginate to form the nasal pits.
5th week	The nasal pits begin to fold inwards into the mesenchyme forming the nasal sacs. These primitive nasal sacs are separated from oral cavity by an oronasal membrane.
8th week	The oronasal membrane ruptures creating nasal cavity, and a primitive choanae located at the junction of nasal cavities and nasopharynx. During this phase of development, there is gradual proliferation of neural crest cells which further contribute to the formation of skull base and nasal vaults. The lateral palatal shelves fuse in an anterior-to-posterior direction which subsequently forms the hard and soft palate.
10th week	The nasal septum and developing palate fuse. The primitive choanae gets pushed posteriorly to form “Secondary choanae”. In normal fetus, these secondary choanae are patent for a functional airway between the anterior nasal cavity and nasopharynx.

• Normal anatomical relations of the atretic plate are as follows:

1. Superior surface: Under surface of body of sphenoid
2. Lateral border: Medial pterygoid lamina
3. Medial border: Vomer
4. Inferior surface: Horizontal plate of palatine bone

Pathophysiology

• Obligate nose breathers: In neonates, the epiglottis is more superiorly placed in relation to adults so when infant swallows, the larynx rises above epiglottis position and touch the nasopharynx, and locks between soft palate and sides of nasopharynx. Due to this elevated laryngeal position compared to the adults, newborns are obligate nose breathers until mouth breathing is established with the subsequent descent of the larynx at approximately 4–6 weeks of life.
• During inspiration, the neonate sucks the tongue and creates the vacuum in the oropharynx which moves soft tissue of the floor of mouth up and back towards soft palate.
• During expiration, the airways pressure causes soft palate to push forward against the soft tissue and tongue in the mouth and further obstructs the oral airway.
• Interrelation of respiration, feeding and crying episodes:
  • As the infants are obligate nasal breather, the oral airway is used by them only during crying; otherwise it is invariably blocked or used by them during normal respiration.
  • The 1/3rd reduction in the diameter of the nasal airway increase nasal airway resistance by 81 times resulting in severe distress in neonates. As a result, the infant with bilateral CA experiences episodes of asphyxia and severe distress in quiet respiration when their mouth is normally closed, especially during sleep or feeding times.
  • Feeding difficulty can be the initial presenting event in which the infants can present with progressive airway obstruction and choke episodes while feeding because of their inability to breathe and feed at the same time.
  • Moreover, the infant can become cyanotic which is relieved by crying or gasping as the child opens the mouth widely, releases the air obstruction and subsequently, the cyanosis disappears. However, the cycle repeats itself if the crying stops and the mouth closes.
  • Similarly, as the child falls asleep, the mouth closes and a progressive obstruction starts with stridor followed by increased respiratory effort and cyanosis. Either the observer opens the child's mouth or the child cries and the obstruction is cleared.
  • In resting state, child has severe retractions, and struggles to breath with rapid cyclic development of cyanosis. Moreover, the infant with bilateral CA rarely develops an ability to breathe through mouth and hence, the medical emergency would exist in the complete absence of patent both nasal cavities.

Embryological theories

• Hengerer and Strome proposed four factors to relate the embryological origin with the development of congenital CA.

1. Persistence of buccopharyngeal membrane of anterior intestine;
2. Failure of Hochstetter bucconasal membrane to rupture usually occuring in the seventh gestational week;
3. Abnormal adherence of the mesodermal tissue in the choanal region;
4. Abnormal guidance of mesodermal flow secondary to local factors.

• Other theories which are not so widely considered are:

1. Resorption of secondary nasal fossa floor
2. Incomplete extension of nasal cavity dorsally
3. Migration of dorsal part of frontonasal process to fuse with the palatal shelves

• However, none of these proposed pathologies gives a confirmatory support for an obstructive or minimalized size of the choanal openings by developmental processes, and hence, currently there has been no definitive evidence supporting one theory over the others.

Anatomical deformities

• Following deformitites are associated with CA:

1. The bony atretic plate is situated in front of the posterior bony septum
2. Narrowed nasal cavity
3. Thickening of lateral pterygoid plates compromises the nasal airway
4. Thickening of medial aspect of vomer
5. The membranous plate situated in between lateral pterygoid and vomer
6. High arched palate

Etiology

The exact cause of this anomaly is unknown but considered to be both genetic and environmental.

The Role of Retinoic Acid

• Retinoic acid (RA) is produced from vitamin A by an enzyme retinaldehyde dehydrogenase (Raldh) which is important for ontogenesis and homeostasis of numerous tissues.
• However, studies have revealed that cranio facial anamolies with mesenchymal damage and cell disruption were reported among mothers with an ingestion of high doses of vitamin A during gestation period. It has been attributed to disturbances in migration pattern of neural crest cells which further led to the disturbances in mesoderm development in the cranio facial area.
• Dupe et al.: Using a mouse model, they demonstrated that Raldh3 knockout suppressed RA synthesis and caused CA via following proposed mechanisms:

1. Over-expression of fibroblast growth factor 8 (FGF-8),
2. Persistence of nasal fins whose rupture normally allowed the communication between nasal and oral cavities

• They further demonstrated that the CA in the Raldh knockout mice could be prevented by maternal treatment of RA.
• The role of FGF-8 in CA development was supported by the observation of prevalent CA among patients with craniosynostosis syndromes as a result of the elevated level of FGF-8 expression.

The Role of Thioamides

• Thioamides: Methimazole, carbimazole, and propylthiouracil, are commonly used as medical treatment for hyperthyroidism.
• Several case reports have been published demonstrating the potential association of CA in the newborns whose mothers had prenatal use of thioamides for their thyroid hyperfunctioning.
• Moreover, Barbero et al. conducted a case- control study which further supported the relation of prenatal exposure to maternal hyperthyroidism treated with methimazole with CA development.
• Methimazole crosses the placenta and enters the fetal circulation which in turn reduces the T4 levels of the fetus. Therefore, infants born with CA have shown a marked decrease in their T4 levels.
• Teratogenic syndromes causing bilateral CA includes:

1. Methimazole embryopathy
2. Carbimazole embryopathy

• However, it is not completely supported because of lack of significant evidences.
• Maternal Hyperthyroidism: Although, based on the thorough study of case reports and critical literature reviews, it was stated that the mother’s hyperthyroidism rather than the methimazole treatment might be the causal factor for CA.
• Elevated thyroid-stimulating hormones (TSH) level was associated with increased level of FGF, FGF receptor, and other proliferating growth factors, which hypothetically form the basis for CA development.
• Hence, further studies are required to further delineate the causes and pathogenesis of CA.

Excessive Coffee Intake

Excessive consumption of coffee in the form of more than 3 cups/day increases the chances of CA by interrupting the membrane rupture which leads to an outgrowth of palate towards the medial side and further blocks the communication between the nasal cavities and the pharynx.

Genetics

• Familial cases: About 8%.
• Multifactorial trait: The fact is supported by both affected successive generations and affected single generations.
• CHARGE syndrome: The abnormalities in the chromodomain helicase DNA binding protein-7 (CHD7) gene have been identified in 64% of patients diagnosed with CHARGE, and hence, allowing screening of the gene for patients with CA and other related anomalies. However, the exact function of the CHD7 gene is largely unknown.

Differentiating Choanal atresia from other Diseases

Following conditions must be ruled out in any neonates, infant or child presented with acute or frequent episodes of nasal or upper airway obstruction.

Conditions mimicking Choanal Atresia
Antrochoanal polyp Chordoma Deviated nasal septum Dislocated nasal septum Hematoma Isolated piriform aperture stenosis Nasal dermoid Nasal harmatoma Nasal haemangioma Nasal cerebral heterotopia (glioma) Nasolacrimal duct cyst Encephaloceles: the encephaloceles can be frontonasal, frontoethmoidal or frontosphenoidal Turbinate hypertrophy

Epidemiology and Demographics

• “Rule of 2:1” states the ratio of unilateral to bilateral CA, female to male and the right sided to the left sided CA.
• The incidence is 1:5,000 to 1:8,000 per live-born children.
• Although its incidence is rare, it represents the most common congenital abnormality of the nose.
• Maternal age and parity does not affect the frequency of this congenital anomaly.
• Slightly increased risk exists in twin pregnancy.
• It is observed with equal frequency among all races and hence, no racial or ethnic preference is seen.

Risk Factors

• The relation of risk factors and its implications is always complex. A risk factor increases the predisposition towards a disease in comparison to an individual with no risk factors. However, some risk factors are more important than others; hence, acquiring a single or multiple risk factor does not mean that one will develop the disorder. Moreover, absence of a risk factor does not guarantee the disease free state.
• 2010: An epidemiological report found higher associations between increased incidence of CA and exposure to second-hand-smoke, coffee consumption, high maternal zinc and B-12 intake and exposure to anti-infective urinary tract medications.
• 2012: Another epidemiological study studied “atrazine” a commonly used herbicide in the U.S. used to treat agricultural crops, and found that women who lived in counties in Texas with the highest levels of this chemical being were 80 times more likely to give birth to neonates with CA in relation to women who lived in the counties with its lowest levels.
• To sum up, the risk factors for the development of Choanal Atresia are following listed:

1. Exposure to chemicals (atrazine) and medications (methimazole) that act as endocrine disrupters during gestation.
2. Exposure to secondhand smoke during gestational period.
3. Excessive consumption of coffee by pregnant mothers exposes the developing fetus to caffeine
4. Elevated levels of vitamin B-12 and zinc in a pregnant woman exposes the fetus to the same
5. Multiple pregnancies, such as twins, carries a higher risk
6. Presence of certain congenital disorders that are associated with Choanal Atresia including Crouzon syndrome, Antley-Bixler syndrome, and Pfeiffer syndrome further increase its chances of development.

Screening

When neonate/infant/child presented with a nasal/upper airway obstruction or respiratory distress, CA must be screened with other differential diagnosis and anomalies.

Clinical Associations and Complications

Any condition that causes significant depression of the nasal bridge or midface retraction can be associated with it.

Syndromic associations	Single anomalies associations
CHARGE syndrome Crouzon syndrome DiGeorge syndrome Amniotic band syndrome Fetal alcohol syndrome Treacher Collins syndrome Pfeiffer syndrome Antley-Bixler syndrome Down’s syndrome	Intestinal malrotation Craniosynostosis Congenital heart disease Polydactyly Nasal / auricular deformities Palatal deformities Mid face hypoplasia Meningocele Menigoencephalocele

CHARGE Syndrome

• The most commonly associated congenital anomaly.
• Choanal atresia is present in 10 to 30% of CHARGE syndrome cases.
• It elaborates as following:
  • C- Coloboma: of the iris, choroid, and/or microphthalmia
  • H- Heart disease: such as atrial septal defect (ASD) and/or conotruncal lesion
  • A- Choanal atresia
  • R- Mental and growth retardation
  • G- Genitourinary abnormalities: such as cryptorchidism, microphallus, and/or hydronephrosis
  • E- Ear deformities: associated deafness (the external, middle, and/or inner ear may be involved).

Prognosis

• The prognosis is usually considered to be very good with timely and effective management unless other complex syndrome associations seen.
• Full recovery is expected with no possibility for any long term problem in both groups of patients.

Clinical presentation

Clinical presentation of CA varies from acute airway obstruction to chronic recurrent sinusitis depending on whether CA is unilateral, bilateral, or associated with other coexisting airway abnormalities.

Characteristics	Bilateral	Unilateral
Onset of symptoms	Immediately after birth	Typically presents later in life
Severity	Can be life threatening	Relatively low morbidity
Nursing difficulties	Sucking disabilities; Inability to nurse and breathe at same time	Uncommon
Respiratory distress	Acute or cyclical episodes seen with intermittent cyanosis characteristically relieved by crying	Uncommon until obstruction of the contralateral side from infection or adenoid enlargement precipitates airway obstruction symptoms
Respiratory infections	Common due to aspiration	Common due to persistent mucoid rhinorrhea, and/or a history of chronic sinusitis
Recurrent nasal allergies	Common due to inability to clear nasal secretions	Common due to purulent nasal discharge accumulated over several weeks
Cyanosis	Worsens while feeding and improves on crying (paradoxical cyanosis)	Uncommon
Crying	Abnormal	Change in voice noted due to loss of normal nasal intonation (Rhinolalia clausa)
Stridor, Grunting, Snorting	Common	Uncommon
Foul smelling breath	Common	Common either due to mouth breathing and its attendant drying effects, or due to the inability to clear the nasal cavity of its secretions
Failure to thrive	Common due to feeding difficulties	Uncommon
Loss of sensation of smell	Common due to accumulated nasal secretions	Common
Multiple failed extubation attempts	Common especially in those with secondary airway issues	Uncommon
Timing of diagnosis	Improved respiratory distress after crying may delay the diagnosis	Usually delayed until adulthood due to the non-specific symptoms of unilateral nasal obstruction
Treatment	Timely airway management and surgical repair	Delayed until the later age

Effect of CA on the facial structures growth: The face, specifically the maxilla and mandible, grows in a dynamic fashion throughout childhood under the influence of bony deposition and resorption, soft-tissue contouring, and hormonal influences. In a reciprocal fashion, the skull base or neurocranium influences midfacial development via the growth of the sinuses, which in turn influence the skull base. Displacement of these structures of the nasomaxillary complex occurs in horizontal, vertical, and anteroposterior axes. These changes ultimately affect the proportions of the face and the morphology of all other facial structures, including the upper airway. Hence, upper airway obstruction while breathing is common because the intraoral airway has foreshortened due to abnormal placement of anterior choanal aperture, and further the diagnostic visualization of the laryngeal structures becomes difficult. Moreover, a chronic case of CA may progress to the development of obstructive sleep apnea.

CA with Multiple Congenital Anomalies:

• Other airway abnormalities: About 34% have other respiratory anomalies such as tracheomalacia, laryngomalacia, and subglottic stenosis
• Craniofacial abnormalities: About 21% had it in the form of CHARGE, Treacher Collins, Pfeiffer, Apert, Mandibulofacial dysostosis, and Crouzon syndromes.
• Hence, this subgroup of patients always presents with more acute and severe respiratory symptoms due to the underlying complex airway abnormalities and hence, they requires stable alternative airway management such as tracheostomy in addition to the surgical correction of CA.

Diagnosis

• The diagnosis and management of CA requires the combined and coordinated efforts of both the neonatologists and otolaryngologists. Due to its associations with other syndromes (Table 6), infants born with CA often need other subspecialty evaluations for an interprofessional approach from the departments of cardiology, ophthalmology, gastroenterology,geneticists, etc in the multidisciplinary settings especially for Pediatric Airway Disorders.

• A thorough diagnostic work up is required to rule out other clinical conditions (Table 5) to arrive at a definitive diagnosis and to make a timely diagnosis as if left unestablished till later ages, it tend to impair the quality of life through repeated hospital visits.

• Aero-digestive evaluation: An infant diagnosed with CA must be evaluated for both airway and feeding issues which need to be addressed by speech pathologists and GI specialists respectively.

• Following methods can be employed to diagnose the condition accurately.

1. Assessment of detailed history including the maternal drug intake history and symptoms should be done as mentioned in Table 8.
2. A thorough diagnostic physical and radiological examination procedures should be done.
3. Ultrasonography of the cardiac and renal systems can be performed for possible syndromic associations.
4. Breath sounds can be heard with either a stethoscope or a Toynbee auscultation tube.
5. Air can be gently blown into each nasal cavity with a Politzer bag.

Suction catheter test

• After performing proper preparation by the use of nasal decongestants and nasal suctioning, a fine six or eight French suction catheter introduced into the nose via each nostrils and into the child's oral cavity.
• If there is no atresia the catheter will effortlessly pass through the nasal cavity into the nasopharynx.
• The distance of encountered resistance can provide insights into the etiology of nasal obstruction.
  • If there is CA then a typical solid feeling would be encountered at about 3-5 cm cms from the alar rim and indicates obstruction at the level posterior choanae.
  • If obstruction is encountered within 1-2 cms from the anterior nares/ alar rim, then it could be caused due to traumatic deflection of nasal septum due to trauma during delivery or inferior turbinate pathologies. If obstruction is due to mucosal oedema it can be shrinked using nasal decongestants like oxymetazoline / xylometazoline.
• Hence, an inability to pass nasogastric tube through nasal cavity beyond 3-4 cm despite aerated lungs on chest radiograph confirms the diagnosis. However, care must be taken in patients with other craniofacial abnormalities to prevent intracranial passage of the catheter.

Cotton wisp test

• Movement of a wisp of cotton wool held directly underneath the nares during inspiration and expiration while the mouth is closed. It would move in the presence of air flow; however, the lack of movement indicates the diagnosis.

Laryngeal mirror test

• A shiny laryngeal mirror held under the nares will reveal nasal misting in patients with patent nasal airways. Contrarily, the absence of fog on a mirror when it is placed under the one nostril after the other to check for fogging indicates the diagnosis.

Acoustic rhinometry

• Acoustic rhinometry can be used for the diagnosis, but is especially helpful in the postoperative period to check the patients on restenosis.

Methylene blue dye test

• Administration of methylene blue dye into the anterior nasal cavity can be seen passing through the nasopharynx. However, obstruction due to CA will prevent the flow into the nasopharynx and supports the diagnosis.

Automatic tympanometer

• It has been revealed that the novel method of screening for choanal atresia in newborns using the automatic tympanometer is simple, minimally invasive and highly reproducible with 100% sensitivity and specificity rate.

Genetic Screening

• The CHD7 gene screening test and other cytogenetic anomalies such as chromosome deletions detections related to the several syndromes (Table 7) associated with CA can be done.

Prenatal ultrasound

• The clinical presentation and diagnosis of CA is usually postnatal, hence the prenatal ultrasound diagnosis is rare, and very few cases have been reported in the literature. It can be suspected prenatally in the presence of nose anomalies, mainly nasal septal deviation or the presence of a single nostril.

Lateral skull X-ray

• The traditional method of diagnosis can be used with a lateral skull X-ray after filling the nose with radiopaque dye with the patient in a supine position, and demonstrating hold-up of the dye in the posterior nasal cavity.

Nasal Endoscopy

Source: www.entdev.uct.ac.za

Source: www.entdev.uct.ac.za

• An appropriate age-related otorhinolaryngology examination is performed directed to the nasal cavity. After aspiration of any nasal secretions and preparation of the nasal cavity, examination in very small children is performed with the 3.2-mm-diameter flexible endoscope. When possible, we prefer the 0° and 30° rigid endoscopes with a diameter of 4.0 mm or 2.7 mm. Direct visualization of the point of obstruction in the nasal passage with a flexible nasendoscope confirms the presence of an atretic plate in the choana. Therefore, it has become the preferred method for confirming the diagnosis.

CT scan

• CT scan imaging of the paranasal sinuses and skull base is virtually diagnostic modality of choice. It should be done after stabilization of the patient in supine position.
• Objective:

1. To confirm the diagnosis and it’s involvement on one or both sides.
2. To determine the anatomy of the atretic area, including the width of the Vomer bone and the medial displacement of the sides of the lateral wall of the nose.
3. To measure the thickness of the atretic plate and the presence and thickness of a bony plate.
4. To determine if any other sites of obstruction or differential abnormalities exist in the nasal, nasopharyngeal or sinus cavities.
5. To detect the abnormal anatomy required in surgical planning and in determining the choice of the operative technique to be used.

• Patient preparation before the scanning: A nasal decongestant (0.5% xy-lometazaline) is applied to reduce mucosal swelling 30 minutes prior to the CT scan, and suctioning of the nose done immediately before the CT scan to remove all nasal secretions in order to enable accurate radiological diagnosis as it is difficult to distinguish radiologically a membranous occlusion from mucus in the unprepared nose.
• CT scan technique:
  • Anatomical landmark: the level of the pterygoid plates in the axial plane. At this level the width of both posterior choanae at maximum stenosis and the maximum width of the inferoposterior vomer are measured. Below this level the hard palate is visualised and above this level structures within the nasal cavity make measurement difficult.
  • Scanning angle: The gantry is angled 5° cephalad to a plane parallel to the hard palate to interpret the images for the measurements of the posterior vomer, the choanal openings and the shape of the posteromedial maxilla.
  • Partial skull ossification: Conventional bone-window settings may not show the bony margins, hence high resolution bone filters may overcome this problem. One to 1.5 mm thick uncontrasted scans are obtained contiguously.
• CT scan findings:

1. Narrowing of the posterior nasal cavity with medial bowing and thickening of the lateral wall of the nasal cavity, with airway width < 3 mm.
2. Impingement and thickening at the level of the anterior aspect of the pterygoid plates
3. Enlargement of the posterior portion of the vomer, with or without a central membranous connection. In patients less than 8 years of age, the vomer generally measures less than 0.23 cm in width and should not exceed 0.34 cm; in children over 8 years, the mean vomer width is 0.28 cm and should not exceed 0.55 cm.
4. The mean width of the posterior choanal airspace in the newborn (measured from the lateral wall of the nasal cavity to the vomer) is 0.67 cm, increasing to 0.86 cm at 6 years and to 1.13 cm by 16 years of age.
5. An air-fluid level of the nasal secretions above the obstruction point can be seen.
6. Membranous atresias: Soft-tissue densities will be seen in the posterior choanae, and narrowing of the posterior choanae just anterior to the pterygoid plates.
7. Bony atresia: the thickness of the atretic plate should be taken for surgical planning.

• Disadvantages: The main disadvantages of using CT in pediatric populations are

1. High radiation exposure dose: due to an inadequate positioning of some patients in such an age group while achieving a scanning angle and imaging place necessitates the repetition of the scan, and hence, resulting in a subsequent increase in the radiation dose.
2. Sedation: Need for sedation to avoid movement artifacts, which render the examination of fine details less reliable. Using contrast material in the nose will help to overcome that.
3. Child’s lens: The angle of the imaging plane might increases the risk to it.

Treatment

• The patient should ideally be managed in a neonatal or paediatric intensive care unit with a combination of supportive, medical and surgical care. However, the treatment is essentially surgical which can be divided into emergent and elective definitive categories.

Objectives

1. To restore choanal patency,
2. Not to interfere with the patient normal craniofacial development,
3. To minimize invasiveness, and
4. To avoid recurrences.

Systematic treatment approach

1. Establish oral airway immediately to ensure breathing
2. Membranous atresia may be perforated upon passage of nasogastric tube
3. Surgical repair for alleviating respiratory symptoms and feeding difficulties
4. Postoperative scar, complications, & incomplete resection of atresia plate evaluation with bone CT

Severity assessment

• The severity of the anomaly is assessed by evaluating its laterality (unilateral or bilateral), the degree of obstruction affecting the child's breathing and feeding, and its associations with other anomalies; the treatment can be further divided into mild and severe cases.
• Treatment for mild cases: In mild cases where there is no significant respiratory distress or feeding difficulty treatment could include the following:
  • The condition may be managed by keeping the baby under close observation and providing him with supplemental oxygen periodically.
  • To keep the nasal passages clear of discharge and prevent any further impediments to nasal breathing, nasal saline may be administered to keep the nasal linings healthy.
  • Parents can opt to delay surgical correction of the nasal structure until the child is older as the anatomy of the region is more similar to that in adults.
  • In some of the unilateral cases, it is ideal to delay surgical treatment until the infant is at least 6 months old, when the operative field is larger and the opportunity for control during surgery is better.
  • When properly identified, unilateral atresia is ideally fixed before 5 years of age in order to avoid persistent unilateral nasal drainage, which can be socially and medically problematic.
• Treatment for severe cases: In severe cases where there is a life threatening risk, usually because of bilateral choanal atresia, there is no room for delays in treatment.
  • Surgery should be performed as soon as the patient is stable and has been evaluated for other anomalies.
  • There are different surgical approaches to dealing with choanal atresia and all of which are performed in an operating theatre under general anesthesia.
• To sum up, whether or not surgery is performed, if your infant suffers from choanal atresia, periodic evaluation is necessary to ensure normal functioning of the airways and to rule out the presence of any feeding issues. Feeding and swallowing issues may be persistent and it is advisable to seek specialized care from speech pathologists and gastrointestinal specialists. If the child suffers from a syndrome like CHARGE or has other congenital birth defects, it would be best to get subspecialty evaluations and coordinated care.

Airway Management

• It is the initial goal of treatment for infants with bilateral CA to maintain an adequate airway by inserting an oral airway to break the seal formed by the tongue against the palate to tide over an immediate crisis.
• An oral airway is generally adequate to temporarily secure an airway for several weeks in a newborn with bilateral choanal atresia and respiratory distress.
• It is important to realize that even bilateral choanal atresia is not always a surgical emergency (despite the presence of an innate reflex for nasal breathing), because it is possible to establish and maintain a patent airway with the use of a McGovern nipple or a cannula of Guedel or a standard feeding bottle teat or dummy with the tip cut off (Figure 9) to facilitate oral breathing.
• The preferred oral airway is McGovern nipple, an intraoral nipple with a large opening by cutting its end off, secured in the mouth with ties around the infant’s occiput. A small feeding tube can be placed through another hole in the nipple or alongside the nipple to provide feeding needs. This helps to buy time till the child has gained adequate weight to withstand corrective surgery.
• In the short-term this has the effect of stenting the oral cavity open to allow mouth breathing; however it is not a long-term solution.
• If a patient still fails to maintain an adequate airway, endotracheal intubation must be performed as the initial management.
• A tracheostomy may be required in patients with severe comorbidities but it is not necessary in cases of isolated (even bilateral) CA.

Role of tracheostomy

• This should be considered only on rarest of rare occasions when the patient is not able to adequately maintain oral airway.
• Tracheostomy may be required if the definitive surgical treatment needs to be deferred due to patient’s other comorbidities such as cardiopulmonary instability and multi-level airway obstruction.
• Patients with bilateral CA and CHARGE syndrome are more likely to fail atresia repair because of the following reasons:

1. More contracted nasopharynx in a lateral and/or vertical dimension,
2. Narrower posterior choanal region than those with isolated CA and
3. Poor tongue/pharyngeal muscle control.

• Moreover, Asher et al. in their retrospective review of patients with CHARGE syndrome demonstrated that early repair of their CA was rarely successful as patients had a propensity for airway instability which leads to hypoxic events.
• Therefore, recommended early tracheotomy rather than early CA repair to secure the airway for CA patients with CHARGE syndrome.

Feeding Issues

• Do not feed in the cases where there is high index of suspicion for CA.
• A feeding tube is required due to the increased risk of aspiration which should be established via orogastric tube until surgical correction of the atresia is performed.

Timing of Surgery

• The exact timing of surgery is variable and decided upon studying the entire situation.
• If the infant learns to breathe orally, surgery may not be required as urgently and can be delayed for a while.
• Urgent surgery required in following cases:

1. Bilateral CA;
2. Symptomatic unilateral CA;
3. Syndromic babies with respiratory complications from unilateral atresia.

• Delayed surgery till the child reaches its first birthday in asymptomatic unilateral atresia because

1. This allows the surgery site to enlarge thereby reducing the risk Of post op stenosis.
2. Bleeding is also reduced if surgery is delayed.
3. Older infants tolerate stenting better than young ones.
4. The younger the patient, the higher the risk of intraoperative and postoperative complications and re-stenosis.

Use of Anaesthesia

• The anesthetic approach depends on the child's condition. In general, intravenous induction with a muscle relaxant of intermediate duration, endotracheal intubation with an oral Right Angle Endotracheal (RAE) tube, and maintenance with an inhaled agent and opioid or propofol and remifentanil infusion suffice.

Surgical Approaches

• Since Emmert's initial trocar perforation in 1853, the five different surgical approaches to correct choanal atresia have been described which includes the following:

1. Transnasal,
2. Transpalatal,
3. Transseptal,
4. Sublabial trans-septal,
5. Transantral and
6. External rhinoplasty.

• As per the research done in March 1999 by ASPO (American Society of Pediatric Otolaryngology), the most used techniques in descending order are:

1. Transnasla with endoscope use,
2. Transpalatal, perforation with Fearon dilator,
3. Transnasal with microscope use
4. Transnasal with laser use

• The transasal technique is slightly better than the transpalatal technique.

Transpalatal approach

• The transpalatal approach was the most frequently used until the advent of the endoscopic endonasal approach.
• In rare circumstances where the skull base is abnormally developed, the atresia is thick or other craniofacial anomalies are present, the surgeon may need to use a transpalatal approach to reach the area of choanal atresia through the roof of the mouth.
• Operating procedure: This procedure is performed under general anaesthesia and considered more suitable for bilateral choanal atresia. A Dingman-Denhardt mouth gag with the infant tongue blade is used. The palate is injected with 0.5% lidocaine with 1:200,000 epinephrine in the area of the mucosal incision which serves the dual purpose of helping in flap elevation and providing much needed hemostasis during the entire surgical procedure. A Owens type (U-shaped) mucosal incision is made beginning just behind the maxillary tuberosity on one side and then continued medial to the alveolar ridge up to the canine region and then angled back to the nasopalatine foramen. A likewise incision is made on the opposite side and the mucosal flap is elevated taking care not to damage the greater palatine arteries. Mucosa of the nose and nasopharynx is elevated up to the edge of the hard palate and preserved. The soft palate is now retracted posteriorly and superiorly exposing the posterior edge of hard palate. This area is the area for dissection. Then the palatine bones posterior to the greater palatine foramina, the atresia plates and the posterior vomer are carefully drilled away using a kerrison’s punch or drill. Two 14 or 16 French catheters are passed simultaneously into each nostril to check the patency of the newly created choanea. The preserved mucosa is then used to cover the superior and inferior surfaces of the newly formed choanea and then sutured in place to cover the bone. Stents are left in place for 4 weeks.
• Advantages:

1. Better visualisation and exposure
2. Both hands are free
3. Less stenting period (a portex endotracheal tube can be cut and used as a stent)
4. Less failure rate

• Disadvantages:

1. The incisions, which are identical to those for a cleft palate repair, may have a banding effect on maxillary growth due to scar formation. (Therefore, most surgeons prefer to wait to use this approach until some teeth are in occlusion - at approx.12-18 months).
2. Palatal growth can be stunted in 50 % of individuals
3. Increased blood loss due to a higher risk of injury to the greater palatine artery
4. Increased risk of development of palatal fistulas post operatively
5. Other post op complications include restenosis of the choanae, palatal fistulas, flap necrosis, bleeding, fistulas, infections and growth defects of the jaw and the palate bone and orthodontic problems, like cross bite.

• Care of the post op patient:

1. The parents must be taught to maintain the stents with frequent suction and a saline-moistened pipe cleaner or cotton applicator 3 to 6 times per day.
2. Antibiotics and decongestants are prescribed if there is evidence of rhinitis
3. Patients must be followed up regularly till the stents are removed.

Transseptal approach

• The transseptal approach is effective but is used very little because of the resultant impairment of facial growth. However, it is considered effective in patients older than 8 years with unilateral CA and impractical in infants.
• An important technical point is the need to remove the posterior portion of the vomer.
• It permits better correction of any deviations of the septum, resection of the posterior part of the vomer and preservation of mucosal flaps for coverage of the bleeding area.12
• Complications of transeptal approach:

1. Pressure necrosis of columella
2. Plugging of stent
3. Displacement of stent
4. Palatal dehiscence
5. Maxillary hypoplasia causing malocclusion
6. Granulation tissue formation around the stents.

Sublabial approach

• The sub labial, trans-septal access has advantages and disadvantages similar to those of the trans-septal approach, and it further reduces the likelihood of postoperative granulation tissue formation and stenosis by avoiding surgical trauma to nasal mucosa.

Transantral approach

• Transantral access is the least-used approach, because it requires a well-developed maxillary sinus that is not present in infants and many older children and adults with choanal atresia. However, it permits an adequate exposure of the surgical field, allowing a quick check for any bleeding source, and reduced risk of damaging the sphenopalatine arteries, veins and nerves, but can significantly increase the risk of deformities of growing structures such as the maxilla and upper teeth.

Transnasal approach

• The growing experience in both instrumentation and technique in endoscopic sinus surgery have led many CHOP surgeons to make more frequent use of the endoscopic endonasal technique for the repair of choanal atresia due to the modern refinements of endoscopic techniques as it does not affect the growth of the mandibular arch, causes no malocclusions or cosmetic alterations to the face.
• For stable infants with choanal atresia, the endoscopic endonasal technique should be considered the first choice for the surgical treatment of choanal atresia as it offers a direct approach to the atretic plate, reduces intraoperative bleeding, reduces hospitalization time, lowers morbidity, faster post-operative recovery, and can be done safely on infants just a few days old. If the bony atretic plate is less than 3 mm in thickness, a transnasal approach is the most commonly recommended for membranous atresia or where bony plate is thin. The simplest procedure is perforation of the atretic lamina followed by dilatation.
• Definitive surgical correction by nasal endoscopic approach is performed when appropriate and when feasible (weight >2kg). Given the relatively low morbidity of unilateral CA, definitive treatment is delayed until a later age (>18 months of age), when possible, as the chance of successful surgical repair increases with age.
• Options include:
  • Endoscopic perforation for membranous types
  • Full choanal reconstruction
• Operating procedure using endoscopes: The surgery is performed under general anesthesia. The posterior nasal airway is opened using a combination of tiny scope, dilators, sinus instruments, ear curettes and drills. A self retaining nasal speculum is used to expose the nasal cavity and the atretic plate without causing trauma to the nasal vestibule. If the atresia is membranous in nature a simple perforation of the same under endoscopic guidance would suffice. The nasal cavity is decongested using 4% xylocaine with adrenaline in the concentration of 1 in 10,000 concentration. A 0° endoscope is used transnasally with a simultaneous view of the nasopharynx through a transoral 120° endoscope. It is important to use both the transnasal and transoral views in order to avoid potentially entering the anterior skull base. Under endoscopic guidance a mucosal incision is made and the mucosal flaps are elevated exposing the posterior vomer and lateral pterygoid lamina. A diamond burr on an angled hand piece is used to drill the atretic bony plate. It is perforated at the junction of the hard palate and the vomer. Incidentally this is the thinnest part of the atretic plate. To improve visualisation the inferior turbinate can be out fractured or even be trimmed. After drilling, care is taken to preserve the mucosal flaps. A silastic stent is placed into each nostril passing through the drilled neo choana. This helps in reducing the incidence of restenosis and crusting at the site of the bony atresia. Stent is kept in place for atleast 6 weeks. Opening made should be large enough to allow smooth passage of suction catheter. 3-4 size Endotracheal tube can be used as stent to prevent restenosis and maintain patency while the area heals. The size should be choosen carefully in such a way that it should be adequate to prevent restensosis and inadequate to cause nasal regurgitation. Sometimes stenting is not required as a recent meta-analysis found similar success rates for bilateral choanal atresia repair regardless of whether stents were used.7. These stents will be removed at the bedside or during an office visit in weeks to months, after the child demonstrates airway stability and feeding evaluation.
• Caution: While performing this procedure caution must be taken not to injure the sphenopalatine vessels behind the middle turbinate.
• Advantages:

1. This process is faster and easier
2. Blood loss is minimal
3. Can be performed in children of all ages who do not have associated external nasal deformities
4. Child can be immediately breast fed
5. Child can be discharged on the 3rd day itself

• Disadvantages:

1. Vision is highly limited especially in the new born
2. Inability to adequately remove enough of the posterior vomerine septal bone and prevent restenosis
3. Longer stenting time
4. Endoscopes do not offer binocular vision
5. Can not be done safely and with good results on patients with multiple nasal and nasopharyngeal anomalies.

Rhinoplasty

• Correction of CA using an external rhinoplasty approach is usually restricted to unilateral cases when the child is 1 year of age or older. The medial crura are separated, and the cartilaginous edge of the nasal septum is exposed. The mucoperichondrium and the mucoperiosteum are elevated to the region of the atresia. The atresia plate is then removed, and the posterior portion of the vomer is resected.

Stenting

• The effectiveness of using stents after choanal atresia repair is a controversial topic with some of the major complications following its use.

1. Formation of granulation tissue
2. Crust formation
3. Septal perforation
4. Persistent nasal discharge
5. Foreign body tissue reaction
6. Nasal alar erosion
7. Columellar pressure necrosis

Mitomycin-C

• The topical application of mitomycin C, an aminoglycoside which inhibit fibroblast growth and migration, was also suggested to reduce risk of restenosis after surgery and improve the healing process as it has not caused any systemic effects and anesthetic complications; however its use is still controversial.

Postoperative monitoring

• After the atresia is surgically corrected, the surgeon is often faced with the problem of restenosis; however, recent innovations have created optimism that the restenosis rate can be reduced.
• Newer endoscopic techniques with powered instrumentation along with the use of stenting and mitomycin-c have enhanced the safety and efficacy for choanal atresia repair.
• Patients with unilateral obstruction usually do well in the postoperative period and require no special monitoring. However, infants undergoing bilateral repair can exhibit partial or intermittent upper airway obstruction that persists for some time. The infant should be observed closely in the ICU with appropriate monitoring until breathing dynamics have normalized.

Surgical Complications

• The principal factors resulting in failure in microendoscopic surgery for the treatment of choanal atresia were:

1. Surgery performed too early,
2. Inadequate surgery exposure usually when associated with other malformations,
3. Inappropriate surgical technique with insufficient removal of the atresial plate and the posterior nasal septum, and
4. Inadequate postoperative follow-up.

Success Rate

• Successful CA surgical outcomes are influenced by the presence/absence of following factors:

1. Nasopharyngeal reflux,
2. GERD,
3. Age <10 days (associated with limited visualization in noses of neonates and limited resection of the vomer),
4. Bilateral CA with purely bony atretic plate
5. Associated syndromic malformations.

Prevention

• Currently, there are no known methods or guidance reported for the prevention of Choanal Atresia. However, pregnant women should consider the general health measures that may minimise the risk factors for the condition as listed in the "Risk Factors" section.

Tips to remember

• The key to a successful outcome, regard-less of surgical approach, is to create a large, 3-dimensional opening by a combination of following:

1. Puncturing the membranous obstruction
2. Widening the medial bony thickening of the medial pterygoid plate
3. Thinning the thickened vomer

• Postoperative considerations

1. After successful choanal atresia surge-ry the child should be extubated and can usually be managed on a general paediatric ward with regular nasal suc-tioning
2. Oral feeding is established as soon as possible
3. Postoperative nasal decongestant drops (0.5% xylometazalone) should be used for one week
4. Saline and steroid drops should be used for 2 weeks to reduce postoperative in-flammation and granulations

See also

• CHARGE syndrome
• choana

References

Template:WikiDoc Sources