Choanal atresia
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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 (Coloboma, Heart defect, Atresia choanae, Retarded growth and development, Genital hypoplasia, Ear anomalies/deafness).
- 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.
Based on the morphology: The atretic plate has a thickness of usually 4-6 mm which attaches 1 to 2 mm anteriorly to the posterior border of hard palate.
| 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% |
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 |
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 |
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. |
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Embryology
Origin: Development of the nasal cavity starts with neural crest cells migration from their origin in the dorsal neural folds and hence, the development of choanae takes place between the 4th and 11th weeks of gestation.
| Gestational week | Developmental process |
|---|---|
| 3rd and 4th week |
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| 5th week |
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| 8th week |
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| 10th week |
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- Normal anatomical relations of the atretic plate are as follows:
- Superior surface: Under surface of body of sphenoid
- Lateral border: Medial pterygoid lamina
- Medial border: Vomer
- Inferior surface: Horizontal plate of palatine bone
Pathophysiology
- Obligate nose breathers: In neonates, the epiglottis is more superiorly placed as compared to adult so when infant swallows, the larynx rises above epiglottis position and touch the nasopharynx and locks between soft palate and side of nasopharynx. Due to the elevated laryngeal position compared to the adult counterpart, newborns are obligate nose breathers until mouth breathing is established with the descent of the larynx approximately 4–6 weeks of life.
- During inspiration, the neonate sucks the tongue and the vacuum is created in the oropharynx which helps to move soft tissue of the floor of mouth up and back towards soft palate.
- During expiration the pressure in the airway causes soft palate to push forward against the soft tissue and tongue in the mouth, which further obstructs the oral airway.
- Interrelation of respiration, feeding and crying episodes:
- As the infants are obligate nasal breather, the oral airway is invariably blocked or used by them during normal respiration. Oral breathing is used by them only during crying.
- 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 its mouth is closed, especially during periods of sleep or during feeding.
- Feeding difficulty can be the initial alerting event in which the infants can present with progressive airway obstruction and choke episodes during 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 when the child opens the mouth widely, releasing the air obstruction and the cyanosis disappears. If the crying stops, the mouth closes and the cycle repeats itself.
- 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 development of cyanosis. The infant with bilateral choanal atresia develops rarely an ability to breathe through mouth and hence, the medical emergency would exist in complete absence of patent both nasal cavities.
- Hengerer and Strome attributed the CA embryological foundations to four factors which try to explain the embryological origin of congenital CA.
- Persistence of buccalpharyngeal membrane of anterior intestine;
- Failure of Hochstetter bucconasal membrane to rupture which usually occurs in the seventh gestational week;
- Abnormal adherence of the mesodermal tissue in the choanal region;
- Abnormal guidance of mesodermal flow secondary to local factors.
- Other not so widely accepted theories are:
- Resorption of secondary nasal fossa floor
- Incomplete extension of nasal cavity dorsally
- Migration of dorsal part of fronto nasal process to fuse with the palatal shelves
- However, none of these proposed pathologies gives a precise explanation for obstruction or minimization of the size of the choanal openings by developmental processes, and currently, there has been no definitive evidence supporting one theory over the others.
- Anatomical deformitites associated with CA includes:
- The bony atretic plate is situated in front of the posterior bony septum
- Nasal cavity is narrowed
- Lateral pterygoid plates are found to be thickened compromising the nasal airway
- Medially vomer is thickened
- The membranous plate lies in between lateral pterygoid and vomer
- High arched palate is common in these patients
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:
- Over-expression of fibroblast growth factor 8 (FGF-8),
- 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:
- Methimazole embryopathy
- 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 |
|---|
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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:
- Exposure to chemicals (atrazine) and medications (methimazole) that act as endocrine disrupters during gestation.
- Exposure to secondhand smoke during gestational period.
- Excessive consumption of coffee by pregnant mothers exposes the developing fetus to caffeine
- Elevated levels of vitamin B-12 and zinc in a pregnant woman exposes the fetus to the same
- Multiple pregnancies, such as twins, carries a higher risk
- 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
- 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.
- Assessment of detailed history including the maternal drug intake history and symptoms should be done as mentioned in Table 8.
- A thorough diagnostic physical and radiological examination procedures should be done.
- Ultrasonography of the cardiac and renal systems can be performed for possible syndromic associations.
- Breath sounds can be heard with either a stethoscope or a Toynbee auscultation tube.
- 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
- 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:
- To confirm the diagnosis and it’s involvement on one or both sides.
- 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.
- To measure the thickness of the atretic plate and the presence and thickness of a bony plate.
- To determine if any other sites of obstruction or differential abnormalities exist in the nasal, nasopharyngeal or sinus cavities.
- 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:
- Narrowing of the posterior nasal cavity with medial bowing and thickening of the lateral wall of the nasal cavity, with airway width < 3 mm.
- Impingement and thickening at the level of the anterior aspect of the pterygoid plates
- 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.
- 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.
- An air-fluid level of the nasal secretions above the obstruction point can be seen.
- Membranous atresias: Soft-tissue densities will be seen in the posterior choanae, and narrowing of the posterior choanae just anterior to the pterygoid plates.
- 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
- 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.
- 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.
- Child’s lens: The angle of the imaging plane might increases the risk to it.
Treatment
The only possible treatment is surgery to correct the defect. [1]
See also
References
Template:Congenital malformations and deformations of respiratory system