|Bilateral membranous choanal atresia in CT scan|
Choanal atresia is a congenital disorder where the back of the nasal passage (choana) is blocked, usually by abnormal bony or soft tissue (membranous) due to failed recanalization of the nasal fossae during fetal development.
It can be unilateral or bilateral.
- Sometimes, a unilateral choanal atresia is not detected until much later in life because the baby manages to get along with only one nostril available for breathing.
- Bilateral choanal atresia is a very serious life-threatening condition because the baby will then be unable to breathe directly after birth as babies are obligate nasal breathers (they mainly use their noses to breathe). In some cases, this may present as cyanosis while the baby is feeding, because the oral air passages are blocked by the tongue, further restricting the airway. The cyanosis may improve when the baby cries, as the oral airway is used at this time. These babies may require airway resuscitation soon after birth.
Sometimes babies born with choanal atresia also have other abnormalities:
Also any condition that causes significant depression of the nasal bridge or midface retraction can be associated with choanal atresia. Examples include the craniosynostosis syndromes such as Crouzon syndrome, Pfeiffer syndrome, Treacher Collins and Antley-Bixler syndrome.
Very few risk factors for choanal atresia have been identified. While causes are unknown, both genetic and environmental triggers are suspected. One study suggests that chemicals that act as endocrine disrupters may put an unborn infant at risk. A 2012 epidemiological study looked at atrazine, a commonly used herbicide in the U.S., and found that women who lived in counties in Texas with the highest levels of this chemical being used to treat agricultural crops were 80 times more likely to give birth to infants with choanal atresia or stenosis compared to women who lived in the counties with the lowest levels. Another epidemiological report in 2010 found even higher associations between increased incidents of choanal atresia and exposure to second-hand-smoke, coffee consumption, high maternal zinc and B-12 intake and exposure to anti-infective urinary tract medications. The anti-thyroid medication methimazole has been associated with the development of choanal atresia in rare cases if given during the first trimester of pregnancy.
Choanal atresia can be suspected if it is impossible to insert a nasal catheter. Also, if one notices a continuous stream of mucus draining from one or both nostrils, it could be a sign of an atresia. Another common sign is cyanosis in an infant while breast feeding, as breathing is dependent on nasal patency in this situation. Diagnosis is confirmed by radiological imaging, usually CT scan.
Temporary alleviation can be achieved by inserting an oral airway into the mouth. However, the only definitive treatment is surgery to correct the defect by perforating the atresia to create a nasopharyngeal airway. If the blockage is caused by bone, this is drilled through and stent inserted. The patient has to have this sucked out by an air vacuum machine . And in later life as a teenager or in early twenties the hole will have to be re-drilled larger.
In popular culture
In the movie City of Angels, Dr. Maggie Rice (played by Meg Ryan) correctly diagnoses the cause of a newborn baby's failure to thrive as due to choanal atresia.
- Choanol atresia, NIH PubMed Health, August 2011.
- Epidemiology of choanal atresia - the National Birth Defects Prevention Study, Vijaya Kancherla, University of Iowa, 2010.
- Choanal atresia - PubMed Health
- Sadek SA (January 1998). "Congenital bilateral choanal atresia". Int. J. Pediatr. Otorhinolaryngol. 42 (3): 247–56. doi:10.1016/S0165-5876(97)00142-0. PMID 9466228.
- Gosepath J, Santamaria VE, Lippert BM, Mann WJ (2007). "Forty-one cases of congenital choanal atresia over 26 years--retrospective analysis of outcome and technique". Rhinology. 45 (2): 158–63. PMID 17708465.