Sarah Goldfeder, MD, Brady Huang, MD, and Corey Sides, MD
Clinical
Presentation: A
4-day-old male was intubated for respiratory distress and inability to breath through his nose. There is clinical suspicion for CHARGE syndrome. CT of the maxillofacial skeleton is requested to evaluate for the possibility of choanal atresia or other facial anomalies.
Imaging Findings: Maxillofacial CT: There is narrowing of the anterior bony nasal aperture secondary to medialization of the nasal processes of the maxillary bones (Fig. 1). The nasal aperture measures approximately 4 mm in width. There is no evidence of choanal atresia. There is a single central megaincisor of the maxilla (Fig. 2). Brain MR: The sagittal images demonstrate a normal pituitary gland, corpus callosum, and cerebellar tonsils (Fig. 3). The ventricular system and subarachnoid space is normal (Fig. 4).
Figure 1: Medialization of the nasal processes of the maxilla causing narrowing of the nasal piriform aperture.
Figure 2: Single central megaincisor of the maxilla.
Figure 3: Normal pituitary gland, corpus callosum, and cerebellar tonsils.
Figure 4: Normal ventricular system.
Figure 5: 3D image shows the large central incisor in the mandible.
Discussion: The piriform aperture is the bony opening of the anterior nasal passage. It is bordered superiorly by the nasal bone, inferiorly by the nasal surface of the maxilla, and posteriorly by the horizontal plate of the palate. Congenital nasal piriform aperture stenosis (CNPAS) is an uncommon cause of nasal obstruction in the newborn caused by bony overgrowth of the nasal processes of the maxilla. It needs to be distinguished from the more common choanal stenosis and atresia. CNPAS presents as respiratory distress, cyanosis, and inability or difficulty in passing a nasogastric tube. Respiratory distress is often exacerbated during feeding and may be alleviated during crying episodes.
While CNPAS may be suspected clinically, the definitive diagnosis is made by a CT scan of the nasal cavity. Piriform aperture width of less than 11 mm in term infants is considered diagnostic. The choana may be smaller than usual, but it should not be stenotic. Other features include a hypoplastic triangular hard palate with an inferior midpalatal vomerine ridge and abnormal dentition, particularly a single or fused central maxillary megaincisor. CNPAS may also be associated with holoprosencephaly, pituitary insufficiency, clinodactyly, hypotelorism, and cleft palate. MR imaging of the brain is, therefore, recommended. There are two forms of CNPAS: the isolated form and the form associated with other abnormalities. If a central megaincisor is present, intracranial defects are more likely.
Two pathogenic mechanisms for CNPAS have been suggested: abnormal growth of the primary palate and bone overgrowth of the nasal process of the maxilla. Management is based on the severity of symptoms. Intubation and ventilation may be required. Prognosis is excellent, with many patients treated medically until their nasal cavities grow and overcome the obstruction. However, surgical enlargement should be considered if medical treatment is not successful after 10-15 days,
While our patient does have congenital piriform aperture stenosis with a central megaincisor, he does not have any intracranial abnormalities such as holoprosencephaly or an abnormal pituitary gland.
References:
Som and Curtin: Head and Neck Imaging, 4th ed., Volume Two. 2003 Mosby: 1540-1542.
Belden CJ, Mancuso AA, Schmalfuss IM. CT features of congenital nasal piriform aperture stenosis: initial experience. Radiology. 1999 Nov;213(2):495-501. [Medline]
Osovsky M, Aizer-Danon A, Horev G, Sirota L. Congenital pyriform aperture stenosis. Pediatr Radiol. 2007 Jan;37(1):97-9. [Medline]
Rollins N, Booth T, Biavati M. Case 40: congenital pyriform aperture stenosis. Radiology. 2001 Nov;221(2):392-4. [Medline]
