martedì 21 novembre 2006
Pyriform aperture stenosis
There is narrowing of the anterior nasal passage (Figure 1 and Figure 2) due to overgrowth of the nasal processes of the maxilla (Figure 1 and Figure 2). The nasal septum appears thinned.
Diagnosis: Pyriform aperture stenosis
Pyriform aperture stenosis is an uncommon cause for nasal obstruction in the newborn period. The patient will typically present with dyspnea or apneic spells during feeding or the inability to pass a nasogastric tube. Clinicians will often suspect choanal atresia as this is a more common cause of these symptoms. The diagnosis is easily made with thin section CT images through the maxillofacial region which will demonstrate narrowing or obliteration of the anterior nasal passage with a normal appearing posterior nasal caliber and choana. A pyriform aperture width of less than 11 millimeters is diagnostic of stenosis.
The differential diagnosis for a child with nasal obstruction should include choanal atresia, choanal stenosis, pyriform aperture stenosis, nasopharyngeal encephalocele, sinonasal polyposis or mucous impaction.
A single frontal megaincisor is sometimes associated with pyriform aperture stenosis and is considered within the spectrum of holoprosencephaly. Therefore, when this finding is noted further imaging of the brain should be performed to rule out holoprosencephaly. The premaxillary portion of the maxilla originates from midline mesodermal tissue. The mesoderm is thought to have an inductive effect on the forebrain, causing this association.