Congenital Nasal Pyriform Aperture Stenosis: Evidence of Premature Fusion of the Midline Palatal Suture

BACKGROUND AND PURPOSE:Various etiologies have been theorized for the development of congenital nasal pyriform aperture stenosis (CNPAS). Imaging possibly implicates abnormal fusion of the midline palatal suture and deficient lateral growth of the midface in affected neonates.MATERIALS AND METHODS:A single-center, retrospective study was performed at a tertiary care pediatric hospital involving neonates and infants between 0 and 90 days of life. Maxillofacial CT scans of patients were reviewed. Abnormality of the palatal suture and midface transverse dimensions were measured and analyzed in patients with and without CNPAS.RESULTS:A total of 109 patients between 0 and 90 days of life had maxillofacial CT scans. Thirteen patients were classified as having CNPAS, 27 patients had normal scans (control group), and 69 patients were excluded because of the presence of other craniofacial anomalies. All patients with CNPAS had evidence of abnormal fusion of the midline palatal suture. Zero patients without CNPAS had a midline palatal suture abnormality. The mean widths of the pyriform aperture were 5.7 mm (SD, 1.7) in the CNPAS group and 13.1 mm (SD, 2.7) in the control group (P < .0001). The mean distance between the superior portions of the nasolacrimal ducts was 9.1 mm (SD, 2.1) in the CNPAS group, and the mean of the control group was 13.4 mm (SD, 2.2) (P < .0001).CONCLUSIONS:Patients with CNPAS have abnormal fusion of the midline palatal suture and exhibit lateral growth restriction of the midface. This may implicate synostosis of the midline palatal suture and abnormal midface growth.

Infants are obligate nasal breathers. As such, any degree of nasal airway obstruction may result in respiratory distress. Soft tissue edema caused by viral or idiopathic rhinitis is the most common cause of bilateral nasal obstruction in neonates. Less common, though clinically important, causes include choanal atresia and congenital nasal pyriform aperture stenosis (CNPAS).CNPAS was first described in 1988 and 1989 in the radiology and otolaryngology literature, respectively.^1,2 Since then, numerous case reports have highlighted 2 possible theories in the embryogenesis, as well as the presentation, diagnosis, and treatment.^3-8 Historically, the 2 theories of embryogenesis are bony overgrowth of the nasal process of the maxilla and a primary deficiency of the hard palate, with most studies citing the former as the cause. Classically, symptoms include respiratory distress relieved by crying, difficulty feeding, nasal congestion, apnea, and failure to thrive. Physical examination may raise the suspicion for CNPAS when a 5F suction catheter cannot be passed through either nasal cavity; note that choanal atresia could have a similar finding. The diagnosis requires a maxillofacial CT revealing the pyriform aperture width to measure less than 11 mm.^3,4 Associated imaging abnormalities include a median central incisor, a triangular-shaped palate, and a median palatal ridge. The presence of a median central incisor warrants further evaluation with MR imaging of the brain because it can occur as part of the holoprosencephaly spectrum.⁹ Genetic consultation may be useful to help define the presence of a syndrome. Treatment starts with medical therapy and, if needed, surgical therapy. Classically, surgical therapy involves drilling bone from the lateral extent of the pyriform aperture, though other entities such as dilation and rapid maxillary expansion have also been described.^3-13As part of the primary author''s previous work on CNPAS,¹¹ a unique, never described radiographic feature was noted. The midline palatal suture appeared abnormally ossified and potentially fused, raising the possibility that CNPAS may be related to lateral growth restriction of the midface akin to craniosynostosis. Other studies have shown that narrowing of the nasal cavity extends posteriorly to include the middle and posterior portions of the nasal cavity, supporting this theory.^3,14 With this in mind, we hypothesize that patients with CNPAS have abnormal midline palatal sutures and decreased midface dimensions compared with a control population.