title: Congenital nasal pyriform aperture stenosis and single central maxillary incisor: preoperative evaluation with three-dimensional computed tomography.
abstract: OBJECTIVE
  Congenital nasal pyriform aperture stenosis (CNPAS) is an uncommon cause of nasal airway obstruction in neonates and infants. It is frequently associated with a single central maxillary incisor (SCMI). The purpose of this study was to assess whether 3-dimensional spiral computed tomography (3D spiral CT) could be used for the diagnosis of CNPAS and for detecting SCMI in CNPAS patients before tooth eruption.
  
  
  METHODS
  From January 1996 to December 2001, 16 patients (mean age, 2 +/- 3 months) with clinically suspected CNPAS and 13 normal control subjects (mean age, 28 +/- 32 months) were studied prospectively by 3D spiral CT. On the 3D CT image of each subject, the middle pyriform aperture width (MPAW), upper 1/4 PA width (UPAW), and middle internasal process width (MINPW) were measured. In addition, the ratios of MINPW to MPAW and of MINPW to UPAW were calculated. SCMI was identified as a bigger tooth with singular convexity.
  
  
  RESULTS
  SCMI was diagnosed in 11 of the 16 CNPAS patients. In the CNPAS patient group, the mean MINPW (5 +/- 1 mm) was significantly shorter than the mean MPAW (9 +/- 1 mm) and the mean UPAW (8 +/- 1 mm) [p < 0.001]. However, in the normal control group, the mean UPAW (13 +/- 2 mm) was significantly shorter than the mean MPAW (16 +/- 3 mm) and the mean MINPW (16 +/- 3 mm) [p < 0.01]. In the CNPAS patients, the mean ratios of both MINPW to MPAW (0.5 +/- 0.1) and of MINPW to UPAW (0.6 +/- 0.1) were significantly lower than the corresponding mean ratios in the normal control subjects (1.0 +/- 0.1 and 1.3 +/- 0.2, respectively; both p < 0.001).
  
  
  CONCLUSIONS
  Our results indicate that CNPAS is frequently associated with a SCMI and CNPAS patients have a significant reduction in the MINPW and in the ratios of MINPW to MPAW and of MINPW to UPAW. We conclude that 3D spiral CT can be used for diagnosis of CNPAS and for detecting SCMI in CNPAS patients before tooth eruption.
authors.affiliation: Department of Radiology, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Jon-Kway
authors.initials: JK
authors.lastname: Huang
authors.forename: Sho-Jen
authors.initials: SJ
authors.lastname: Cheng
authors.forename: Cheng-Chien
authors.initials: CC
authors.lastname: Yang
authors.forename: Chun-Ho
authors.initials: CH
authors.lastname: Yun
authors.forename: Shin-Lin
authors.initials: SL
authors.lastname: Shih
mesh_terms: D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007180:Incisor / Q000002:abnormalities / Q000000981:diagnostic imaging*; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008437:Maxilla; D009296:Nasal Cavity / Q000002:abnormalities / Q000000981:diagnostic imaging*; D015508:Nasal Obstruction / Q000151:congenital / Q000000981:diagnostic imaging*; D011300:Preoperative Care; D011446:Prospective Studies; D036542:Tomography, Spiral Computed