Preliminary study on change in the upper airway dimension in growing patients with Pierre-Robin sequence

Abstract

Objective: This study aimed to evaluate the changes in upper airway (UA) dimensions in growing patients with Pierre-Robin sequence (PRS).

Methods: The subjects were 23 PRS patients who had not undergone growth modification therapy or surgical intervention. Their lateral cephalograms were obtained longitudinally at mean ages of 8.81 (T0) and 14.05 (T1). Patients were categorized based on their SNB value at T0 (Criteria: -2 SD): Group-1 (very retrusive mandible, n = 13) and Group-2 (moderately retrusive mandible, n = 10). Skeletal and UA variables at T0 and T1, as well as ΔT0-T1, were statistically analyzed.

Results: At T0, Group-1 exhibited more retrusive maxilla and mandible (SNA, P < 0.01; SNB, P < 0.001), a more hyperdivergent pattern (facial height ratio, P < 0.05), and a more posteriorly positioned hyoid bone (H-PTV, P < 0.05), while Group-1 showed larger UA spaces (superior pharyngeal airway space [SPAS] and inferior pharyngeal airway space, all P < 0.05) than Group 2, which might indicate the existence of a compensatory response to maintain the UA patency. At T1, Group-1 maintained significantly retrusive maxilla and mandible (SNA and SNB, all P < 0.01), exhibited a less anteriorly positioned tongue (TT-PTV, P < 0.05), and displayed a more obtuse soft palate angle (SPA, P < 0.05) than Group-2. Between T0 and T1, Group-1 demonstrated significant increases in the hyoid symphysis distance (ΔH-RGN, P < 0.001), tongue length (ΔTGL, P < 0.01), and pharyngeal UA spaces (ΔSPAS and ΔPNS-ad2, all P < 0.001).

Conclusions: Even in growing PRS patients with severe mandibular retrusion, the UA dimensions increased due to forward growth of the mandible, repositioning of tongue and hyoid bone, and existence of compensatory mechanism.

Keywords: Pierre-Robin sequence; upper airway.

Figure 1

Cephalometric landmarks. Skeletal: S, sella; N, nasion; Ba, basion; Or, orbitale; Po, porion; Ar, articulare; Pt, pterygoid point; R, bisecting point between S-Ba; Go, gonion; ANS, anterior nasal spine; PNS, posterior nasal spine; HP, hard palate point; A, point A; B, point B; Pog, pogonion; Me, menton; RGN, retrognathion. Airway: AD1, adenoid point 1 (adenoid tissue on the PNS-Ba line); AD2, adenoid point 2 (adenoid tissue on the R-PNS line); TT, tongue tip; Td, dorsum of tongue; P, tip of the soft palate; Eb, base of the epiglottic fold; H, hyoidale (the most anterosuperior point on the body of the hyoid bone); C3, the third cervical vertebrae.

Figure 2

Skeletal and upper airway variables. A, Skeletal variables. 1, SNA (°); 2, SNB (°); 3, ANB (°); 4, SN-GoMe (°); 5, Ramus height (Ar-Go, mm); 6, Mandibular body length (Go-Me, mm); 7, Anterior cranial base length (S-Na, mm); 8, Gonial angle (°); 9, Posterior facial height (S-Go, mm); 10, Anterior facial height (N-Me, mm); 11, Facial height ratio: (S-Go/N-Me) × 100; 12, Mandibular body length/Anterior cranial base length ratio: (Go-Me/S-N) × 100. B, Upper airway variables. Hyoid bone 13, H-RGN (mm); 14, Mandibular plane (MP)-H (mm); 15, H-PTV line (mm); 16, H-C3Me line (mm); Tongue 17, TGL (mm); 18, TGH (mm); 19, Td-hard palate point (mm); 20, TT-PTV line (mm); Soft palate 21, SPL (mm); 22, SPT (mm); 23, SPA (°); Pharyngeal airway 24, SPAS (mm); 25, MPAS (mm); 26, IPAS (mm); 27, VAL (mm); 28, PNS-ad1 (mm); 29, PNS-ad2 (mm). See Table 2 for definitions of each landmark or measurement.