Analysis of sagittal anatomic structure of upper airway in patients with ankylosing spondylitis: computed tomography-based three-dimensional reconstruction

Abstract

Objective To investigate the characteristics of sagittal anatomic structure of the upper airway in patients with ankylosing spondylitis using three-dimensional reconstruction based on computed tomography (CT).Methods Thirty-one male patients with ankylosing spondylitis,aged 20-60 yr (AS group),and 41 common patients (male) without difficult airways,aged 20-60 yr (control group),who underwent spiral CT scan of the head and neck using Helical CT from January 2007 to February 2011 in our hospital,were enrolled in the study.Reconstructed images of the upper airway were obtained using AW4.4 workstation and six distances (D1-D6) and four angles (α-δ) were recorded and analyzed:(1)D1,the arc distance between the upper central incisor and root of epiglottis; D2,the distance between the upper central incisor and root of epiglottis; D3 and D4,the lengths of maxilla and mandible ; D5,the distance between the root of epiglottis and midpoint of glottis; D6,the distance between the end of mandible and midpoint of glottis; (2) angle α,the angle of line D2 and D5; angle β,the angle of line D2 and the lower edge of the upper central incisor to the midpoint of glottis; angle γ,the angle of line D4 and D6; angle δ,the angle of the point of the lower edge of the upper central incisor to the trailing edge of the hard palate and then to the root of epiglottis.Results Compared with control group,no significant change was found in D1,D2,D3,D4 and D5 (P ＞ 0.05),and D6,angle α and angle δ were significantly increased,whereas angle β and angle γ were decreased in AS group (P ＜ 0.05).Conclusion The anatomic structure of the upper airway has the characteristics of specific changes and a laryngoscope blade with a large degree of curvature may be helpful for successful tracheal intubation in patients with ankylosing spondylitis. Key words: Spondylitis, ankylosing; Tomography, X-Ray ; Imaging, three-dimensional ; Anatomy,regional