Effects of mandibular distraction osteogenesis on anesthetic implications in children with hemifacial microsomia

Background Hemifacial microsomia (HFM) is a congenital craniofacial malformation, and its features include hypoplasia and asymmetry in skeletal tissue and soft tissue. These features are usually associated with a difficult airway. Mandibular distraction osteogenesis can achieve mandibular advancement, but its effect on the subsequent laryngoscopic views has not been adequately documented. Aim The aim of this study was to determine the change in laryngoscopic views after mandibular distraction osteogenesis (MDO) in children with HFM and to examine the radiological changes after MDO by using computed tomography (CT)-based three-dimensional (3-D) airway reconstruction. Methods An observational prospective study was carried out in children with HFM undergoing MDO. All children underwent 3-D airway reconstruction preoperatively before the placement and removal of the distractor. The temporomandibular joint lesions in children were classified by the Pruzansky-Kaban classification. The Cormack-Lehane grade was assessed after induction under direct laryngoscopy. The relationship between difficult laryngoscopy and the Pruzansky-Kaban classification was assessed. Changes in the upper pharyngeal airway parameters and laryngoscopic views were analyzed. Results Forty children (ages ranging from 5 to 16 years, males = 26, females = 14) with HFM underwent 80 anesthesia for MDO. The incidence of difficult laryngoscopy before mandibular distraction was 5/12 (41.7%) in type IIa, 19/24 (79.2%) in type IIb and 1/4 (25%) in type III HFM. The mean difference in the incidence of difficult laryngoscopy before and after MDO was 33.3% (95% CI: -6.7% to 73.3%), 50.0% (95% CI: 8.4% to 91.6%), and 0% for type IIa, type IIb, and type III, respectively. In type IIb, 12/19 cases of difficult laryngoscopy became easy after mandibular distraction: this was associated with an increase in the palatopharyngeal and glossopharyngeal CT parameters (p < .05). In type IIa, 5/5 cases of difficult laryngoscopy became easy after mandibular distraction, and 1/7 cases of easy laryngoscopy became difficult laryngoscopy. However, there were no significant changes in the palatopharyngeal, glossopharyngeal, and hypopharyngeal CT parameters in type IIa and type III HFM (p > .05). Conclusions MDO can improve the laryngoscopic views in children with HFM. According to the Pruzansky-Kaban classification, children with type IIb showed the highest incidence of difficult laryngoscopy before MDO. After MDO, the improvement in laryngoscopic views under direct laryngoscopy in type IIb was related to the increase in the palatopharyngeal and glossopharyngeal volume.