S4B-04 SESSION 4B: ORTHOGNATHIC / TREACHER-COLLINS QUANTITATIVE AIRWAY ANALYSIS OF C3DO COMPARED TO ISOLATED MDO IN SEVERE TREACHER COLLINS SYNDROME AIRWAY OBSTRUCTION

Abstract

Introduction: Counterclockwise craniofacial distraction osteogenesis (C3D0) has been shown to allow decannulation of complex Treacher Collins syndrome (TCS) airways not treatable with mandible distraction alone. The differential three dimensional airway changes of this condition remain unknown in comparison to isolated mandible distraction (MDO). Our objective was to quantitate airway changes before and after C3DO to determine the differential improvement at each level for surgical planning of future cases. Methods: CT scans from eight consecutive C3DO cases (mean age 8.3 years) were analyzed for three dimensional airway changes before and after surgery using Dolphin software. The airway was divided into naso-, oro-, and hypopharynx using previously published techniques. A similar analysis was performed on two TCS patients undergoing isolated MDO. Comparison was performed using Mann-Whitney U test with a significance set at p<0.05. Results: After C3DO the mean nasopharynx volume increased from 3700 to 7700 mm3 (109%), the oropharynx from 3900 to 8600 (118%) and the hypopharynx from 1410 to 3000 (110%), for a total airway increase of 124%. In comparison, isolated mandible distraction did not significantly increase the nasopharynx or hypopharynx, but increased the oropharynx volume 70%. Conclusion: C3DO creates an average 124% symmetric increase of the upper three airway levels from the subcranial rotation movement pivoted on the nasion, whereas isolated mandible distraction in TCS creates a smaller isolated single level oropharyngeal increase. In complex multi-level TCS airway, C3DO provides superior expansion to isolated MDO. MDO should be reserved for isolated oropharyngeal obstruction in this condition.