Cephalometric Predictors of Clinical Severity in Treacher Collins Syndrome

Background: The aim of this study was to identify cephalometric measurements associated with clinical severity in patients with Treacher Collins syndrome. Methods: A retrospective single-institution review of patients with Treacher Collins syndrome was conducted. Preoperative cephalograms and computed tomographic scans (n = 30) were evaluated. Fifty cephalometric measurements were compared to age-specific normative data using analysis of variance. These cephalometric measurements and the patient's Pruzansky classification were correlated to clinical severity using Spearman analysis. Clinical severity was defined as severe (required tracheostomy), moderate (obstructive sleep apnea, oral cleft, or gastrostomy-tube), or mild (absence of listed comorbidities). Cephalometric measurements with a strong correlation (r > 0.60) were identified as predictors of clinical severity. Results: Cephalograms of the study population contained 30 measurements that were found to be significantly different from normative data (p < 0.01). These measurements were related largely to maxillary/mandibular projection, maxillary/mandibular plane angle, mandibular morphology, facial height, facial convexity, and mandible/throat position. Ten of these 30 statistically significant measurements in addition to Pruzansky classification were found to be strongly correlated (r > 0.60) to clinical severity. These measurements include the following: mandibular projection/position (sella-nasion-pogonion, r = -0.64; hyoid-menton, r = -0.62); posterior facial height (posterior facial height/anterior facial height, r = 0.60; condyle-gonion, r = -0.66); maxillary/mandibular plane angle (sella-nasion-mandibular plane, r = 0.62; Frankfort horizontal-mandibular plane, r = 0.61; sella-nasion-palatal plane, r = 0.69; sella-nasion-symphysis, r = -0.69); and Pruzansky classification (r = 0.82). Conclusion: Specific cephalometric measurements of increased mandibular retrognathia, decreased posterior facial height, more obtuse maxillary/mandibular plane angle and more obtuse symphysis notch angle are strongly correlated to increased clinical severity in patients with Treacher Collins syndrome.