Quantitative Evaluation of Cephalometric Radiographs of Patients With Hemifacial Microsomia.

OBJECTIVE: To clarify the morphological characteristics of hemifacial microsomia (HFM) by quantitative analysis of cephalometric radiographs. DESIGN: Retrospective study of imaging data. SETTING: Imaging data were obtained from the records of Sapporo Medical University Hospital. PATIENTS: A total of 183 patients with HFM. MAIN OUTCOME MEASURES: We used linear and angular measurements and analyzed the middle face and lower face. RESULTS: The ratios of the affected side to the unaffected (A/U) side of the lateral distance of the mandibular condyle, the mandibular ramus height, and the length of the body of the mandible in the HFM group were significantly lower than in the control group. The inclination of the body of the mandible was significantly larger in the side with HFM than in the unaffected side, and the extent of the mandibular ramus was significantly lower than in the unaffected side. The A/U ratios of the extent of the angle of the mandible and the inclination of the body of the mandible in the HFM group were larger than in the control group. Moreover, the length and the inclination of the body of the mandible had significant correlations with the distance of the shift of the menton. CONCLUSIONS: It is suggested that improving the hypoplasia of the length of the body of the mandible and the extent of the angle of the mandible on the affected side will lead to more effective treatment of jaw deformity in patients with HFM.

Relationship Between Mandibular Ramus Height and Masticatory Muscle Function in Patients With Unilateral Hemifacial Microsomia.

OBJECTIVE: To clarify the relationship between mandibular ramus height and function of masticatory muscles in patients with hemifacial microsomia. DESIGN: Retrospective study of imaging and physiological data. SETTING: Images and physiological data were obtained from the records of Sapporo Medical University Hospital. PATIENTS: A total of 29 patients with hemifacial microsomia who showed Pruzansky grades I, II deformity. MAIN OUTCOME MEASURES: Mandibular ramus height and masticatory muscle volume were evaluated with multi-detector row computed tomography. The electromyographic value was measured by the K7 Evaluation System. The hemifacial microsomia patients were classified into three groups based on the mandibular ramus height ratio of the affected and unaffected sides: group 0, >1.00; group 1, 1.00 to 0.85; group 2, <0.85. The Tukey-Kramer method and Games-Howell method were used to determine correlations between parameters. RESULTS: Decreased mandibular ramus height was significantly correlated with both reduced electromyographic values of the masseter muscle (P < .05) and the amount of mandibular lateral deviation at the time of maximum opening (P < .05) on the affected side. These differences were prominent in unilateral hemifacial microsomia patients classified as group 2. CONCLUSIONS: Decreased mandibular ramus height may cause dysfunction of the masseter muscles but not the temporal muscle on the affected side in patients with hemifacial microsomia.