Influence of congenital facial nerve palsy on craniofacial growth in craniofacial microsomia

Facial muscles are of major importance in human craniofacial growth and development. The purpose of our study was to investigate whether congenital facial nerve palsy influences craniofacial growth in craniofacial microsomia. Fifty-one patients with unilateral craniofacial microsomia and no history of craniofacial skeletal surgery whose radiographs were taken after craniofacial growth was complete were included in this study. These patients were divided into groups in which the facial nerve was involved or uninvolved. The authors evaluated a total of seven measurement items to analyze the midface and mandibular asymmetry. Twenty patients had facial nerve involvement, and 31 had no involvement. None of the measurement items revealed any significant differences between the facial nerve-involved group and the uninvolved group within the same modified Pruzansky grade. There was no correlation between the type of facial nerve involvement and the measurement items. In relationships among the measurement items within each group, maxillary asymmetry was indirectly correlated with mandibular asymmetry or midline deviation through the occlusal plane angle in the uninvolved groups. However, in the facial nerve-involved group, the relationships disappeared. When the correlations in the facial nerve-involved group were compared with those of the uninvolved group, the relationships in the uninvolved group appeared more significant than in the facial nerve-involved group. The loss of relationships between the upper and lower jaw in the facial nerve-involved group might have been caused by subtle changes, which occur in midfacial bones and in the mandible due to facial nerve palsy. The main limitation of our study is that aside from facial nerve palsy, craniofacial microsomia has many factors that can influence craniofacial growth, such as hypoplasia of the mandibular condyle and soft tissue deficiencies.