Facial Paralysis in Patients With Hemifacial Microsomia: Frequency, Distribution, and Association With Other OMENS Abnormalities.

Although facial paralysis is a fundamental feature of hemifacial microsomia, the frequency and distribution of nerve abnormalities in patients with hemifacial microsomia remain unclear. In this study, the authors classified 1125 cases with microtia (including 339 patients with hemifacial microsomia and 786 with isolated microtia) according to Orbital Distortion Mandibular Hypoplasia Ear Anomaly Nerve Involvement Soft Tissue Dependency (OMENS) scheme. Then, the authors performed an independent analysis to describe the distribution feature of nerve abnormalities and reveal the possible relationships between facial paralysis and the other 4 fundamental features in the OMENS system. Results revealed that facial paralysis is present 23.9% of patients with hemifacial microsomia. The frontal-temporal branch is the most vulnerable branch in the total 1125 cases with microtia. The occurrence of facial paralysis is positively correlated with mandibular hypoplasia and soft tissue deficiency both in the total 1125 cases and the hemifacial microsomia patients. Orbital asymmetry is related to facial paralysis only in the total microtia cases, and ear deformity is related to facial paralysis only in hemifacial microsomia patients. No significant association was found between the severity of facial paralysis and any of the other 4 OMENS anomalies. These data suggest that the occurrence of facial paralysis may be associated with other OMENS abnormalities. The presence of serious mandibular hypoplasia or soft tissue deficiency should alert the clinician to a high possibility but not a high severity of facial paralysis.