One-Year Relapse of Mandibular Distraction for Hemifacial Microsomia Using Masseteric Botulinum Toxin Type A Injections.

[BACKGROUND] The relapse of hemifacial microsomia was thought to be highly related to the soft tissue envelope around the mandible angle mainly composed by masseter and medial pterygoid. According to the reason, we tried to apply masseter injection of type A botulinum toxin to weaken the soft envelope tension on the early stage post mandible distraction in adult HFM patients.

[METHODS] Eight patients diagnosed with HFM were studied and randomly assigned to an experimental or control group. Patients in the experimental group were treated with DO, orthognathic surgeries, autologous fat grafting, and bilateral masseter muscle injection with type A botulinum toxin. The patients in control group were treated with the same procedures as the patients in experimental group except for masseter muscle injection with type A botulinum toxin. The recurrence rates of both groups were evaluated and analyzed after nearly 1 year of follow-up.

[RESULTS] The mean recurrence rate was 26.30% ± 11.84% (range 7.62%-37.27%) in the 8 patients after 1-year follow-up. The relapse rate was 16.32% ± 7.78% (7.62%-26.22%) in the experimental group and 36.28% ± 1.03% (34.84%-37.27%) in the control group. There was a significant difference (P = 0.002) between the experimental group and the control group.

[CONCLUSIONS] The combination of DO, orthognathic surgeries, autologous fat particle transplantation, and masseter muscle type A botulinum toxin injection technique could be a comprehensive treatment plan for adult patients of HFM. Furthermore, masseter injection of type A botulinum toxin might be an alternative method to reduce the early recurrence rate of postoperative adult patients of HFM.