Peripherally Induced Oromandibular Dystonia Following Orthognathic Surgery.

[BACKGROUND] Peripherally induced movement disorders are hyperkinetic conditions triggered by peripheral trauma or surgical intervention. Oromandibular dystonia (OMD), a focal dystonia affecting the masticatory and lingual muscles, is the most common peripherally induced movement disorder within the stomatognathic system. However, OMD following orthognathic surgery has rarely been reported.

[OBJECTIVE] This study aimed to describe the clinical characteristics, latency, and treatment outcomes of patients who developed OMD after orthognathic surgery in a retrospective single-center case series of six patients.

[METHODS] This retrospective case series included patients presenting with involuntary orofacial movements after orthognathic surgery at Kyoto Medical Center between 2007 and 2025. Inclusion criteria were as follows: onset of OMD within three months following surgery, anatomical correlation, and patient-reported causality. Clinical features, surgical history, latency, and treatment outcomes were analyzed.

[RESULTS] Six patients (mean age 35.2 years) met the criteria. Four had mandibular prognathism, one had mandibular prognathism with tongue hypertrophy, and one had bimaxillary prognathism with open bite. All underwent sagittal split ramus osteotomy: two had additional Le Fort I osteotomy, one underwent intraoral vertical ramus osteotomy, and one had tongue reduction surgery. OMD subtypes included jaw closing (n = 2), tongue (n = 2), jaw opening (n = 1), and jaw deviation (n = 1). Mean latency to OMD onset was 39.5 days, while the mean delay before referral was 40.3 months. All patients were treated with botulinum toxin injections, resulting in symptomatic improvement. Notably, none of the surgeons initially recognized the association with surgery.

[CONCLUSIONS] OMD may occur as a possible peripherally induced sequela of orthognathic surgery. Although rare, it is likely underdiagnosed. Oral and maxillofacial surgeons should remain aware of this potential complication to facilitate timely diagnosis and appropriate management.