Botulinum Neurotoxin Injection for the Treatment of Recurrent Temporomandibular Joint Dislocation with and without Neurogenic Muscular Hyperactivity

The aim of this study was to compare treatment outcomes following intramuscular injection of botulinum neurotoxin (BoNT) in patients with recurrent temporomandibular joint dislocation, with and without muscle hyperactivity due to neurological diseases. Thirty-two patients (19 women and 13 men, mean age: 62.3 years) with recurrent temporomandibular joint dislocation were divided into two groups: neurogenic (8 women and 12 men) and habitual (11 women and 1 man). The neurogenic group included patients having neurological disorders, such as Parkinson’s disease or oromandibular dystonia, that are accompanied by muscle hyperactivity. BoNT was administered via intraoral injection to the inferior head of the lateral pterygoid muscle. In total, BoNT injection was administered 102 times (mean 3.2 times/patient). The mean follow-up duration was 29.5 months. The neurogenic group was significantly (p < 0.001) younger (47.3 years) than the habitual group (84.8 years) and required significantly (p < 0.01) more injections (4.1 versus 1.7 times) to achieve a positive outcome. No significant immediate or delayed complications occurred. Thus, intramuscular injection of BoNT into the lateral pterygoid muscle is an effective and safe treatment for habitual temporomandibular joint dislocation. More injections are required in cases of neurogenic temporomandibular joint dislocation than in those of habitual dislocation without muscle hyperactivity.