PERIPHERALLY INDUCED OROMANDIBULAR DYSTONIA

Objectives-Oromandibular dystonia (OMD) is a focal dystonia manifested by involuntary muscle contractions producing repetitive, patterned mo uth, jaw, and tongue movements. Dystonia is usually idiopathic (primar y), but in some cases it follows peripheral injury. Peripherally induc ed cervical and limb dystonia is well recognised, and the aim of this study was to characterise peripherally induced OMD. Methods-The follow ing inclusion criteria were used for peripherally induced OMD: (1) the onset of the dystonia was within a few days or months (up to 1 year) after the injury; (2) the trauma was well documented by the patient's history or a review of their medical and dental records; and (3) the o nset of dystonia was anatomically related to the site of injury (facia l and oral). Results-Twenty seven patients were identified in the data base with OMD, temporally and anatomically related to prior injury or surgery. No additional precipitant other than trauma could be detected . None of the patients had any Litigation pending. The mean age at ons et was 50.11 (SD 14.15) (range 23-74) years and there was a 2:1 female preponderance. Mean latency between the initial trauma and the onset of OMD was 65 days (range 1 day-1 year). Ten (37%) patients had some e vidence of predisposing factors such as family history of movement dis orders, prior exposure to neuroleptic drugs, and associated dystonia a ffecting other regions or essential tremor. When compared with 21 pati ents with primary OMD, there was no difference for age at onset, femal e preponderance, and phenomenology. The frequency of dystonic writer's cramp, spasmodic dysphonia, bruxism, essential tremor, and family his tory of movement disorder, however, was lower in the posttraumatic gro up (p < 0.05). In both groups the response to botulinum toxin treatmen t was superior to medical therapy (p < 0.005). Surgical intervention f or temporomandibular disorders was more frequent in the post-traumatic group and was associated with worsening of dystonia. Conclusion-The s tudy indicates that oromandibular-facial trauma, including dental proc edures, may precipitate the onset of OMD, especially in predisposed pe ople. Prompt recognition and treatment may prevent further complicatio ns.