Tardive and idiopathic oromandibular dystonia: a clinical comparison

Objective-Most patients with tardive dystonia have a focal onset involving the cranial-cervical region. Because of its resemblance to idiopathic crani al dystonia, a common form of dystonia, it often poses a diagnostic problem . To compare clinical features and response to botulinum toxin (BTX) inject ions between patients with tardive and idiopathic oromandibular dystonia (O MD). Methods-Patients seen in a movement disorder clinic who satisfied the inclu sion criteria for tardive or idiopathic OMD were studied. The clinical vari ables and responses to BTX between the two groups of patients were compared . In the tardive group, we also compared the clinical variables between tho se with oro-facial-lingual stereotypies, and those without. Results-Twenty four patients with tardive Ohio and 92 with idiopathic OMD w ere studied. There were no differences in the demographic characteristics. Most were women, with duration of symptoms longer than 8 years. The mean du ration of neuroleptic exposure was 7.1 (SD 7.9) years. Jaw closure was the most frequent subtype of OMD (tardive=41.7%, idiopathic=51.1%). Idiopathic patients were more likely to have coexistent cervical dystonia (p<0.05), wh ereas isolated OMD was significantly higher in tardive patients (p<0.05). L imb stereotypies, akathisia, and respiratory dyskinesia were seen only in t he tardive OMD. Frequency of ore-facial-lingual stereotypy was significantl y higher in the tardive than the idiopathic group (75.0% v 31.5%, p<0.0001) . The peak effect of BTX was similar in both groups. Conclusions-Oro-facial-lingual stereotypies were significantly more frequen t in the tardive than the idiopathic group. Presence of stereotypic movemen ts in the limbs, akathisia, and respiratory dyskinesias in patients with OM D strongly suggests prior neuroleptic exposure. Dystonia in tardive OMD is more likely to be restricted to the oromandibular region, whereas in patien ts with idiopathic OMD, there is often coexistent cervical dystonia. BTX is equally effective in both groups of patients.