Objectives: Oromandibular dystonia, which is characterized by stereotypic, task-specific, or sustained contractions of masticatory and/or lingual muscles, is frequently misdiagnosed as temporomandibular disorders or psychogenic disease. Diagnostic delay in oromandibular dystonia is not acceptable; thus, a screening tool that can distinguish this condition from a temporomandibular disorder may be helpful for medical professionals unfamiliar with involuntary movements or temporomandibular disorders.
Materials and methods: A questionnaire that included questions on the clinical features of oromandibular dystonia, such as stereotypy, task-specificity, sensory tricks, and morning benefit, and included questions to rule out temporomandibular disorders (total point range 0-40) was administered to 553 patients suspected to have involuntary movements.
Results: Based on a careful examination and the differential diagnosis, the patients were divided into four groups: oromandibular dystonia (n = 385), oral dyskinesia (n = 84), psychogenic (functional) movement disorder (n = 50), and temporomandibular disorders (n = 34). The questionnaire had a high level of internal consistency as measured by the Cronbach's α (0.91), and item-total correlation was significant (p < 0.001). The test-retest reliability on two separate occasions showed a significant correlation (p < 0.001). Mean total scores of the questionnaire significantly differed among oromandibular dystonia (32.0), temporomandibular disorders (10.4; one-way analysis of variance, p < 0.001), oral dyskinesia (21.0; p < 0.001), and psychogenic (functional) movement disorder (13.7; p < 0.001).
Conclusions: Findings of this study suggest that the present questionnaire is a simple diagnostic tool that is useful for tentative differentiation of oromandibular dystonia from temporomandibular disorders.
Clinical relevance: This screening tool can be used to distinguish oromandibular dystonia from temporomandibular disorders.
Keywords: Oromandibular dystonia; Questionnaire; Reliability; Screening; Temporomandibular disorders.