Abstract
Dystonia involving the tongue is a well-recognized feature of both primary and secondary tardive dystonia as well as oromandibular dystonia. However, primary focal lingual dystonia (PFLD) has rarely been described. We present the case of a patient with speech-induced PFLD. A 46-year-old woman was admitted to our hospital because of dysarthria owing to involuntary protrusion of her tongue. This movement occurred only when she attempted to talk and was suppressed when she chewed gum or bit chopsticks; we considered these activities to be sensory tricks. Involuntary movements in other body parts were not noted. The strengths of the facial and masseter muscles were normal. The sensory functions of the limb and face were normal. Further, the findings of laboratory examinations, including routine hematological, biochemical, and thyroid function studies were normal. Initially, the patient was treated with hydrochloric trihexyphenidyl; however she was intolerant to the treatment because of its anticholinergic side effects. Thereafter she was treated with a mouthpiece through which a sensory trick stimulus was applied. When she wore the mouthpiece, her dystonic tongue movement was fairly well controlled. Lingual dystonia is a relatively rare event and sometimes difficult to treat. Botulinum toxin is not commonly used to treat patients with lingual dystonia because of the risk of dyspnea and dysphagia. Several medications are used empirically but their effectiveness remains unknown. We highly recommend that such patients be treated with a mouthpiece through which a sensory trick stimulus is applied as this treatment does not have any adverse effect.
https://ror.org/02956yf07 
