It has been suggested that temporomandibular joint luxation is more likely in cases with Parkinson's disease in the bed-ridden stage, than in other neurological diseases. A case examination found temporomandibular joint luxation frequent in cases accompanied by cervical retroflexion in the progressive stage. Cervical retroflexion is thought to promote temporomandibular joint luxation kinesiologically. Even in neurological disorders other than Parkinson's disease, neurological pathologies involved in the occurrence of temporomandibular joint luxation become clear by considering the posture of the neck and abnormalities of muscle tone.

A 33-year-old female patient with the chief complaint of jaw locking in the open position visited the emergency department of our hospital. The patient was treated by manual manipulation under the diagnosis of right temporomandibular joint (TMJ) dislocation, but the TMJ dislocation involuntarily occurred again. The patient was referred to our department from the emergency department. Mask-like face and left jaw deviation with tremor were observed. The maximum range of mouth opening could not be determined. On panoramic TMJ projections, the right condyle was observed slightly beyond the articular tubercle. On the other hand, the left condyle was observed at the central position in the mandibular fossa. The medical history was schizophrenia, insomnia, parkinsonism and neuroleptic malignant syndrome. Atypical antipsychotic drugs were taken for schizophrenia and insomnia. We made a diagnosis of oromandibular dystonia (mandibular deviation type). To temporarily relax the inferior head of the lateral pterygoid muscle, Gow-Gates mandibular nerve block was performed. Then, both intramaxillary and extraoral fixations were performed to prevent the recurrent oromandibular dystonia-associated mandibular deviation and TMJ dislocation. These fixations were released the next day. At a later date, drug dose was adjusted by her doctor at the Department of Psychosomatic Medicine. As of 6 months after the release of these fixations, the last clinical assessment was uneventful. Gow-Gates mandibular nerve block was effective for inhibiting the mandibular deviation, and these fixations were useful for preventing the recurrent mandibular deviation and TMJ dislocation.