[A case of Satoyoshi syndrome complicating marginal gingivitis of the mandible and dislocation of the temporomandibular joint].

Satoyoshi syndrome is a very rare disorder, characterized by progressive painful intermittent muscle spasms beginning in adolescence. Universal alopecia, diarrhea, amenorrhea and bony deformities are also cardinal features of this syndrome. Skeletal abnormalities, such as joint deformity, epiphysial destruction and retarded growth, are observed in approximately half of patients. However, no bony changes have previously been reported in the region of the head. We present here a male patient with Satoyoshi syndrome. Muscle cramps began in the lower extremities when he was 13 years old, and gradually spread. At the age of 17 years, masticatory muscle cramps made it difficult to eat and speak fluently, and were considered a cause of malacia in this patient. Finally, recurrent severe cramps in the masseter muscles caused marginal gingivitis of the mandible, necessitated extraction of the teeth and caused dislocation of the temporomandibular joint. After treatment with dantrolen sodium at doses up to 150 mg/day, painful spasm decreased significantly. Since masticatory muscles can cause significant stress to the teeth and the temporomandibular joint, sufficient attention should be paid to the oral region to avoid complications in patients with Satoyoshi syndrome.