A 78-year-old man was referred to our hospital with mandibular trismus. Physical examination showed severe trismus and stiffness of the masseter and temporal muscles. The patient had no noticeable history of trauma. The clinical diagnosis was TMD. On the next day, the symptoms intensified. Tetanus was diagnosed on the basis of clinical course and symptoms such as trismus, facial grimacing, and stiffness of the masseter and neck muscles. The patient was immediately admitted to the intensive care unit. He was given antitetanic human immunoglobulin, tetanus antitoxin, antibiotics, dantroren, and midazolam. The patient recovered with tracheotomy and tracheal intubation. Opisthotonus, airway obstruction, and circulatory disturbance did not occur. Tetanus is a fatal infectious disease if early treatment is not appropriately performed. When examining patients with trismus, we should consider the possibility of tetanus and observe them carefully.
