JAPANESE JOURNAL OF ORAL & MAXILLOFACIAL SURGERY

Vol. 54 No. 1                     2008

ISSN: 0021-5163      UBIC: 151-J

ABSTRACT

A 30-year-old woman was referred to our hospital because of severe trismus, which had been present for 14 years. At presentation, she complained of a mass with tenderness in the left masseter muscle, and mouth opening was limited to 15 mm. Panoramic radiograpy showed a periapical radiolucency at the left lower second molar. CT disclosed erosion and destruction of the buccal surface of the cortical bone and sclerosing changes of the left ramus, suggesting osteomyelitis of the mandible. CT also showed a mass inside the masseter muscle adjacent to the cortical bone defect. On MR the mass was confirmed to be a tumorous lesion with T1-low and T2-high signal intensity. Although the left lower second molar was extracted, symptoms did not improve, and mouth opening decreased to 5 mm. The patient underwent surgical therapy, including excision of the scar tissue, incision of the masseteric fascia, and abradement of the temporal muscle, which led to a good clinical course with mouth opening of more than 40 mm. On the basis of the clinical course and histopathological findings, the definitive diagnosis was trismus due to intramuscular chronic inflammation, which was caused by odontogenic infection followed by longstanding osteomyelitis, and cicatricial contracture of the masseter. Keywords: chronic sclerosing osteomyelitis, mandible, masseter muscle, scar tissue, trismus.

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