Myositis ossificans traumatica of the temporalis muscle: a case report and diagnostic considerations

The present paper reported the case of a trauma-related myositis ossificans, with focus on considerations for a differential diagnosis process.

A 50-year-old male with a severe painful limitation (12 mm) of jaw opening referred a trauma to the right temporomandibular joint (TMJ) area occurring about 40 days before. Posttraumatic TMJ ankylosis was ruled out on the basis of negative magnetic resonance and cone-beam computerized tomography findings, and the patient underwent treatment with arthrocentesis, botulinum toxin injections, and physiotherapy on the basis of two diagnostic hypotheses, viz., an anchored disk phenomenon or a myofibrotic contracture of the right masseter muscle due to prolonged myospasm. After 4 months, jaw opening was slightly increased to 23 mm, but limitation and pain persisted. A new CT was performed to investigate for the emerging clinical picture compatible with traumatic myositis ossificans of the right temporalis muscle. Once the diagnosis was confirmed, the patient underwent surgery for coronoidectomy. At the 6-month follow-up, mouth opening was increased to up to 35 mm and pain was absent.

It is fundamental that patients suspected of having uncommon clinical pictures leading to mouth opening restriction are promptly referred to specialized centers, where the differential diagnosis process should be based on a comprehensive assessment taking into account for the potential etiologic factors described in the literature.