Abstract
A 54-year-old man was referred to our hospital because of severe trismus. The amount of mouth opening was only 2mm. The patient had sustained blows to the face, and both masseter muscle regions had been strongly grasped. He was unable to open his mouth after the violence. Twenty days after the first injury, he was struck on both sides of the face again. After that, severe trismus occurred. The clinical diagnosis was trismus due to scars of the masseter muscle regions.
Incision of the masseteric fascia and abradement of the temporal fascia were carried out, and an interincisal opening of 47mm was achieved at the time of operation. Part of the masseter muscle was resected and examined microscopically. Most of the muscle fibrils had disappeared and been replaced by cicatricial fibrous tissue with hyalinization. Rehabilitation of mouth opening was done with infrared therapy and drug therapy, including muscular relaxants and cicatricial suppressors, postoperatively. A favorable clinical response was achieved, and mouth opening was 40mm 3 months after surgery.
