A case of reformed coronoid process and mandibular angle after coronoidectomy and anglectomy for masticatory muscle tendon-aponeurosis hyperplasia

Abstract

Masticatory muscle tendon-aponeurosis hyperplasia is a newly defined disease entity in Japan, in which limited mouth opening results from limited masticatory muscle extension caused by hyperplasia of the tendon and aponeurosis. Recently, we encountered a rare case of reformed bilateral coronoid process and mandibular angle after coronoidectomy and anglectomy. A 19-year-old female with gradually progressive trismus had been diagnosed with this disease. Under general anesthesia, she received coronoidotomy of the bilateral coronoid process and anglectomy. At 1 week postoperatively, trismus was improved. At 6 months postoperatively, panoramic imaging showed the initiation of bilateral reformed coronoid process and mandibular angle. At 3 years postoperatively, computed tomography (CT) and three-dimensional reconstructed CT (3D-CT) demonstrated reformed coronoid process and mandibular angle. However, the maximum mouth opening length was not decreased. She continued to perform mandibular condyle movement exercise every day. Panoramic imaging is a very useful examination for evaluating bone reformation after coronoidectomy and anglectomy for masticatory muscle tendon-aponeurosis hyperplasia. In particular, CT and 3D-CT demonstrated reformed coronoid process and mandibular angle. Postoperative mouth-opening training is an important prognostic factor to prevent the recurrence of trismus in this disease.