両側筋突起および咀嚼筋腱・腱膜過形成症による開口制限に外科的治療が奏功した１例

概要

A 46-year-old woman was referred to our hospital seeking treatment for limited mouth opening. Restriction of mouth opening was first noticed 6 years ago, after treatment of a cervical spine bone fracture. She had a maximum mouth opening of 25mm, with slightly limited lateral and anterior mandibular movement. The patient had a square face with prominent masseter muscles and mandibular angles. A dense band of tissue, which became taut during maximal opening, was palpable along the anterior border of both masseter muscles. 3DCT images (bone window) showed bilateral hyperplasia of the coronoid process. MR imaging revealed thickened aponeurosis extending far into the anterior margin of the masseter muscles. The clinical diagnosis was restricted mouth opening due to bilateral hyperplasia of the masseter muscle aponeuorsis and coronoid process. Masseter muscle myotomy with aponeurectomy and coronoidectomy were performed bilaterally by an intraoral approach. The mouth opening improved to 53 mm immediately after the surgery. The postsurgical course was uneventful and she maintained a maximal range of mouth opening of 40 mm without pain and occlusal change. Shinshu Med J 69 : 253―259, 2021