閉口筋群の拘縮由来と思われる開口障害を呈した筋突起および下顎角過形成を伴ったこう筋肥大症の２例

• Published in: Journal of the Japanese Society for the Temporomandibular Joint Vol. 16; no. 3; pp. 196 - 200
• Main Authors: KOBAYASHI Susumu, SATO Jun, KANEYAMA Keiseki, SEGAMI Natsuki
• Format: Journal Article
• Language: Japanese
• Published: 一般社団法人 日本顎関節学会 2004; The Japanese Society for Temporomandibular Joint
• Subjects: hyperplasia of the coronoid process; hyperplasia of the mandibular angles; hypertrophy of the masseter muscles; trismus; 下顎角過形成; 咬筋肥大; 筋突起過形成; 開口障害
• ISSN: 0915-3004; 1884-4308
• DOI: 10.11246/gakukansetsu1989.16.196

Two males, aged 15 years (patient 1) and 27 years (patient 2), presented with chief complaints of pain in the bilateral masseter muscles during jaw movement and because of trismus. Hyperplasia of the mandibular angles and bilateral swelling of the masseter muscles were noticeable. The interincisal mouth opening of patients 1 and 2 was 31mm and 22mm, respectively. Radiography and magnetic resonance imaging did not reveal any abnormalities other than hyperplasia of the coronoid process and the mandibular angles. Bilateral hypertrophy of the masseter muscles with chronic trismus associated with hyperplasia of the coronoid process and the mandibular angles was diagnosed, and surgical procedures were applied using an intra-oral approach. Since there was little improvement in the passive range of interincisal mouth opening under general anesthesia with muscle relaxation and even after resection of the bilateral coronoid processes, the bilateral masseter muscles were stripped and partially resected. Stripping of the bilateral pterygoideus medial muscles and bilateral mandibular anglectomy were necessary to achieve a good range of interincisal mouth opening. We think that their trismus might have been caused by the contracture and difficulty in extending the jaw closing muscles. 患者は15歳と27歳の男性で顎運動時の両側咬筋部疼痛および開口障害を主訴に来院した。顔面は両側の下顎角の張り出しおよび咬筋肥大を認めた。開口域は31mm (症例1), 22mm (症例2) であった。画像所見では両側筋突起・下顎角の過形成を認めたが, 顎関節部には明らかな異常所見は認められなかった。開口障害を伴う両側咬筋肥大症および筋突起・下顎角過形成症の臨床診断のもと, 口内法による外科療法を行った。麻酔導入後の筋弛緩状態および筋突起切離後も開口域は2mm程度しか増加しなかった。咬筋部分切除および内側翼突筋剥離・下顎角形成後に開口域は著明に増加した。開口障害の主原因は閉口筋の拘縮および伸展障害による可能性が考えられた。