A case of temporomandibular joint disorder subject to postoperative functional evaluation of open TMJ surgery on removal of adhesions and pseudowalls assisted by arthroscopy using electromyography of inferior head of lateral pterygoid muscles

• Published in: Journal of the Japanese Society for the Temporomandibular Joint Vol. 18; no. 1; pp. 6 - 11
• Main Authors: MORI Yui, GOTOH Motohiro, KUBO Hirohito, KAKUDO Kenji, IWAWAKI Yasuto, UCHIDA Shinji, INOUE Hiroshi, ARIKA Takumi
• Format: Journal Article
• Language: Japanese
• Published: 一般社団法人 日本顎関節学会 2006; The Japanese Society for Temporomandibular Joint
• Subjects: arthroscopic surgery; electromyography of the inferior head of the lateral pterygoid muscle; open ablative mobilization; temporomandiblar joint disorders; 外側翼突筋下頭筋電図; 開放剥離授動術; 関節鏡視下手術; 顎関節症
• ISSN: 0915-3004; 1884-4308
• DOI: 10.11246/gakukansetsu1989.18.6

We performed a postoperative functional evaluation using electromyography of the lateral pterygoid muscle in a patient with temporomandibular joint disorders who underwent open TMJ surgery. The patient was a 44-year-old male with chief complaints of trismus and pain of the left temporomandibular joint.Temporomandibular joint disorders (classification of JSTMJ: osteoarthritis), closed lock, and a stuck disc were noted on MRI. Exploratory pumping manipulation was performed, but was ineffective. Double contrast CT of the temporomandibular joint detected marked bilateral fibrous adhered lesions. Open TMJ surgery on removal of adhesions and pseudowalls assisted by arthroscopy was performed. We observed characteristic activities of the lateral pterygoid muscle (I-Lpt). Before surgery, muscular activity of I-Lpt was noted even when the mouth was closed, and no coordinated activity with the digastric muscle posterior belly of the mouth-opening muscles was noted.After surgery, I-Lpt acted in coordination with the mouth-opening muscles, and reciprocal activity with the mouth-closing muscles was noted.Regarding the jaw movement, limitation of right lateral movement was noted in the track of incisal point movement before surgery, but the range of protrusive and lateral movements increased after surgery. As for the movement of the heads of the mandible, the bilateral mandibular heads mainly showed hinge movement before surgery, but the range of movement of the left mandibular head increased in opening the mouth after surgery. This study revealed that pre-and post-operative functional evaluation using I-Lpt is useful. われわれは顎関節開放剥離授動術を施行した顎関節症患者の外側翼突筋の筋電図を使って術後機能評価を行った。患者は44歳男性, 主訴は開口障害および左側顎関節疼痛で, MRI所見にて顎関節症IV型クローズドロック, 円板はstuck状態であった。試験的パンピングマニピュレーションを施行するも奏効せず顎関節二重造影CTを行った結果, 両側に著明な線維性癒着病変を認め, 顎関節開放剥離授動術が適応となった。筋電図所見では特に外側翼突筋下頭 (以下I-Lpt) を指標とした筋電図で特徴ある所見が得られた。術前のI-Lptは閉口時にも活動し, 開口筋である顎二腹筋後腹との協調性活動はみられなかったが, 術後ではI-Lptは開口筋と協調的に活動し閉口筋との相反性活動がみられた。顎運動所見では術前の切歯点運動軌跡は右側側方運動時に可動制限があったが, 術後は改善され前突・側方運動ともに移動量が増加した。下顎頭運動所見では術前両側下顎頭は主に蝶番運動を行っていたのに対して, 術後は開口時左側下顎頭の運動範囲は増加した。今回I-Lptを指標とした術前術後評価は非常に有用であることが判明した。