the pathogenic mechanism of referred pain in the trapezius muscle and sternocleidomastoid muscle associated with temporomandibular disorders

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K19298
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 57070:Developmental dentistry-related
• Research Institution: Hiroshima University
• Principal Investigator: Horie Kayo 広島大学, 病院(歯), 歯科診療医 (50784253)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: 慢性疼痛 / 三叉神経脊髄路核

Outline of Final Research Achievements

As the pathogenic mechanism of temporomandibular joint-related pain, the inflammatory spread in the spinal nucleus of trigeminal nerve above the sensory nerve in the temporomandibular joint spreads to the vicinity of the of the　nucleus　ambiguus accessory nerve nucleus. The study was conducted under the hypothesis that it may cause chronic pain associated with. The expression of inflammatory cytokines was significantly increased in the spinal nucleus of trigeminal nerve, trapezius muscle and sternocleidomastoid muscle only in IL-6 and pp38 as compared with naive. Fluorescent immunostaining images of inflammatory cytokines, c-fos and pp38, spreading around the spinal nucleus of trigeminal nerve were observed.
It was suggested that the expression of inflammatory cytokines near the nucleus ambiguus, which is the accessory nerve nucleus, is involved in the induction of inflammation in the trapezius muscle and the sternocleidomastoid muscle.

Free Research Field

矯正歯科

Academic Significance and Societal Importance of the Research Achievements

顎関節症の関連痛には僧帽筋や胸鎖乳突筋の筋肉痛があり、この疼痛は慢性化する。現在、適応があるのはアンフェナクとインドメタシンの２剤で、またNSAIDsの効果に対して、アスピリン喘息などアナフィラキシー症状といった重篤な副作用を有するため、鎮痛薬の選択の困難性や効果の低さが指摘されている。
本研究では、慢性疼痛として中枢側にある三叉神経脊髄路核と副神経核の疑核に注目した。本研究の実験結果のみで、疑核での炎症性サイトカインの波及が持続的なものかは不明であったためさらなる研究が必要ではあるが、この炎症性サイトカインの浸潤性の発現が、顎関節症関連痛の慢性疼痛化の発症機序の一因となることが示唆された。