4．経口内視鏡的筋層切開術

Endoscopic Treatment for Esophageal Achalasia：Per-oral Endoscopic Myotomy （POEM）

2008年に世界第一例の経口内視鏡的筋層切開術（per-oral endoscopic myotomy：POEM）が本邦で施行され1），それから15年以上が経過した．現在までに，当大学のみで3,200例超，本邦全体で6,000例以上に施行されている．本邦での成功率は97％以上，国際的にも95％以上であり，食道アカラシアに対する第一選択の治療法といえる．本稿では，3,000例を超える経験に基づいた診断の実際，そして治療における手技的な重要ポイントを概説したい．

Per-oral endoscopic myotomy （POEM） is an endoscopic treatment of achalasia. Since the world’s first case was performed in Japan in 2008, over 15 years have passed. More than 3,200 cases have been performed at Showa University alone, and over 6,000 cases have been performed throughout Japan. The success rate in Japan exceeds 97％. Internationally, the efficacy of POEM has been demonstrated to be equal to or better than surgical treatment in randomized controlled trials （RCTs） with Heller-Dor surgery ［The New England Journal of Medicine （NEJM） 2019］. Additionally, the superiority of POEM over balloon dilation therapy was proven in another RCT （NEJM 2011）. Based on the results of these two RCTs, POEM has become the standard treatment for achalasia and the first choice of treatment. Furthermore, when compared to Heller-Dor surgery, POEM has the decisive advantage of easily extending the myotomy on the esophageal side without leaving any external scars. Especially for typeⅢ in the Chicago classification, POEM is particularly the first choice. Technically, the double scope technique allows for a 2 cm myotomy on the gastric side, preventing both incomplete myotomy and post-POEM gastroesophageal reflux disease （GERD）.