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NOTES revisited

      Abbreviations:

      NOTES (natural orifice transluminal endoscopic surgery), POEM (peroral endoscopic myotomy)
      In this issue, Liu et al
      • Liu B.-R.
      • Qiu X.-G.
      • Li D.-L.
      • et al.
      Flexible endoscopic transoral thyroidectomy: a pilot study in a porcine model (with video).
      report a pilot porcine study assessing the feasibility of flexible endoscopic transoral thyroidectomy. By the opening of a transoral incision, the endoscope was used to create a subcutaneous tunnel from the mouth to the thyroid gland to perform a partial thyroidectomy. The procedure was successfully performed in 6 swine, with a mean procedure time of 35 minutes, and none of the swine had adverse events.
      Research in natural orifice transluminal endoscopic surgery (NOTES) gained momentum in the early millennium after initial reports of Reddy and Rao performing a transgastric appendectomy.
      • Teoh A.Y.
      • Chiu P.W.
      • Ng E.K.
      Current developments in natural orifices transluminal endoscopic surgery: an evidence-based review.
      The report generated vast interest in the GI field, and we observed an exponential growth in the number of research projects and publications on the subject. Much of the initial focus in research was on how to adopt the NOTES approach to perform conventional surgical procedures like appendectomy and cholecystectomy. There was such a hype that dedicated sessions in major international conferences were organized, and most of the presented materials were on animal models. The ASGE/SAGES white paper then identified several obstacles that needed to be overcome before NOTES could be applied to clinical practice.
      ASGE/SAGES Working Group on Natural Orifice Translumenal Endoscopic Surgery White Paper October 2005.
      These obstacles included access to the peritoneal cavity, gastric (intestinal) closure, prevention of infection, development of suturing and anastomotic devices, spatial orientation, development of a multitasking platform to accomplish procedures, management of intraperitoneal adverse events, and others. Nevertheless, after a decade of research, the application of NOTES in human trials was still limited because the optimal target procedure could not be identified.
      • Rattner D.W.
      • Hawes R.
      • Schwaitzberg S.
      • et al.
      The second SAGES/ASGE white paper on natural orifice transluminal endoscopic surgery: 5 years of progress.
      However, several interesting spinoffs from NOTES research were adapted to clinical practice. They include the development of third- and fourth-space endoscopy and endoscopic suturing devices.
      The development of third- and fourth-space endoscopy is still in progress, but it represents yet another paradigm shift in therapeutic endoscopy. By the creation of a mucosal flap and submucosal tunneling, a safe luminal access could be created to reach submucosal or extraluminal lesions for intervention. The actual risk of a leak from the access is low as long as mucosal closure is secure, and the risk of causing infection in the extraluminal space is much lower than was initially expected before the development of NOTES. Our previous idea of a perforation being a major adverse event in luminal endoscopy is no longer valid, and “intentional” perforation is now a common step in these types of endoscopies. Peroral endoscopic myotomy (POEM) for achalasia is the star procedure in third- and fourth-space endoscopy.
      • Inoue H.
      • Minami H.
      • Kobayashi Y.
      • et al.
      Peroral endoscopic myotomy (POEM) for esophageal achalasia.
      Thereafter, we have witnessed the development of other novel procedures, including gastric POEM, diverticular POEM, and full-thickness resection procedures that use similar principles of submucosal dissection and tunneling.
      • Inoue H.
      • Ikeda H.
      • Hosoya T.
      • et al.
      Submucosal endoscopic tumor resection for subepithelial tumors in the esophagus and cardia.
      • Khashab M.A.
      • Ngamruengphong S.
      • Carr-Locke D.
      • et al.
      Gastric per-oral endoscopic myotomy for refractory gastroparesis: results from the first multicenter study on endoscopic pyloromyotomy (with video).
      • Yang J.
      • Zeng X.
      • Yuan X.
      • et al.
      An international study on the use of peroral endoscopic myotomy (POEM) in the management of esophageal diverticula: the first multicenter D-POEM experience.
      With increasing experience of endoscopic interventions in the third and fourth spaces, a renewed interest in NOTES procedures seems to be brewing.
      • Liu B.R.
      • Ullah S.
      • Ye L.
      • et al.
      Endoscopic transcecal appendectomy: a novel option for the treatment of appendiceal polyps.
      In the article by Liu et al,
      • Liu B.-R.
      • Qiu X.-G.
      • Li D.-L.
      • et al.
      Flexible endoscopic transoral thyroidectomy: a pilot study in a porcine model (with video).
      application of submucosal endoscopy to access the thyroid through the oral cavity represents another extension of fourth-space endoscopy. The novelty of the technique lies in the use of the GI tract to assess and perform thyroidectomy. However, the use of transoral access to the thyroid gland is not new. Endocrine surgeons have been performing laparoscopic and robotic transoral thyroidectomy, and the main benefit of the approach is the absence of a neck scar.
      • James B.C.
      • Angelos P.
      • Grogan R.H.
      Transoral endocrine surgery: considerations for adopting a new technique.
      Yet, the new approach also brings about new risks, including a higher risk of mental nerve injury, chin flap perforation, and oral commissure or inferior labial frenulum tear. Thus, to translate flexible endoscopic transoral thyroidectomy into human application, the endoscopist will need to become familiar with the neck anatomy to avoid potential adverse events. Improvements in endoscopic instruments will also be required to make the procedure more feasible. Furthermore, we will need to demonstrate obvious advantages of the flexible approach over the well-established laparoscopic or robotic transoral approach to gain popularity. Hence, similar to early NOTES experiments, the idea presented in the current study will be needed to overcome difficult challenges so as to be adopted to humans.

      Disclosure

      Dr Teoh is a consultant for Boston Scientific, Cook Medical, Taewoong Medical, and Microtech Medical.

      References

        • Liu B.-R.
        • Qiu X.-G.
        • Li D.-L.
        • et al.
        Flexible endoscopic transoral thyroidectomy: a pilot study in a porcine model (with video).
        Gastrointest Endosc. 2021; 93: 224-228
        • Teoh A.Y.
        • Chiu P.W.
        • Ng E.K.
        Current developments in natural orifices transluminal endoscopic surgery: an evidence-based review.
        World J Gastroenterol. 2010; 16: 4792-4799
      1. ASGE/SAGES Working Group on Natural Orifice Translumenal Endoscopic Surgery White Paper October 2005.
        Gastrointest Endosc. 2006; 63: 199-203
        • Rattner D.W.
        • Hawes R.
        • Schwaitzberg S.
        • et al.
        The second SAGES/ASGE white paper on natural orifice transluminal endoscopic surgery: 5 years of progress.
        Surg Endosc. 2011; 25: 2441-2448
        • Inoue H.
        • Minami H.
        • Kobayashi Y.
        • et al.
        Peroral endoscopic myotomy (POEM) for esophageal achalasia.
        Endoscopy. 2010; 42: 265-271
        • Inoue H.
        • Ikeda H.
        • Hosoya T.
        • et al.
        Submucosal endoscopic tumor resection for subepithelial tumors in the esophagus and cardia.
        Endoscopy. 2012; 44: 225-230
        • Khashab M.A.
        • Ngamruengphong S.
        • Carr-Locke D.
        • et al.
        Gastric per-oral endoscopic myotomy for refractory gastroparesis: results from the first multicenter study on endoscopic pyloromyotomy (with video).
        Gastrointest Endosc. 2017; 85: 123-128
        • Yang J.
        • Zeng X.
        • Yuan X.
        • et al.
        An international study on the use of peroral endoscopic myotomy (POEM) in the management of esophageal diverticula: the first multicenter D-POEM experience.
        Endoscopy. 2019; 51: 346-349
        • Liu B.R.
        • Ullah S.
        • Ye L.
        • et al.
        Endoscopic transcecal appendectomy: a novel option for the treatment of appendiceal polyps.
        VideoGIE. 2019; 4: 271-273
        • James B.C.
        • Angelos P.
        • Grogan R.H.
        Transoral endocrine surgery: considerations for adopting a new technique.
        J Surg Oncol. 2020; 122: 36-40

      Linked Article

      • Flexible endoscopic transoral thyroidectomy: a pilot study in a porcine model (with video)
        Gastrointestinal EndoscopyVol. 93Issue 1
        • Preview
          Both endoscopic (laparoscopic) and robotic approaches to minimally invasive thyroidectomy have been developed, but none has gained widespread acceptance.1,2 Laparoscopic surgery requires 3 ports and a large working space. Transoral endoscopic thyroidectomy and hybrid natural orifice transluminal endoscopic surgery (NOTES) with the use of a vestibular approach has had success in producing a scar-free thyroidectomy3,4 but also requires a large working space. Inspired by our pure NOTES experience, we hypothesized that flexible endoscopic thyroidectomy could be done by using a single operating channel and thus obviate the need for hybrid NOTES or laparoscopic instrument-assisted rigid endoscopic operations.
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