Aberrant innermost longitudinal muscle bundles at the esophagogastric junction during POEM

Nikolas Eleftheriadis, MD, and colleagues from the Digestive Disease Center at Showa University Northern Yokohama in Japan present this video case of an in vivo observation of aberrant innermost longitudinal muscle bundles in front of the circular muscle layer at the level of esophagogastric junction during peroral endoscopic myotomy (POEM).

In this video case, we demonstrated for the first time in vivo the observation of ectopic longitudinal muscle bundles in front of the esophageal circular muscle layer. This finding appeared in approximately 30% of cases, during POEM for esophageal achalasia and was located at the level of esophagogastric junction (GEJ), the high pressure area responsible for achalasia.

Our finding is important because this anatomic variation is described for the first time in vivo. POEM has opened a new area in esophageal anatomy, because for the first time we can observe in vivo the circular and longitudinal muscle layers of the esophagus and ectopic longitudinal muscle bundles, while one can proceed to selective circular myotomy. Because ectopic longitudinal muscle bundles appeared at the level of the gastroesophageal junction (GEJ), this finding can be used as an objective indicator of approaching the GEJ during POEM, which is not always obvious. Myotomy should be completed at the area of GEJ for a successful outcome. However it is related to more technical difficulties than in other areas of the esophagus and more serious adverse events.

Figure 1

Our finding is interesting for endoscopists aiming to perform successful POEM, because identification of ectopic longitudinal muscle bundles can be used as an objective indicator of approaching the GEJ, which is the most important area for complete myotomy and where the majority of serious adverse events appeared during POEM. Endoscopic myotomy at GEJ is sometimes more difficult than myotomy in the proximal esophagus, and  endoscopists should be more careful when approaching the GEJ and should slow down the myotomy rate. Moreover, one can learn that POEM has opened a new area in medicine and esophageal anatomy can be clearly described in vivo.

The exact role of ectopic longitudinal muscle bundles is not completely known at the moment and this area is under further investigation.

Watch the video here.

The information presented in Endoscopedia reflects the opinions of the authors and does not represent the position of the American Society for Gastrointestinal Endoscopy (ASGE). ASGE expressly disclaims any warranties or guarantees, expressed or implied, and is not liable for damages of any kind in connection with the material, information, or procedures set forth.

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