Commentary

Severe submucosal fibrosis encountered during peroral endoscopic myotomy (POEM), particularly in patients with end-stage achalasia or prior interventions, can significantly increase the risk of adverse events or even impede completion of the procedure. Song et al. [1] should be commended for describing an innovative alternate approach to these select cases. While POEM with dissection through the mediastinum represents an intriguing concept, some considerations deserve further attention. We should recognize that working in the mediastinum may pose new challenges. For one, direct insufflation in the mediastinum may potentially increase the risk of tension pneumoperitoneum, especially when the insufflated carbon dioxide cannot escape into the gastrointestinal lumen, the so-called “one-way valve” phenomenon. Furthermore, as opposed to working within the confines of a submucosal space, dissection in the mediastinum requires us to operate in close proximity to vital structures. Inadvertent injury to these organs or bleeding in the mediastinum can result in severe consequences, given the anatomical unfamiliarity of this space to most endoscopists and our tools that are ill-equipped to manage any potential complications at this level. Lastly, the proposed approach is in many ways similar to a laparoscopic Heller myotomy in which the esophageal myotomy is performed from the mediastinal side. With this strategy, myotomy proceeds from the outer longitudinal muscle towards the inner circular layer. Given the close proximity of the circular muscle layer to the submucosa, particularly if severe fibrosis impedes the separation of these two layers, there is a possible risk of either mucosotomy or incomplete myotomy of the circular muscle, resulting in failed POEM.

In conclusion, POEM through the mediastinum is another example of how we continue to push the boundaries of interventional endoscopy. This may represent a viable alternative for the extremely difficult cases, albeit further investigation is needed. Until then, finding a different submucosal tunnel trajectory during POEM is our best bet before venturing into the mediastinum.

Publication History

Article published online:
29 August 2024

• References

• 1 Song L, Ma L, Wang L. et al. Peroral endoscopic mediastinal tunneling myotomy for esophageal achalasia: the first case treated in mediastinal tunnel. Endoscopy 2024; 56: E400-E401 DOI: 10.1055/a-2308-2823. (PMID: 38759961)