Third space endoscopy: the future of treating gastrointestinal dysmotility

Third space endoscopy (TSE) or submucosal endoscopy provides with the opportunity for minimally invasive management of various gastrointestinal disorders. TSE is a relatively new field and the knowledge on its utility continues to advance. The purpose of this review is to provide with updated evidence on the efficacy and utility of TSE in gastrointestinal motility disorders including achalasia and refractory gastroparesis.

Peroral endoscopic myotomy (POEM) is a safe procedure with emerging evidence on its durability as well. Major technical variations do not appear to impact the outcomes of POEM. Recent randomized trials suggest superiority of POEM over pneumatic dilatation and noninferiority over Heller's myotomy in idiopathic achalasia. With regard to gastric POEM (G-POEM), recent evidence confirms its efficacy in refractory gastroparesis. Although effective, the long-term outcomes of G-POEM are not well known. In addition, the criteria for patient selection remain elusive.

TSE has emerged as a new frontier in the endoscopic management of gastrointestinal motility disorders. While short-term outcomes are encouraging, the durability of TSE remains to be seen in achalasia as well as refractory gastroparesis. Insights regarding patient selection and predictors of outcomes may help optimizing the results of gastric POEM in refractory gastroparesis.