The upper esophageal sphincter: no man’s land

The upper esophageal sphincter (UES) may be nicknamed no man’s land. First, digestive surgeons call it by his functional name (UES)—marking territory by including the name esophagus—while ENT surgeons usually call it by his anatomic description (cricopharyngeus)—marking territory by including the name pharyngeal, although the physiologic UES is formed also by other muscles as well as cartilages and bones, as Dr. Belafsky team will elegantly show on their review of the anatomy and physiology of this area (1). Second, digestive surgeons frequently access the UES using the incision they are used to perform to do an esophagectomy, i.e., an oblique incision at the medial border of the sternocleidomastoid muscle while head and neck surgeons preferably opt for a transverse or collar incision. Finally, while ENT surgeons have the tools to anatomically inspect the UES and digestive specialists have the tools to inspect it physiologically, they are rarely interchangeably used. Moreover, the UES is often neglected during esophageal manometry, as Dr. Laurino Neto will show (2). This series reviewed the UES anatomy, physiology, pathophysiology and treatment.

The series starts with the review on the anatomy and physiology by the University of California at Davis (1), followed by the functional assessment of the UES by the team of the Federal University of São Paulo (2). In this last review, Dr Laurino shows that high resolution manometry overcomes most of the technical limitations of conventional manometry that precluded an accurate test of the UES. How the UES is affected by two common esophageal diseases is comprehensively review by Dr. Velanovich and his team from the University of South Florida, for the case of gastroesophageal reflux disease (3) and Dr. Menezes and the group from Londrina for the case of achalasia (4). Finally, the group from Buenos Aires, leaded by Dr Schlottmann (5) critically evaluated the 2 most common treatments for UES dysfunction: cricopharyngeal myotomy and toxin botulinum injection.

The experts, and they are real “connaisseurs” of this subject, that were invited to compose this series certainly brought the UES back to knowledge’s land.

Acknowledgments

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Annals of Esophagus for the series “Upper Esophageal Sphincter”. The article did not undergo external peer review.

Conflicts of Interest: The author has completed the ICMJE uniform disclosure form (available at https://aoe.amegroups.com/article/view/10.21037/aoe-2021-02/coif). The series “Upper Esophageal Sphincter” was commissioned by the editorial office without any funding or sponsorship. FAMH served as the unpaid Guest Editor of the series and serves as an unpaid editorial board member of Annals of Esophagus from September 2020 to August 2022. The author has no other conflicts of interest to declare.

Ethical Statement: The author is accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Ramaswamy AT, Martell P, Azevedo R, et al. The upper esophageal sphincter: anatomy and physiology. Ann Esophagus 2021; [Crossref]
2. Laurino Neto RM, Herbella FAM. A narrative review of current functional assessment of the upper esophageal sphincter. Ann Esophagus 2021; [Crossref]
3. Lippincott M, Velanovich V. The upper esophageal sphincter in gastroesophageal reflux disease. Ann Esophagus 2021; [Crossref]
4. Menezes MA, Valezi AC, Herbella FAM. A narrative review of the function of upper esophageal sphincter in the achalasia. Ann Esophagus 2021; [Crossref]
5. Laxague F, Herbella FAM, Schlottmann F. Cricopharyngeal myotomy and toxin botulinum injection for the treatment of upper esophageal sphincter disorders: a narrative review. Ann Esophagus 2021; [Crossref]

Fernando A. M. Herbella