We would like to thank professor Fox for his keen interest in our work, his incisive comments and physiologic clarifications. We do agree that there is a lot of work that will be required to clarify the nature and clinical implications of esophago-gastric junction outflow obstruction (EGJOO).
While motor physiologists are deciphering the manometric features, mechanisms and possible ramifications, clinicians need to know what to do with the information they receive on a high resolution manometric (HRM) report and patients need help with their symptoms. By sub-classifying EGJOO, our study attempts to facilitate clinical decisions that would potentially help both clinicians and patients. For example, in isolated (classic) EGJOO, balloon dilation of the EGJ could be one clinical option, while in a case of EGJOO with diffuse esophageal spasm (DES), botulinum toxin injection of the EGJ and the distal esophagus might be more appropriate and clinically useful. Prospective, multicenter trials performed on better defined manometric phenotypes, such as the ones we proposed in our study, will be essential, but they will also be hampered by the fluidity of the HRM diagnosis that we reported.
The HRM community is looking forward to further fine-tuning of the Chicago classification that will open-mindedly incorporate such concepts and eventually lead to more precise manometric diagnosis and clinically useful interventions.
Triadafilopoulos and Clarke present a retrospective assessment of high-resolution manometry (HRM) in patients with oesophago-gastric junction outlet obstruction (EGJOO; 116/ 478 (24%) consecutive patients).1 Overall, “only” 38% patients had EGJOO (IRP >15mmHg with preserved peristalsis), 12% received a final diagnosis of achalasia and 50% had “elements” of other manometric diagnoses (spasm, hypercontractile or ineffective motility). Based on this data the authors suggest that the current diagnosis of EGJOO requires refinement and a new classification of EGJOO subtypes is proposed.
Similar to the three types of achalasia recognized by the Chicago Classification version 3 (CCv.3),2 the presence or absence of peristaltic abnormalities with EGJOO could indicate different underlying etiology and guide treatment decisions.3, 4 However, as yet, the data presented does not provide sufficient support for this proposal. Patients with EGJOO with and without other coexisting manometric findings were indistinguishable based on clinical characteristics. Further, clearance function assessed by concurrent high-resolution impedance was impaired to a similar extent in all subgroups.
The Chicago Classification is a hierarchical system based on mechanical principles.2 Disorders of EGJ motility and function are prioritized because disorders of motility (e.g. spasm, ineffective motility) have less impact on bolus transport that impaired relaxation or opening of the lower oeso...
The Chicago Classification is a hierarchical system based on mechanical principles.2 Disorders of EGJ motility and function are prioritized because disorders of motility (e.g. spasm, ineffective motility) have less impact on bolus transport that impaired relaxation or opening of the lower oesophageal sphincter (achalasia) and / or impaired opening of the EGJ (outlet obstruction). The Hagen–Poiseuille equation dictates that flow through a tube (here generated by peristaltic contraction) is directly correlated to the first power to bolus pressure, but inversely correlated to the fourth power of the radius of the tube (here the opening between the oesophagus and the stomach).5 This likely explains why there was no significant difference between EGJOO subgroups in terms of bolus clearance.
The lack of correlation of manometric findings with symptoms also requires comment. Whereas patients with achalasia often report symptoms after ingestion of fluids or solids, the majority of those with EGJOO have difficulties only when eating solid food.6 The CCv.3 is based on analysis of ten 5ml water swallows in the supine position. This approach does not represent normal oesophageal function. Adjunctive tests with rapid drink challenge (RDC; 100-200ml water) or a solid test meal improve diagnostic sensitivity for disorders of EGJ motility and function.7-9 This is particularly important in EGJOO because viscous resistance for single water swallows is minimal. Increasing the physiological load by increasing bolus volume or viscosity highlights obstruction to bolus transport. Further, patient reports of symptoms during the HRM test meal study supports the clinical relevance of the EGJOO diagnosis and can guide effective management.10
Technical issues are also important in physiological measurement. The poor test-test reproducibility suggests a lack of specificity or susceptibility to measurement artefacts such as baseline drift. By increasing the signal to noise ratio inclusion of RDC and a test meal in HRM protocols may improve the sub-optimal test-retest reproducibility and inter-observer agreement for this diagnosis reported for water swallows.11, 12 Additionally, the application of new technology to assess EGJ distensibility such as Endo-FLIP may also improve diagnostic sensitivity for EGJOO.13
In summary, publication of this large case series of EGJOO patients is welcome because limited physiological or clinical data exist to inform management in this heterogeneous condition. Triadafilopoulos and Clarke are certainly correct that there are distinct sub-groups within this condition; however, more work is required before a clinically relevant classification system can be introduced.
1. Triadafilopoulos G, Clarke JO. Clinical and manometric characteristics of patients with oesophagogastric outflow obstruction: towards a new classification. BMJ Open Gastroenterol 2018;5:e000210.
2. Kahrilas PJ, Bredenoord AJ, Fox M, et al. The Chicago Classification of esophageal motility disorders, v3.0. Neurogastroenterol Motil 2015;27:160-74.
3. Kahrilas PJ, Boeckxstaens G. The spectrum of achalasia: lessons from studies of pathophysiology and high-resolution manometry. Gastroenterology 2013;145:954-65.
4. Kahrilas PJ, Bredenoord AJ, Fox M, et al. Expert consensus document: Advances in the management of oesophageal motility disorders in the era of high-resolution manometry: a focus on achalasia syndromes. Nat Rev Gastroenterol Hepatol 2017;14:677-688.
5. Pandolfino JE, Ghosh SK, Lodhia N, et al. Utilizing intraluminal pressure gradients to predict esophageal clearance: a validation study. Am J Gastroenterol 2008;103:1898-905.
6. Ang D, Fox M. Achalasia and Esophageal Outlet Obstruction. In: Bardan E, Shaker R, eds. Gastrointestinal Motility Disorders: a point of care clinical guide. New York: Springer International Publishing, 2018:3-23.
7. Ang D, Hollenstein M, Misselwitz B, et al. Rapid Drink Challenge in high-resolution manometry: an adjunctive test for detection of esophageal motility disorders. Neurogastroenterol Motil 2017;29.
8. Ang D, Misselwitz B, Hollenstein M, et al. Diagnostic yield of high-resolution manometry with a solid test meal for clinically relevant, symptomatic oesophageal motility disorders: serial diagnostic study. Lancet Gastroenterol Hepatol 2017;2:654-661.
9. Hollenstein M, Thwaites DT, Buetikofer S, et al. Pharyngeal swallowing and oesophageal motility during a solid meal test: a prospective study in healthy volunteers and patients with major motility disorders. The Lancet Gastroenterology & Hepatology 2017;2:644-653.
10. Wang YT, Tai LF, Yazaki E, et al. Investigation of Dysphagia After Antireflux Surgery by High-resolution Manometry: Impact of Multiple Water Swallows and a Solid Test Meal on Diagnosis, Management, and Clinical Outcome. Clin Gastroenterol Hepatol 2015;13:1575-83.
11. Fox MR, Pandolfino JE, Sweis R, et al. Inter-observer agreement for diagnostic classification of esophageal motility disorders defined in high-resolution manometry. Dis Esophagus 2015;28:711-9.
12. Carlson DA, Ravi K, Kahrilas PJ, et al. Diagnosis of Esophageal Motility Disorders: Esophageal Pressure Topography vs. Conventional Line Tracing. Am J Gastroenterol 2015;110:967-77; quiz 978.
13. Kahrilas PJ, Bredenoord AJ, Carlson DA, et al. Advances in Management of Esophageal Motility Disorders. Clin Gastroenterol Hepatol 2018;16:1692-1700.