The Chicago Classification of Motility Disorders

An Update

Sabine Roman, MD, PhDa, C. Prakash Gyawali, MD, MRCPb, Yinglian Xiao, MD, PhDc, John E. Pandolfino, MD, MScid and Peter J. Kahrilas, MDd*p-kahrilas@northwestern.edu,     aDigestive Physiology, Hôpital E Herriot, Hospices Civils de Lyon, Claude Bernard Lyon I University, Pavillon H, 5 Place d'Arsonval, Cedex 03, Lyon F-69437, France; bDivision of Gastroenterology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8124, St Louis, MO 63110, USA; cDepartment of Gastroenterology and Hepatology, The First Affiliated Hospital, Sun Yat-sen University, 58 Zhongshan Road 2, Guangzhou 510080, China; dDepartment of Medicine, Feinberg School of Medicine, Northwestern University, 676 St Clair Street, 14th Floor, Chicago, IL 60611-2951, USA

*Corresponding author.

The Chicago Classification defines esophageal motility disorders in high resolution manometry. This is based on individual scoring of 10 swallows performed in supine position. Disorders of esophago-gastric junction (EGJ) outflow obstruction are defined by a median integrated relaxation pressure above the limit of normal and divided into 3 achalasia subtypes and EGJ outflow obstruction. Major motility disorders (aperistalsis, distal esophageal spasm, and hypercontractile esophagus) are patterns not encountered in controls in the context of normal EGJ relaxation. Finally with the latest version of the Chicago Classification, only two minor motor disorders are considered: ineffective esophageal motility and fragmented peristalsis.

Keywords

Esophageal high-resolution manometry

Achalasia

Esophagogastric junction outflow obstruction

Aperistalsis

Distal esophageal spasm

Hypercontractile esophagus

Ineffective esophageal motility

Key points

 The Chicago Classification of esophageal motility disorders is based on a clinical study comprising 10 test swallows performed in a supine posture.

 Esophageal motility disorders are divided into disorders with esophagogastric junction outflow obstruction, major disorders not encountered in normal subjects, and minor motility disorders defined by statistical abnormalities.

 Three subtypes of achalasia are defined that are clinically distinct in terms of responsiveness to therapeutic intervention.

 Major esophageal motility disorders are aperistalsis, distal esophageal spasm, and hypercontractile (jackhammer) esophagus.

 Ineffective esophageal motility is likely to replace weak peristalsis and frequent peristalsis in version 3.0 of the Chicago Classification.

Introduction

High-resolution manometry (HRM) is the current gold standard technique to assess esophageal motility. It uses closely spaced pressure sensors to create a dynamic representation of pressure change along the entire length of the esophagus. Data acquisition is easier than with conventional manometry and interpretation is facilitated by esophageal pressure topography (Clouse) plots.1

Along with the technological innovation, an international consensus process has evolved over recent years to define esophageal motility disorders using HRM, Clouse plots, and standardized metrics. This classification, titled the Chicago Classification, was firstly published in 20092 and was subsequently updated in 2012.3 It was intended to be applied to HRM studies performed in a supine position with 5-mL water swallows and for patients without previous esophagogastric surgery. The 2012 version of the Chicago Classification focused entirely on redefining esophageal motor disorders associated with dysphagia in HRM terms; it did not provide guidance on the assessment of the esophagogastric junction (EGJ) at rest or upper esophageal sphincter (UES) function. Since that publication, substantial further research has been presented and published, intended to improve the diagnostic accuracy and clinical utility of the Chicago Classification. In recognition of this, the international HRM Working Group met in Chicago in May 2014 in conjunction with Digestive Disease Week to discuss these new data in the context of working toward an update of the Chicago Classification (v3.0). This article presents a brief summary of these discussions and proposals to work toward the Chicago Classification 3.0; a process due to be completed in early 2015.

Metrics and swallow pattern characterization

The Chicago Classification is based on scoring of 10 5-mL water swallows performed in supine position. EGJ relaxation, esophageal contractile activity, and esophageal pressurization are evaluated for each swallow. However, a major indication for manometric studies is in the evaluation of patients for potential antireflux surgery and some description of EGJ morphology and quantification of contractility is desirable. Hence, the incorporation of simple metrics relevant to these aspects of motility will be incorporated into Chicago Classification v3.0. Proposed metrics under discussion include mean inspiratory pressure, mean expiratory pressure, the extent and variability of the separation between the lower esophageal sphincter (LES) and crural diaphragm (CD separation), and the EGJ contractile integral (CI), all of which have been used in publications. However, discrepancies exist in the details of calculation methodology for these metrics, the strength of data supporting their utility, and their normative ranges among HRM devices,4-11 all of which are important limitations meriting further consideration.

Esophagogastric Junction Morphology and Deglutitive Relaxation

With HRM and Clouse plots, the relative localization of the 2 constituents of the EGJ, the LES and the CD, define EGJ morphologic subtypes.12 This feature of EGJ morphology is fundamental, and is likely pertinent to its functional integrity. With type I EGJ morphology, there is complete overlap of the CD and LES with no spatial separation evident on the Clouse plot (Fig. 1) and no double peak on the associated spatial pressure variation plot. With type II EGJ morphology, the LES and CD are separated (double-peaked spatial pressure variation plot), but the nadir pressure between the 2 peaks does not decline to gastric pressure; the separation between the pressure peaks is less than 3 cm. With type III EGJ morphology, the LES and CD are clearly separated as shown by a double-peaked spatial pressure variation plot and a nadir pressure between the peaks equal to or less than gastric pressure; with type IIIa the pressure inversion point remains at the CD level, whereas in type IIIb it is located at the LES level. However, the separation between LES and CD may fluctuate in the course of the study and in those instances this should be reported as a range.13 Hence in reporting the LES-CD, the range of observed LES-CD separation observed throughout the study is reported for types II and III EGJ morphology.

Fig. 1 EGJ morphology subtypes. For each panel the instantaneous spatial pressure variation plot corresponding with the red line on the pressure topography plot is shown by the black line on the right. The 2 main EGJ components are the LES and the CD, which cannot be independently quantified when they are superimposed, as with a type I EGJ (A). The respiratory inversion point (RIP), shown by the horizontal dashed line, is at the proximal margin of the EGJ. During inspiration (I), EGJ pressure increases, whereas it decreases during expiration (E). Type II EGJ pressure morphology is shown in (B). Note the 2 peaks on the instantaneous spatial pressure variation plot; the nadir pressure between the peaks is greater than the intragastric pressure. (C, D) Type III EGJ pressure morphology defined as the presence of 2 peaks of the instantaneous spatial pressure variation plot with a nadir pressure between the peaks equal to or less than intragastric pressure. The RIP is proximal to the CD with type IIIa (C), whereas it is proximal to the LES in IIIb (D).

The simplest measurement of baseline EGJ pressure is an average pressure for 3 normal respiratory cycles, ideally in a quiescent portion of the recording, remote from either spontaneous or test swallows in order to exclude the effect of the postdeglutitive contraction. The inspiratory EGJ pressure is the mean maximal inspiratory EGJ pressure and the expiratory EGJ pressure is the average EGJ pressure midway between inspirations. Normative values are reported in Table 1.

Table 1

Reported normal ranges of basal EGJ pressures for control subjects in a supine position among studies and among manometric devices

Pandolfino et al,2 2009 Given Imaging 75 Mean (±2 SD) = 18...