Clinically necessary classification and imaging findings of achalasia

achalasia of cardia (AC) is a primary oesophageal motility disorder that causes dysphagia, reflux, chest pain, and weight loss due to poor lower esophageal sphincter (LES) laxity and lack of esophageal
peristalsis leading to food retention.
The prevalence is approximately 32.
58 per 100,000
.

The main bases for diagnosing achalasia include clinical symptoms, esophageal angiography, esophageal dynamics, and upper gastrointestinal endoscopy, of which high-resolution esophageal manometry (HRM) is the "gold standard"
for diagnosis.

HRM is the "gold standard" for diagnosing AC

The typical presentation of patients with achalasia in esophageal manometry is increased comprehensive relaxation pressure of LES and ineffective peristalsis
of the esophageal body.
The sensitivity of HRM in diagnosing achalasia is higher than that of traditional esophageal manometry methods, which can be as high as 89%~97%.

The procedure is simpler than other diagnostic methods, showing intraluminal pressure in the esophagus, and more accurately reflecting the occurrence of LES laxity disorder and ineffective peristalsis of the esophageal body
.

In order to standardize the interpretation of HRM results and use them in disease diagnosis, the International High Resolution Esophageal Manometry Working Group released the first edition of the classification standard for esophageal motility disorders in 2009 and named it the Chicago classification (CC), CC has become a world-recognized classic classification of HRM.
The latest version 4 of CC was updated in
January 2021.

CC v4.
0 divides achalasia into 3 subtypes, all of which are accompanied by ineffective peristalsis of esophageal smooth muscle and LES flaccid disorder, distinguished by the pattern of esophageal relaxation and contraction

• Type I AC (accounting for 20%~40% of all cases) is defined as LES comprehensive relaxation pressure≥ 15 mmHg (1 mmHg = 0.
  133 kPa) and ineffective peristalsis of the esophageal body;

• Type II AC (the most common, accounting for 50%~70% of all cases) is defined as LES comprehensive relaxation pressure≥ 15 mmHg and ineffective peristalsis of the esophageal body, with 20% or more swallowing activity causing total esophageal hypercompression;

• Type III AC (the least common, 5% of all cases) is defined as LES combined relaxation pressure≥ 15 mmHg and ineffective esophageal peristalsis, with premature contraction
  of 20% or more swallowing activity.
  

Esophageal contrast and gastroscopy are effective adjunctive tests for the diagnosis of AC

Esophageal barium angiography

Esophageal angiography is a common test for diagnosing patients with achalasia to assess esophageal emptying capacity and gastroesophageal junction (EGJ) morphology
.
Esophageography in patients with achalasia typically shows esophageal dilation or distortion, EGJ stenosis is "bird's beak" and barium emptying is poor, and in severe cases, the esophagus can be "S" shaped
.

Figure 1: Esophageal barium angiography shows AC features: "bird's beak" deformity and esophageal dilation (source: Medscape)

Figure 2: Lateral radiographs of barium oesophageal contrast showing esophageal dilation (source: Medscape).

Figure 3: Details of esophageal barium angiography showing typical "beak" deformities distal to the esophagus (Credit: Medscape)

According to the results of the esophageal angiography, the degree of esophageal dilation can be divided into 3 levels:

• Grade I.
  is mild, esophageal diameter <4 cm;
• Grade II.
  is moderate, and the diameter of the esophagus is 4~6 cm;

• Grade III is severe, with an esophagus diameter > 6 cm or an "S" shape, also known as a sigmoid esophagus
  .
  

A normal esophageal contrast does not completely rule out achalasia, especially in the early stages
of the disease.
In this case, esophageal manometry is more diagnostic
.

Upper gastrointestinal endoscopy

The diagnostic value of upper gastrointestinal endoscopy is to exclude swallowing obstruction caused by gastrointestinal strictures or mechanical obstruction of the esophagus, such as reflux esophagitis, esophageal rings, esophageal webbing and esophageal cancer, but it is not highly
sensitive to the diagnosis of AC.
Studies have shown that the true positive rate of AC endoscopic diagnosis is only 50%~60%.

According to the different manifestations of AC endoscopic treatment, Professor Ling Enqiang proposed the endoscopic classification of AC (Ling classification) to guide the selection
of AC endoscopic treatment.

3A: LingII.
b type achalasia endoscopic simulation diagram, the midpoint of the semi-annular structure does not exceed 1/3 of the lumen; 3B: LingII.
c type achalasia endoscopic simulation diagram, the midpoint of the semi-annular structure exceeds 1/3 of the lumen; 3C: Ling I; 3D: Ling II.
a; 3E: Ling II.
b; 3F: Ling II.
c; 3G: Ling III.
l type; 3H: Ling III.
r type; 3I.
: Ling III.
lr type

Fig.
4 Typical image of AC Ling classification (Source: Expert Consensus on the Diagnosis and Treatment of Achalasia in China).

Click to read the Expert Consensus on the Diagnosis and Treatment of Achalasia in China (2020, Beijing)

References:

1.
Super Minimally Invasive Collaboration Group of Digestive Endoscopy Branch of Chinese Medical Association, Endoscopist Branch of Chinese Medical Doctor Association, Digestive Endoscopy Branch of Beijing Medical Association.
Expert consensus on the diagnosis and treatment of achalasia in China (2020, Beijing) [J] .
Chinese Journal of Digestive Endoscopy, 2021, 38(4): 256-275

2.
SamoS, CarlsonDA, GregoryDL, et al.
 Incidence and prevalence of achalasia in central Chicago, 2004-2014, since the widespread use of high-resolution manometry[J].
 Clin Gastroenterol Hepatol, 2017, 15(3):366-373.

3.
LIU Xiaotong, ZHAO Wei, CHEN Xin, et al.
Diagnosis and treatment of achalasia[J] .
Chinese Journal of Internal Medicine, 2022, 61(2): 214-218

4.
 Michael AJ Sawyer.
Achalasia Imaging.
Medscape.