Chicago Classification v4.0 Update

The **Chicago Classification v4.0 (CCv4.0)** is the latest update in the diagnostic framework for interpreting **high-resolution esophageal manometry (HRM)**, a tool used to evaluate esophageal motility disorders. This version introduces stricter diagnostic criteria, prioritizes clinical relevance, and incorporates adjunctive testing to improve diagnostic accuracy and reduce overdiagnosis of functional abnormalities. Below is a detailed breakdown of the key updates, diagnostic hierarchy, and clinical integration in CCv4.0.

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### **Key Updates in Chicago v4.0 Compared to v3.0**

CCv4.0 introduces several refinements to enhance diagnostic precision and clinical applicability. These updates include:

| **Aspect** | **v3.0** | **v4.0 (Updated)** |

|--------------------------------|-------------------------------------------|-----------------------------------------------------------------------------------|

| **EGJ Outflow Obstruction (EGJOO)** | Elevated IRP with intact peristalsis | Must show **elevated IRP in both supine and upright positions** + abnormal confirmatory test |

| **Achalasia Subtypes** | Based on supine HRM only | Requires **symptom correlation** + supportive testing (e.g., timed barium esophagogram or EndoFLIP) |

| **Distal Esophageal Spasm (DES) / Jackhammer** | Diagnosed solely on manometric features | Requires **clinical symptoms** + exclusion of mechanical obstruction |

| **Position Testing** | Supine only | **Mandatory supine + upright swallows** |

| **Supportive Tests** | Optional | **Recommended**: Timed barium esophagogram, EndoFLIP, or impedance testing |

| **“Clinically Inconclusive” Category** | Not defined | Introduced to avoid overdiagnosis of minor or transient abnormalities |

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### **Diagnostic Hierarchy in CCv4.0**

Esophageal motility disorders are classified into three hierarchical categories. Each diagnosis requires **manometric evidence** and **clinical correlation** (e.g., symptoms such as dysphagia or non-cardiac chest pain) to ensure clinical relevance.

#### **I. Disorders of EGJ Outflow**

These disorders are characterized by **impaired relaxation of the esophagogastric junction (EGJ)**, as indicated by an **elevated integrated relaxation pressure (IRP)**.

1. **Achalasia (Types I–III)**

Defined by **impaired EGJ relaxation (elevated IRP)** and **absent normal peristalsis**. Subtypes are based on manometric features:

• **Type I (Classic Achalasia):**
• **Manometric Features:** Elevated IRP, 100% failed peristalsis, no pressurization.
• **Pathophysiology:** Aperistalsis with advanced neuronal loss.
• **Type II (Achalasia with Panesophageal Pressurization):**
• **Manometric Features:** Elevated IRP, panesophageal pressurization in ≥20% of swallows.
• **Remarks:** Best response to pneumatic dilation or Heller’s myotomy.
• **Type III (Spastic Achalasia):**
• **Manometric Features:** Elevated IRP, premature distal contractions (**distal latency [DL] <4.5 s**) in ≥20% of swallows.
• **Remarks:** Spastic variant; responds best to POEM (Peroral Endoscopic Myotomy).

**Note:** Diagnosis of achalasia requires **symptom correlation** (e.g., dysphagia or regurgitation) and supportive evidence from **timed barium esophagogram** or **EndoFLIP**.

2. **EGJ Outflow Obstruction (EGJOO)**

• **Features:** Elevated median IRP (supine and upright), preserved peristalsis, and absence of panesophageal pressurization.
• **Clinical Relevance:** Treated as a **clinically inconclusive pattern** unless corroborated by symptoms (e.g., dysphagia) and supportive testing (e.g., impaired barium emptying or EGJ distensibility).
• **Etiologies:** Early achalasia, mechanical obstruction (e.g., hiatus hernia, tumor, stricture), opioid use, or transient functional obstruction.

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#### **II. Major Disorders of Peristalsis**

These disorders involve **abnormal peristaltic patterns** that are **clinically relevant** and **distinctive on manometry**.

1. **Distal Esophageal Spasm (DES):**

• **Criteria:** ≥20% premature contractions (**DL <4.5 s**) with normal IRP.
• **Symptoms:** Intermittent dysphagia, chest pain.
• **Clinical Note:** May progress to Type III achalasia.

2. **Hypercontractile Esophagus (“Jackhammer”):**

• **Criteria:** ≥20% swallows with **distal contractile integral (DCI) ≥8,000 mmHg·s·cm** and normal IRP.
• **Symptoms:** Chest pain, dysphagia.
• **Etiology:** Often due to esophageal hyperexcitability or reflux sensitization.

3. **Absent Contractility:**

• **Criteria:** 100% failed peristalsis (**DCI <100 mmHg·s·cm**) with normal IRP.
• **Clinical Context:** Common in systemic sclerosis or severe GERD; associated with risks of aspiration and reflux.

**Note:** CCv4.0 requires **symptom correlation** (e.g., dysphagia or chest pain) for diagnosing DES and hypercontractile esophagus.

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#### **III. Minor Disorders of Peristalsis**

These disorders may impair bolus clearance but have **limited diagnostic specificity**.

1. **Ineffective Esophageal Motility (IEM):**

• **Criteria:** >70% ineffective swallows (**DCI <450 mmHg·s·cm**) or ≥50% failed peristalsis.
• **Clinical Context:** May occur with GERD or diabetes; assess reflux correlation and bolus transit.

2. **Fragmented Peristalsis:**

• **Criteria:** ≥50% swallows with large breaks (>5 cm) in the **20 mmHg isobaric contour**, with preserved contraction vigor (**DCI >450 mmHg·s·cm**).
• **Clinical Context:** Usually of limited clinical significance.

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#### **IV. Normal Motility**

A diagnosis of **normal esophageal motility** is made when:

• **Median IRP** is within the normal range (supine and upright).
• ≥80% of swallows exhibit **normal peristalsis** with complete lower esophageal sphincter (LES) relaxation.

This finding excludes a **major motility disorder**.

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### **Clinical Integration of CCv4.0**

CCv4.0 emphasizes that **HRM findings must not be interpreted in isolation**. Accurate diagnosis requires integration of:

1. **Clinical Symptoms:**

• Dysphagia, regurgitation, chest pain, or other relevant complaints.

2. **Supportive Testing:**

• Timed barium esophagogram (to assess esophageal emptying).
• EndoFLIP (to evaluate EGJ distensibility).
• Impedance testing (to assess bolus transit or reflux).

3. **Exclusion of Secondary Causes:**

• Rule out mechanical obstruction (e.g., tumor, stricture, hiatus hernia).
• Consider prior surgeries, medications (e.g., opioids), or systemic diseases (e.g., scleroderma).

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### **Clinical Implications**

The refinements in CCv4.0 enhance diagnostic precision and guide personalized treatment strategies, such as:

• **Pharmacologic Therapy:** For hypercontractile disorders or reflux-associated symptoms.
• **Endoscopic Interventions:** POEM, pneumatic dilation, or botulinum toxin for achalasia.
• **Surgical Options:** Heller’s myotomy or fundoplication for refractory cases.

By integrating manometric findings with clinical and supportive data, CCv4.0 provides a robust framework for diagnosing and managing esophageal motility disorders effectively.