Esophageal Dilatation with “Air Esophogram Sign”; Achalasia

PA chest radiograph without (Fig. 1) and with supplied annotations (Fig. 2A) shows an abnormal, predominantly right-sided, vertically oriented, tubular radiolucency projected over the mediastinum, paralleling the trachea that extends from thoracic inlet to hiatus. Note that the lateral borders of this tubular radiolucency project beyond the lateral borders of the normal right and left paratracheal stripes, confirming this lesion is esophageal and not airway-based. The left diaphragm is elevated. Note the absence of gastric fundal air. Lateral chest radiograph (Fig. 2A) (annotated) shows the cranial caudal extent of this vertically oriented radiolucency coursing from the thoracic inlet to the hiatus. Note the anterior displacement of the tracheal air column and the thickened interface between the posterior membranous trachea and the anterior esophageal wall in the retrotracheal triangle. Compare and contrast the annotated PA and lateral chest radiographs with the accompanying coronal and sagittal CT (mediastinal window) MIP images (Fig. 3A-3B; 4A-4B). Unenhanced axial mediastinal (Fig. 5A-C) and lung (Fig. 5D-F) window CT images confirm this tubular lucent lesion is separate from and projects lateral to the airway and is esophageal-based. The esophagus is quite capacious and dilated throughout most of intrathoracic course and has an air-fluid level (Fig. 5B) and contains retained debris (Fig. 5E) posing a potential aspiration risk. (Images courtesy of Narinder Paul, MD, University of Toronto).     Diagnosis: Esophageal Dilatation with “Air Esophogram Sign”; Achalasia

Differential Diagnosis

• Obstructing Esophageal Cancer
• Distal Esophageal Stricture
• Various Esophageal Dysmotility Syndromes
• Chagas Disease
• Neoesophagus following Esophagectomy and Conduit Reconstruction

Discussion

This case nicely illustrates the “air esophogram” sign. This particular radiographic sign is created by a vertically oriented column of air, fluid, or a combination of both in the middle mediastinum from a dilated esophagus. When the esophagus is only or primarily air-filled, differentiation of the pathologically dilated esophagus from a dilated trachea (e.g., Tracheobronchomegaly) can be difficult on a single view chest exam. Identification of the paratracheal stripes in their normal anatomic position in one means of differentiation. Other helpful clues include the absence of gastric fundal air because of difficulty in easy passage of food and air from the esophagus through the hiatus and on into the stomach. The lobulated, thickened lateral borders of this dilated air-containing tube should allow easy differentiation from a medial pneumothorax and pneumomediastinum. Although some may have difficulty differentiating a dilated esophagus from an azygos lobe, recognition of the above findings and knowledge of the normal anatomic course and positioning of the azygos lobe should avoid such diagnostic confusion.

 

Primary or idiopathic achalasia is a disease of the myenteric plexus (Auerbach plexus) of the esophagus in which peristalsis is markedly diminished or even absent. Secondary achalasia may simulate primary disease but is the result of underlying neoplasia.

 

Clinical Findings

Primary or idiopathic achalasia usually has its onset in early adulthood whereas secondary achalasia presents latter in life. Presenting symptoms may include dysphagia, regurgitation, halitosis from stasis or esophageal secretions, aspiration pneumonia, and esophageal candidiasis. Long-standing disease may also be complicated by an increased incidence of squamous cell carcinoma of the distal esophagus.

 

Imaging Findings

Chest Radiography

• Air-filled (“air esophagogram” sign) or fluid-filled tubular structure in the mediastinum  (Fig. 1; 2A; 3A; 4A)
• Progressive esophageal dilatation and distention may obliterate normal mediastinal lines, stripes, and interfaces (e.g. azygos esophageal recess; inferior hilar window; retrocardiac clears space; retrotracheal triangle; etc) esophagogram” sign) or fluid-filled tubular structure in the mediastinum  (Fig. 1; 2A; 3A; 4A)
• Small or absent gastric fundus air  (Fig. 1; 2A; 3A; 4A)
• Anterior displacement and bowing of tracheal air column (Fig. 2B; 4A)
• Foci or air space disease, consolidation, basilar bronchiectasis (e.g., aspiration pneumonia; recurrent bouts of aspiration)

Esophography

• Disordered peristalsis; early in disease
• Diminished or absent peristalsis; latter in disease
• Dilution of barium contrast by retained esophageal secretions
• Distended or dilated esophagus
• +/- Megaesophagus
• Distal esophagus demonstrates a smooth, tapered narrowing caused by the contracted esophageal sphincter (“bird-beak” or “rat-tail” sign)
• Gravity may partial overcome the decreased peristalsis and tightened sphincter allowing intermittent passage of small amounts of contrast media when patient is upright
• Little contrast passes through distal esophagus when patient is supine

CT

• Air and or fluid-filled dilated esophagus
• Retained secretions and or debris in the dilated esophagus
• Areas of dependent lung air-space disease manifest as ground-glass opacities and or frank consolidations
• Air-space consolidations may contain regions of fatty attenuation (e.g. lipoid pneumonia)

Treatment

• Pneumatic dilatation
• Surgical myotomy

Selected Readings

1. Mueller CF, Klecker RJ, King MA. Case 3. AJR 2000; 175: 867; 870-871.
2. Parker MS, Rosado de-Christenson ML, Abbott GF. Achalasia. In: Teaching Atlas of Chest Imaging 2006; Thieme, New York: 691-694.
3. Woodfield CA, Levine MS, Rubesin SE, Langlotz CP, Laufer I. Diagnosis of primary versus secondary achalasia: reassessment of clinical and radiographic criteria. AJR 2000; 175: 727-731.
4. VCU Health System Cardiothoracic Pulmonary Imaging - Correlation Conference Case of the Week April 29-May 6, 2010 http://www.vcuthoracicimaging.com/Historyanswer.aspx?qid=45&fid=1

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