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This case study explores the diagnostic challenges in identifying pneumomediastinum through radiological findings, requiring a profound understanding of anatomy and imaging signs. The text provides insights into differentiating pneumomediastinum from other disease entities and outlines potential pitfalls. It emphasizes the importance of recognizing key radiographic signs for accurate diagnosis.
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CASE STUDY Chris van Zyl KHC
MR X • 21 Year old male • Stab wound L parasternally, 3 ICS (sucking wound) • Surgical emphysema extending to neck • Haemodynamically stable, • no signs of tamponade / vascular injury • Mild resp distress, clinically no pneumothorax
Differential • Pneumomediastinum • Pneumothorax • Haemopericardium • Pneumopericardium
Mr X • Proceded to insert ICD • Consulted Radiology for heart US • No haemopericardium seen • Due to location of wound, proceded to CT chest
Pneumomediastinum THE SIGNS
Introduction • Can be diagnostic challenge • Demonstrate radiological findings that are difficult to differentiate from other disease entities • Needs good understanding of normal anatomy, pathophysiology and radiological signs to meet the challenge
Anatomy • Tissues and organs separating two pleural sacs • Between sternum and vertebral column • Extending from thoracic inlet and diaphragm • Communicates with: • Submandibular space • Retropharyngeal space • Vascular sheaths of the neck
Anatomy • Tissue plane extending anteriorly from mediastinum to retroperitoneal space via diaphraghmatic sternocostal attachment • Continuous along flanks and extends to pelvis • Communicates with peritonium via periaortic and peri-esophageal fascial planes • Air can dissect allong these planes
Potential Sources of Mediastinal Air • Extrathoracic • Head and neck • Intraperitoneum and retroperitoneum • Intrathoracic • Trachea and major bronchi • Esophagus • Lung • Pleural space
Radiographic Signs of Pneumomediastinum • Subcutaneous emphysema • Thymic sail sign • Pneumoprecordium • Ring around the artery sign • Tubular artery sign • Double bronchial wall sign • Continuous diaphragm sign • Extrapleural sign • Air in the pulmonary ligament
Challenges and Pitfalls • Differentiating pneumomediastinum from medial pneumothorax • Pneumopericardium • Suspect when paricarial sac itself is visualized • Line formed by pneumopericardium confined to lenth of pericardial sac
Chanllenges and Pitfalls • Subpulmonary pneumo + pneumoperitonium can be difficult to defferentiate from extrapleural air collections • Decubitis view helps
Challenges and Pitfalls • Normal anatomic structures can mimic air within mediastinum • Anterior junction line • Imaged obliquely or lordotically • Superior aspect of major fissure • Lordotic positioning
Challenges and Pitfalls • Mach band effect • Optical illusion • Region of lucency associated with convex structures
Chanllenges and Pitfalls • Iatrogenic entities
Conclusion • Pneumomediastinum can be a diagnostic challenge • Correct assessment of radiological signs is vital in diagnosis.
REFERENCES • Radiographics Jun – Aug 2000 • Pneumomediastinum Revisited