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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. CXR. Differential.
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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