CASE STUDY
Chris van Zyl
KHC
MR X
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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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Pneumomediastinum
Pneumothorax
Haemopericardium
Pneumopericardium
Mr X
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Proceded to insert ICD
Consulted Radiology for heart US
 No haemopericardium seen
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Due to location of wound, proceded to CT chest
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AXIAL CT CHEST
Sag + Axial neck
Pneumomediastinum
THE SIGNS
Introduction
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Can be diagnostic challenge
 Demonstrate radiological findings that are difficult
to differentiate from other disease entities
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Needs good understanding of normal anatomy,
pathophysiology and radiological signs to meet the
challenge
Anatomy
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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
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Tissue plane extending anteriorly from mediastinum
to retroperitoneal space via diaphraghmatic
sternocostal attachment
Continuous along flanks and extends to pelvis
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Communicates with peritonium via periaortic and
peri-esophageal fascial planes
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Air can dissect allong these planes
Potential Sources of Mediastinal Air
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Extrathoracic
 Head
and neck
 Intraperitoneum and retroperitoneum
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Intrathoracic
 Trachea
and major bronchi
 Esophagus
 Lung
 Pleural space
Radiographic Signs of Pneumomediastinum
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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
Pneumoprecardium
Thymic sail sign
Ring around the artery sign, Tubular artery sign
Double bronchial wall sign
Continuous diaphragm sign
Extrapleural sign
Challenges and Pitfalls
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Differentiating pneumomediastinum from medial
pneumothorax
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Pneumopericardium
 Suspect when paricarial sac itself is visualized
 Line formed by pneumopericardium confined to
lenth of pericardial sac
Pneumopericardium
Chanllenges and Pitfalls
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Subpulmonary pneumo + pneumoperitonium can be
difficult to defferentiate from extrapleural air
collections
Decubitis view helps
Challenges and Pitfalls
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Normal anatomic structures can mimic air
within mediastinum
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Anterior junction line
 Imaged
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obliquely or lordotically
Superior aspect of major fissure
 Lordotic
positioning
Major fissure
Anterior junction line
Challenges and Pitfalls
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Mach band effect
 Optical
illusion
 Region of lucency associated with convex structures
Chanllenges and Pitfalls
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Iatrogenic
entities
Conclusion
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Pneumomediastinum can be a diagnostic challenge
Correct assessment of radiological signs is vital in
diagnosis.
REFERENCES
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Radiographics Jun – Aug 2000
 Pneumomediastinum Revisited