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

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

AXIAL CT CHEST

Sag + Axial neck

THE SIGNS

Pneumomediastinum

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

Pneumoprecardium

Thymic sail sign

Ring around the artery sign, Tubular artery sign

Double bronchial wall sign

Continuous diaphragm sign

Extrapleural sign

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

Pneumopericardium

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

Major fissure

Anterior junction line

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