1. CASE STUDY Chris van Zyl KHC

2. 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

3. CXR

4. Differential  Pneumomediastinum  Pneumothorax  Haemopericardium  Pneumopericardium

5. Mr X  Proceded to insert ICD  Consulted Radiology for heart US No haemopericardium seen  Due to location of wound, proceded to CT chest

6. AXIAL CT CHEST

7. Sag + Axial neck

8. THE SIGNS Pneumomediastinum

9. 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

10. 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

11. 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

12. Potential Sources of Mediastinal Air  Extrathoracic  Head and neck  Intraperitoneum and retroperitoneum  Intrathoracic  Trachea and major bronchi  Esophagus  Lung  Pleural space

13. 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

14. Pneumoprecardium

15. Thymic sail sign

16. Ring around the artery sign, Tubular artery sign

17. Double bronchial wall sign

18. Continuous diaphragm sign

19. Extrapleural sign

20. 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

21. Pneumopericardium

22. Chanllenges and Pitfalls  Subpulmonary pneumo + pneumoperitonium can be difficult to defferentiate from extrapleural air collections  Decubitis view helps

23. 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

24. Major fissure

25. Anterior junction line

26. Challenges and Pitfalls  Mach band effect  Optical illusion  Region of lucency associated with convex structures

27. Chanllenges and Pitfalls  Iatrogenic entities

28. Conclusion  Pneumomediastinum can be a diagnostic challenge  Correct assessment of radiological signs is vital in diagnosis.

29. REFERENCES  Radiographics Jun – Aug 2000  Pneumomediastinum Revisited