Cerebral air embolism

Cerebral air embolism is rare but can be fatal. They may be venous or arterial and are often iatrogenic. 

Clinical presentation

Presentation is often varied and non-specific but includes confusion, motor weakness, decreased consciousness, seizure, and loss of vision. 

Pathology

Cerebral air embolism can be within the arterial or venous systems. Air can enter both systems directly or cause paradoxical embolus, with a venous air embolus entering the arterial system via a right-to-left shunt. 

Etiology

• arterial:

  • trauma

  • surgery (especially cardiothoracic/neurosurgery)

  • procedures, e.g. arterial line, lung biopsy

• venous:

  • central venous catheter placement or removal

  • IV contrast injection into a peripheral line

Complications

Cerebral air/gas emboli can act like thrombotic emboli and cause end-artery occlusion and ischemic stroke. Cerebral edema can also develop. 

Radiographic features

The distribution of gas is variable and extensive cerebral infarction, often in a watershed distribution, maybe the only visible change. 

CT

• may only be diagnostic in the acute setting as gas is absorbed rapidly ⁴

• use of lung windows may help increase detection

MRI

MRI is primarily used to evaluate the complications of cerebral air embolism (infarction) rather than to detect the air directly. 

Treatment and prognosis

Treatment is typically supportive although there is increasing evidence for the use of hyperbaric oxygen therapy. 

Differential diagnosis

• pneumocephalus

• fat in dural sinuses