Background: The accidental migration of air from the venous circulation into the systemic arterial circulation is called paradoxical air embolism. This is a potential disastrous complication after diagnostic and surgical procedures. Arthrography has been a useful technique in joint imaging for the past decades. Paradoxical cerebral air embolism is a very rare complication, only a few cases have been reported after arthrography of the hip in children. Here, we describe a patient with progressive encephalopathy after computer tomography (CT) arthrography of the ankle.
Case Report: We describe a 64-year-old male who underwent CT-arthrography of the left ankle, after the intra-articular injection of 20 ml of air he experienced progressive neurologic and hemodynamic deterioration. A brain CT showed a small amount of air in a right frontal sulcus. Hyperbaric oxygen therapy (HBO) was initiated after a delay of 16 hours and resulted in a complete recovery. A transesophageal echocardiography confirmed the presence of a right-left shunt.
Conclusions: This case of paradoxical air embolism with severe neurological manifestations after arthrography of the ankle, emphasizes that air embolism should be considered in all patients with neurologic and/or hemodynamic deterioration after the injection of intra articular air. Furthermore a delay of more then 6 hours is no reason to withhold HBO in these patients.

Keywords: Tomography, X-Ray Computed - adverse effects, Intracranial Embolism - radiography, Embolism, Air - radiography, Arthrography - adverse effects, Ankle Joint - radiography