Cerebral arterial oxygen embolism as a complication of hyperbaric oxygen treatment: a case report.

Cerebral arterial gas embolism (CAGE) is a recognised complication of diving-related barotrauma and of medical procedures whereby gas enters the vascular system. CAGE is a principal indication for hyperbaric oxygen treatment (HBOT). In contrast, CAGE resulting from HBOT itself is exceedingly rare. We describe the case of a 73-year-old man undergoing his first session of HBOT for a chronic lower limb wound, who developed acute focal neurological deficits during decompression. He had no known respiratory disease or smoking history. Immediate assessment demonstrated stable physiology. Initial computed tomography (CT) scan of the brain and neck vessels and perfusion imaging did not show any evidence of thrombus or intravascular gas, and partial neurological recovery occurred over several hours. Subsequent magnetic resonance imaging of the brain demonstrated acute infarction involving the left precentral and postcentral gyri. High-resolution CT chest revealed multiple bilateral thin-walled pulmonary cysts, including a left upper lobe cyst with an air-fluid level consistent with recent barotrauma. A transient broncho-venous fistula allowing arterial oxygen embolisation during decompression was considered the most plausible mechanism. The patient improved with supportive management and was discharged with minimal residuae. This case highlights an exceptionally rare but serious complication of HBOT and underscores the importance of vigilance during decompression and careful consideration of occult pulmonary pathology.