[Paradoxical brain embolism with a floating deep venous thrombus detected by sonography of lower extremities].

A 68-year-old woman was admitted to our hospital due to brain embolism in the right middle cerebral artery. Patent foramen ovale was detected by transesophageal echocardiogram. The sonogram of the legs revealed a floating thrombus originating from the left posterior tibial vein and extended to the superficial femoral vein. Both right middle lobe and left upper lobe were defected in perfusion scans of lung. She was treated with administration of warfarin potassium and caval filters placed in the inferior vena cava and the azygos vein. Thereafter, she had never experienced brain embolism or pulmonary embolism. A floating deep venous thrombus, which is a high risk of pulmonary embolism, could be observed in patients with paradoxical brain embolism. It was suggested that sonography of veins in the legs is essential for detecting embolic sources of brain infarction, as well as evaluating the risk of pulmonary embolism.