[Cerebrovascular complications and hereditary protein S deficiency: 2 cases].

Hereditary protein S deficiency (HSPD) is a predisposing factor to recurrent venous thrombosis but is not currently associated with stroke. We report two cases of HSPD revealed by stroke in young adults. The first one was a 36-year-old patient whith a pure motor hemiplegia, who gradually recovered without sequelae. Total and free protein S was decreased (55 and 10%). One of his brothers died from pulmonary embolism at 20 years and a sister had low protein S level without clinical signs. The second case was a 26-year-old patient who had a right hemiplegia with aphasia due to an infarction in middle cerebral artery area. He partially recovered, but the course of the illness was complicated by deep venous thrombosis of the lower limbs and pulmonary embolism. Total and free serum protein S level was severely decreased (25 and 0%). The patient's mother and one of his sisters also had low protein S but never had clinical complications. In both case, dupplex scanning, transcranial doppler, echocardiography, serum antithrombin III and protein C were normal. Cigarette smoking was the only risk factor for arterial disease. These two cases suggest that HSPD must be investigated in young patients with stroke, even in cases of lacunar stroke.