Factor V Leiden mutation is a risk factor for cerebral venous thrombosis: a case-control study of 55 patients.

BACKGROUND AND PURPOSE Different coagulation disorders have been associated with cerebral venous thrombosis (CVT). Until now, fewer than 50 patients have been reported with CVT and the factor V Leiden (FVL) mutation. Although the prevalence of FVL-positive patients with CVT ranged from 10% to 25%, it was as low as 0.5% to 3% in the control groups. Most other studies had not systematically searched for concomitant risk factors or previous thromboembolic events. To better define the relevance of the FVL mutation in conjunction with additional risk factors in CVT, we conducted the present case-control study. METHODS Fifty-five patients with CVT were compared with 272 healthy controls. A standardized interview regarding established risk factors for venous thrombosis and the patients' and their families' histories for thromboembolic events was performed. The presence of the FVL mutation was determined by polymerase chain reaction on DNA obtained from peripheral blood leukocytes. RESULTS Of 55 patients, 8 (14.5%) were heterozygous for the FVL mutation compared with 17 of 272 controls (6.25%). The relative risk for the presence of FVL was 2.55 (95% confidence interval, 1.04 to 6.26; P=0.04). Additional risk factors for CVT were frequently found in both the presence and absence of FVL. Recurrence of venous thromboembolic events was more frequent in patients with the FVL mutation (5 of 8 patients, 62.5%) than in those without this anomaly (8 of 47 patients, 17%; P<0.005). CONCLUSIONS Our study confirms the FVL mutation as the most relevant hereditary risk factor for CVT. Coexisting risk factors are usually involved in the initiation of CVT. Patients with the FVL mutation are at an increased risk for recurrent venous thrombosis.