Backgound and Purpose—The risk of seizure early after the diagnosis of cerebral vein and dural sinus thrombosis (CVT) is not known, and the use of prophylactic antiepileptic (AED) medication in the acute phase of CVT is controversial.

Methods—In a multicenter, prospective, observational study, we analyzed the risk factors for seizures experienced before the diagnosis of CVT was confirmed (presenting seizures) or within the following 2 weeks (early seizures). The risk of occurrence of early seizures was compared in 4 risk strata and related to whether patients received AEDs or not. Criteria for the strata were "presenting seizures" and "supratentorial lesions."

Results—Two hundred forty-five of 624 (39.3%) patients with CVT experienced presenting seizures, and 43 (6.9%) patients had early seizure. In logistic-regression analysis, supratentorial lesion (odds ratio [OR]=4.05, 95% CI=2.74 to 5.95), cortical vein thrombosis (OR=2.31, 95% CI=1.44 to 3.73), sagittal sinus thrombosis (OR=2.18, 95% CI=1.50 to 3.18), and puerperal CVT (OR=2.06, 95% CI=1.19 to 3.55) were associated with presenting seizures, whereas supratentorial lesion (OR=3.09, 95% CI=1.56 to 9.62) and presenting seizures (OR=1.74, 95% CI=0.90 to 3.37) predicted early seizures. The risk of early seizures in patients with supratentorial lesions and presenting seizures was significantly lower when AED prophylaxis was used (1 with seizures in 148 patients with AEDs vs 25 in 47 patients without AEDs; OR=0.006, 95% CI=0.001 to 0.05).

Conclusions—CVT patients with supratentorial lesions had a higher risk for both presenting and early seizures, whereas patients with presenting seizures had a higher risk of recurrent seizures within 2 weeks. Our results support the prescription of AEDs in acute CVT patients with supratentorial lesions who present with seizures.