Low-oestrogen oral contraceptives as a major risk factor for cerebral venous and sinus thrombosis: evidence from a clinical series

Cerebral venous and sinus thrombosis (CVST) is still considered a severe cl inical problem that is difficult to diagnose and manage and is linked to a poor prognosis. Nonetheless, conventional cerebral angiography and magnetic resonance imaging (MRI), or more recently, MR angiography allow a more rap id and precise diagnosis, and prognosis has improved with the use of antico agulant treatment. We report 23 cases of CVST consecutively admitted to the Institute of Neuro logy of the University of Parma during the period 1990-1997. In all cases d iagnosis was confirmed by means of MRI or conventional angiography of brain vessels. Among the patients, 22 were female and 1 was male. In all patient s, plasma levels of protein C, protein S, antithrombin III (ATIII) and anti phospholipid antibodies (APA) were evaluated. In 15 of 23 patients, the pre sence of factor V Leiden mutation was also determined, and found positive i n 3 patients (20%). Of the 22 female patients, 15 (68%) were on low-oestrog en (containing less than 50 mu g oestrogen) oral contraceptive (OC) treatme nt. This percentage of OC use by patients with CVST is much higher than tha t of the rest of the female Italian population. OC use was associated with the presence of factor V Leiden mutation in two cases, with a deficiency of protein C in 1 case and a deficiency of protein S in another. Whether low-oestrogen OCs may induce cerebral thromboembolic events is an o pen matter. According to our data, it may be argued that OCs, even if at lo w oestrogen content, represent a major risk factor for CVST. The use of OCs , as is the case for systemic venous thromboembolic events, may further inc rease the risk of CVST in women carrying the factor V Leiden mutation or ot her inherited hyperthrombotic conditions.