Cerebral vein thrombosis, with oral contraceptives

Thrombosis in the dural sinuses or cerebral veins is much less common than cerebral arterial thromboembolism. It causes a variety of clinical syndromes, which often do not resemble stroke (Bousser and Ross Russell 1997). While ischemic arterial stroke and cerebral venous thrombosis share some causes (Southwick et al. 1986), others are specific to cerebral venous thrombosis (Table 29.1). A particularly high index of suspicion is required in women on the oral contraceptive pill (Saadatnia and Tajmirriahi 2007) and in the puerperium. In the past, cerebral venous thrombosis was strongly associated with otitis media and mastoiditis, lateral sinus thrombosis or otitic hydrocephalus, but the most common causes are now pregnancy and the puerperium, which cause 5-20% of the cerebral venous thrombosis in the developed world, the oral contraceptive pill, malignancy, dehydration, inflammatory disorders and hereditary coagulation disorders. No cause is found in around 20% of cases. 

To conclude, the epidemiological studies on oral contraceptives and thromboembolism all point to the same direction, i.e. to an increased risk of thromboembolic disease (deep vein thrombosis, pulmonary embolism, cerebral thrombosis, myocardial infarction) in women using oral contraceptives of the combined type. Support can also be obtained from the studies on changes in the fibrinolytic system (see below). For thrombosis with rare localization, e.g. in the mesenteric vessels, epidemiological data are still lacking. It remains to be seen whether the risk of thrombosis is reduced with the new low-dose combinations. 

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