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Cerebral venous thrombosis (CVT) is a rare condition accounting for 0.5% of all strokes. A multitude of risk factors have been associated with CVT, including coagulation disorders, infections, and use of certain drugs (particularly oral contraceptives). In the International Study on Cerebral Vein and Dural Sinus Thrombosis (ISCVT), a multicenter prospective cohort study of 624 adults with CVT, 44% of patients had more than one cause or predisposing factor. Anemia, first reported as a risk factor in the 19th century, has been linked to CVT in recent case series. In the current study, the authors examined potential risk factors and laboratory profiles in 121 prospectively recruited patients with noninfectious causes of CVT and 120 healthy age- and sex-matched controls.
Severe anemia (hemoglobin <9 g/dL) was more common in patients with CVT than in controls (14 vs. 2 patients; P=0.005), and was independently associated with CVT in multivariate analyses (odds ratio, 1.10; P<0.05). Most patients with severe anemia were female (n=15; 94%). CVT was also associated with hypercholesterolemia, thrombophilia, pregnancy, and puerperium. The association between CVT and severe anemia remained significant even when the analysis excluded the 24 patients with CVT related to pregnancy, puerperium, cancer, or collagen vascular disease.
Stolz E et al. Anemia as a risk factor for cerebral venous thrombosis? An old hypothesis revisited: Results of a prospective study. J Neurol 2007 Jun; 254:729.
Comment
These results suggest that severe anemia is an independent risk factor for CVT. Overall, these findings are in line with those of ISCVT, which found that 9.2% of CVT patients had anemia. Thrombophilia, pregnancy, and puerperium were also common risk factors in ISCVT. However, because CVT is typically multifactorial, clinicians who identify a single risk factor (or even a cause) in a particular patient with CVT should not be deterred from looking for other risk factors.