Persistent falcine sinus: is it really rare?

BACKGROUND AND PURPOSE The falcine sinus has been considered as a rare variation of the venous pathway between the dural layers of the falx cerebri. The purpose of this study was to evaluate the incidence of falcine sinus and its anatomic characteristics by using CTA. MATERIALS AND METHODS A total of 586 consecutive patients were enrolled in this study. A falcine sinus on CTA was defined as a midline venous structure connecting the vein of Galen or the internal sagittal sinus with the superior sagittal sinus. When present, anatomic features of the falcine sinus were evaluated. RESULTS Falcine sinuses were present in 12 patients (2.1%). Only 1 case was associated with a congenital anomaly, a dysplastic tentorium. Eight patients had absent or rudimentary straight sinuses, and 4 patients had normal straight sinuses. CONCLUSIONS In contrast to previous reports, falcine sinuses were not rare in the adult population, and most falcine sinuses were not associated with a congenital anomaly or sinus occlusion. Knowledge and recognition of these falcine sinuses are useful and important during the interpretation of brain CTA.