Can the sigmoid notch sign be used on cranial computed tomography to differentiate between thrombosis and hypoplasia of the cerebral transverse venous sinus?

Abstract

In patients with headache, the distinction between transverse sinus (TS) atresia/hypoplasia and TS thrombosis in cranial magnetic resonance venography (MRV) may be misleading. In this study, we aimed to distinguish TS thrombosis from atretic or severely hypoplastic TS, with the help of cranial computed tomography (CT). Non-contrast cranial CT scans of 51 patients with no or severely thin signal on MRV were analyzed retrospectively using the bone window. Absence or asymmetry of the sigmoid notches on the CT predicted atretic or severe hypoplastic TS, and symmetry predicted thrombotic TS. Afterwards, it was investigated whether the patient's other imaging findings and confirmed diagnoses matched with the predictions. Of the 51 patients included in the study, 15 were diagnosed with TS thrombosis, and 36 were diagnosed with atretic/hypoplastic TS. All 36 of the congenital atresia/hypoplasia diagnoses were correctly predicted. Thrombosis was predicted correctly in 14 of 15 patients with TS thrombosis. In cranial CT, the symmetry or asymmetry of the sigmoid notch sign was examined, and it was found that the evaluation predicted with 93.3% sensitivity (95% confidence interval (CI): 68.05-99.83) and 100% specificity (95% CI: 90.26-100.00) the distinction between TS thrombosis and atretic/hypoplastic sinus. Symmetry or asymmetry of the sigmoid notch on CT is a reliable method that can be used to differentiate congenital atresia/hypoplasia from the TS thrombosis in patients with very thin or absent TS signal on the cranial MRV.