Bold-S Signs on Computed Tomography Angiography Are Sensitive Markers for Diagnosing Subcortical Hemorrhage Due to Dural Arteriovenous Fistulae on Emergent Admission

An optimal treatment strategy for subcortical hematomas caused by dural arteriovenous fistulae (dAVF) is important because of the high rebleeding rate. However, it is very difficult to diagnose that on admission. Therefore, an early sensitive predictive marker for subcortical hemorrhage caused by dAVF is necessary, especially during the first contact on admission. S-shaped dilated vessels around the hematoma (bold-S sign) on computed tomography angiography (CTA) performed during admission could be one such marker. Herein, we evaluated the characteristics of these vessels. Among 273 patients with intracerebral hemorrhage between April 2012 and March 2020, 67 patients with subcortical hematomas who underwent CTA on admission without arteriovenous malformations were included. The patients in the dAVF group (n = 7) showed fewer disturbances in consciousness, milder neurological deficits, and more frequent seizures than patients without dAVF (without dAVF group, n = 60). All patients in the dAVF group had dilated S-shaped vessels (2.59 ± 0.27 mm) around the hematomas, and only 20% of the patients in the without dAVF group had these vessels (1.69 ± 0.22 mm). The ratio of the ipsilateral S-shaped/contralateral largest vessels was 1.80 ± 0.29 in the dAVF group and 1.07 ± 0.16 in the group without dAVF. We called the dilated S-shaped vessels the “bold-S sign,” with a cutoff ratio of 1.5. Bold-S sign findings are novel and help in diagnosing subcortical hematomas caused by dAVF on admission.