Fig. 1

Imaging: Head CT (A) revealed multiple soft tissue densities under the scalp in both occipital regions, prominently on the right (red arrow); CE-MRV (B) showed slenderness of bilateral transverse sinus (red arrows) with abnormal vascular mass in the right occipital region (yellow arrow); a scalp AVF fed by the right occipital artery on DSA imaging (C) and abnormal vascular mass in the right occipital region on CTV imaging (D). Physical examination of the occiput after head-shaving revealed scalp swelling on the occipital cranium (E, F) and a small pulsating lump in the occipital scalp (G, red arrow). Ultrasound findings (H): Tortuous vascular mass measuring 9.6 × 8.8 mm, which showed significantly increased blood flow velocity at the proximal of the fistula with a “spicule-like” edge on the blood flow spectrum and mixed-frequency blood flow sound. At the distal end, there was a relative decrease in blood flow velocity and pulsatile index. Blood flow imaging of the deep side of the fistula revealed abnormal blood flow mixing in the intracranial venous sinuses