Most common underlying cause of a subdural hematoma?

• A. Rupture of a middle cerebral artery
• B. Traumatic contusion
• C. Tearing of bridging vein between cortex and venous sinus
• D. Aneurysm rupture in circle of Willis

Answer: (C)

Tearing of bridging veins between the cortex and the dural venous sinuses is the typical mechanism behind a subdural hematoma. These veins traverse the subdural space and can be stretched and torn with rapid head movement or brain atrophy, leading to venous bleeding into that space. Because it’s venous and slower than an arterial bleed, the presentation can be delayed and the hematoma may appear acute or evolve into a chronic collection. On imaging, subdural hematomas usually form a crescent shape and can cross suture lines, unlike epidural hematomas which are lens-shaped and stay confined by sutures. The other options involve arterial sources or different injury patterns (arterial rupture, contusion, or subarachnoid hemorrhage) and are not the typical cause of subdural bleeding.