Which condition is a collection of blood between the dura mater and arachnoid mater?

• A. Concussion
• B. Subdural hematoma
• C. Epidural hematoma
• D. Brain herniation

Answer: (B)

Subdural hematoma is a collection of blood between the dura mater and arachnoid mater. It usually results from tearing of bridging veins after head trauma, and because venous bleeding is slower, the bleed can accumulate gradually, with symptoms developing hours to days later. On imaging, it often appears as a crescent-shaped collection that can cross cranial sutures but remains under the dura.

This differs from an epidural hematoma, which occurs between the skull and dura and is typically caused by an arterial bleed; it often presents with a brief loss of consciousness followed by a lucid interval and rapid deterioration, and on imaging looks lens-shaped. Concussion is a functional injury without a visible hematoma, and brain herniation describes a dangerous displacement of brain tissue due to severe pressure, not a localized collection in the space between the dura and arachnoid.