Epidural hematoma is defined as a collection of blood in which location?

• A. A collection of blood in the space between the skull and dura mater
• B. Blood under the dura mater
• C. Blood in the subarachnoid space
• D. Blood within brain tissue

Answer: (A)

The main idea is that an epidural hematoma is a bleed into the space between the skull and the dura mater. This area is a potential space that allows blood to accumulate rapidly after trauma, often from tearing of a meningeal artery, such as after a temporal bone fracture. The result is a discrete, lens-shaped collection that can quickly enlarge and compress the brain, producing a rapid change in consciousness after an initial brief improvement. On imaging, it tends to appear as a biconvex shape and stays confined to the epidural space because the dura is fused to the skull at skull sutures.

In contrast, a subdural hematoma is blood between the dura and the arachnoid mater, usually from venous bleeding and often with a crescent shape that crosses sutures. A subarachnoid hemorrhage involves blood in the subarachnoid space around the brain and is classically associated with a sudden severe (“thunderclap”) headache. Bleeding within the brain tissue itself is an intracerebral hemorrhage, occurring inside the brain parenchyma and commonly related to hypertension or vascular abnormalities.