What shape does an epidural hematoma typically present on a CT scan?

• A. Wide lens shape
• B. Narrow crescent shape
• C. Flat disc shape
• D. Irregular shape

Answer: (A)

An epidural hematoma typically presents as a biconvex, or lens-shaped, area of hyperdensity on a CT scan. This distinctive shape arises because the blood collects between the skull and the dura mater, pushing the dura away from the skull, creating a convex appearance. The nature of the epidural hematoma, often due to arterial bleeding following a skull fracture, contributes to this well-defined, wide lens shape, which does not cross suture lines due to the attachments of the dura to the skull.

The other shapes mentioned do not accurately describe how an epidural hematoma appears. A narrow crescent shape is characteristic of a subdural hematoma, where the blood collects between the dura mater and the arachnoid membrane, wrapping around the convexities of the brain. A flat disc shape does not typically correlate with hematomas since they usually present with more defined contouring due to their location and the pressure effects on surrounding structures. An irregular shape might suggest a more complex pathology, such as lacerations or other types of bleeding situations, but does not apply to the classic presentation of an epidural hematoma.