Epidural hemoatoma has a higher mortality than a subdural, because obviously this is an ARTERY. And so will be under high pressure- forming that "biconcave" appearence on CT.
The most common site of EDH is the temporoparietal region, where the middle meningeal arteryis lacerated.
CT Findings:* Typical appearance is a biconvex, elliptical, extra-axial fluid collections.
* Acute EDH may contain both a hyperattenuating clot and a swirling lucency (believed to represent a mixture of active bleeding and the serum remaining after previous clot formation).
* Subacute EDH becomes homogeneously hyperattenuating.
* Chronic EDH is at least partly hypoattenuating as the clot undergoes breakdown and resorption.