Epidural hematomas are found in 1% to 4% of patients imaged for cranio-cerebral trauma.
The most common cause of EDH is a fracture lacerating the middle meningeal artery or a dural venous sinus.
EDH are located between the skull and the dura and strip the dura away from the inner table of the skull.
EDH may cross dural attachments but not the sutures.
95% of EDH are unilateral and occur above the tentorium.
The temporo-parietal area is the most common site. Only 5% of EDH are bilateral.
On CT scans, the typical EDH is a lentiform, biconvex, epidural mass that displaces the gray-white matter interface away from the calvarium. EDH have uniformly high density ; in one third cases, mixed hyper and hypodense areas are present within the hematoma, indicating active bleeding. The brain adjacent to most EDH is severly flattened and displaced. Secondary herniations are very common complications.
When intra-cranial hematoma is suspected, CT is the best and cheapest method of rapid assessment. MR is not adequate : this technique is less available than CT and the examination typically lasts longer than CT, with a risk of motion artifacts.