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Note: This is the first case in a short series of CT images of extra-axial intracranial hemorrhages.

Diagnosis: Extradural Hemorrhage.

Also known as Extradural Hematoma, Epidural Hemorrhage or Epidural Hematoma.

Extradural hemorrhages (EDH) are found in 1% to 4% of all head trauma cases and in about 10% of patients who present with traumatic coma. Fewer than 20% of patients demonstrate the classic presentation of a lucid interval between the initial trauma and subsequent neurological deterioration. Delayed development or enlargement is seen in 10% to 30% of all EDHs and usually occurs within the first 24 to 48 hours. Late hematomas develop in 20% of moderate to severely head-injured patients who do not have signs of cerebral contusions on inital posttrauma CT scan.

A fracture that lacerates the Middle Meningeal artery (MMA) or a dural venous sinus is present in 85-95% of patients with EDH; venous “oozing” or MMA tear without fracture accounts for the remainder. EDHs are located between the skull and dura (actually the periosteum lining the inner surface of the cranial bones). As it frocefully strips the dura away from the inner table of the skull an EDH characteristically assumes a focal biconvex or lentiform shape (see the images in refence #4). EDHs do not cross  the cranial sutures. 95% of EDHs  are unilateral and are located above the tentorium. Posterior fossa EDHs are relatively uncommon but have a higher morbidity and mortality rate than their supratentorial counterparts.

On CT the typical EDH is a biconvex extraaxial mass that displaces the brain away from the calvarium. Two thirds of acute EDHs are uniformly high density; in one third, mised hyperdense and hypodense areas are present and indicate active bleeding. The brain adjacent to most EDHs is severely flattened and displaced. Secondary herniations are very common.

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Axial CT section shows an acute extradural hemorrhage (yellow arrows) in the right parietal region with mass effect on the right cerebral hemisphere.

[Click on the image to open a labelled image in a new window. Do the same for all the images]

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Coronal MPR image shows the right acute extradural hemorrhage (yellow arrows) with mass effect and a small parenchymal hemorrhagic contusion in the left temporal lobe (red arrow) - a contrecoup injury.

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Coronal and sagittal VR images of the acute extradural hemorrhage (yellow arrows) and the left temporal contusion (green arrow in coronal image). Note the coronal suture in the sagittal image (blue arrow). No fractures were seen in the cranial bones.

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References & Further Reading:

1. Diagnostic Neuroradiology: A Text/Atlas by Anne G. Osborn, MD.
2. Epidural Hematoma. eMedicine article by Daniel D Price & Sharon R Wilson [Registration required. Free]
3. CT in Head Trauma - Tutorial by Andrew Downie, from SRS-X, the Scottish Radiological Society’s Educational Resource.
4. EDH - Radiopaedia.org article by Frank Gaillard (I got the idea to post colour VR images after I saw this article. Many thanks Frank).
5. Medpix - Hemorrhagic contusion.
6. MedPix discussion on lucid interval in EDH.

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