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Findings: A comminuted fracture of the left posterior bone with minimal distraction is present. A minimally distracted, nondisplaced linear fracture is also seen through the right temporal bone. There is overlying soft tissue swelling as well as an underlying lenticular extra-axial fluid collection containing a fluid-fluid level.
Diagnosis: Multiple skull fractures with an epidural hematoma in the right temporal region.
Discussion: Epidural hematomas usually result from head trauma involving a skull fracture of the temporal bone, most often disrupting the middle meningeal artery. Tears of venous structures such as the middle meningeal vein, venous sinuses, or diploic veins can also produce epidural hematomas. Stretching or tearing of meningeal arteries without a skull fracture can also occur, especially in children. Epidural hematomas exist in the potential space between the dura and the inner table of the skull. They can cross the midline unlike subdural hematomas but cannot cross cranial sutures where the dura is more firmly attached. Most epidural hematomas occur in the temporal parietal region, and approximately half of patients have a lucid interval prior to deterioration.
On CT, epidural hematomas appear as well-defined, high attenuation lenticular or biconvex extra-axial collections. Associated mass effect with sulcal effacement and midline shift is frequently present. Overlying linear skull fractures can often be visualized on bone windows. If an epidural hematoma appears heterogeneous, containing irregular areas of lower attenuation, this can indicate active extravasation of fresh unclotted blood, requiring immediate surgical attention. Alternatively, areas of low attenuation can represent serum extruded from the clot.
References:
Brant and Helms. Fundamentals of Diagnostic Radiology. 1994:54-55.
Grossman and Yousem. Neuroradiology. 1994;151-152.
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