Extradural hematomas usually present a convex cerebral surface on axial and coronal images. They nearly always contain clotted blood which appears white on CT; a central darker area suggests active bleeding (Fig 1). Subdural hematomas are generally more extensive and of more variable density (Fig 2). Cerebral contusions usually are, or soon become, hemorrhagic and local mass effect increases over the first 2 or 3 days before diminishing ( Fig..3). Isolated intracerebral hematomas can first occur or appear after a few days. Massive intraventricular hemorrhage is rare and is generally seen only in patients with severe head injury, a group with a high mortality. Small amounts of intraventricular blood are common and have no prognostic significance.
Fig. 1 CT of a patient's head after a fall, showing an acute extradural hematoma under the right side of the frontal bone. Areas of low density within it are suggestive of active bleeding.
Fig. 2 CT of a patient's head 6 h after a road traffic accident; the patient is drowsy with a right hemiparesis and hemianopia. A large right subdural hematoma is shown with considerable associated mass effect, resulting in transtentorial coning and a left posterior cerebral artery territory infarct.
Fig. 3 CT of a patient's head after a severe road traffic accident; the Glasgow Coma Score on admission was 9. Bilateral hemorrhagic contusions are present in the temporal and frontal lobes, with obliteration of the basal cisterns. Low density in the brainstem relative to the cerebellum is a poor prognostic sign. The patient's condition deteriorated and he died 3 days later.
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