III. Brain Traumatic Lesions
B. Contusions (areas of hemorrhagic necrosis) (cont)
3. Pathology: In the most typical form of contusion, the summit of a cerebral gyrus is smashed, and the lesion has a wedge shape with its base toward the pia and the apex toward the white matter. All layers of cortex are regularly affected. In its early stage the hemorrhage remains bright red, and the surrounding brain tissue is edematous. When the lesion is older it becomes brick-red and finally golden orange-brown (due to deposition of hemosiderin), with a floor of glial tissue, covered by leptomeningeal fibrosis. The most chronic stage is sometimes called plaque jaune. Dura-arachnoidal adhesions (meningocerebral cicatrix) later form on the surface, and frequently cause post-traumatic epilepsy.