[Formation of postoperative hematoma directly under a silastic dural substitute]

Several cases of spontaneous hematoma formation occurred under the Silastic dural substitute were reported with CT-scan and recraniotomy findings. In overall analysis, an incidence of the spontaneous hematoma formation was 35.1% in cases of artificial dural grafting with Silastic sheeting and none with autogenous temporal fascia. On CT-scan the hematoma showed localized high density area severely convex toward underlying brain. At recraniotomy, the hematoma consisted of massive clot presented locally beneath the dural substitute. As it depressed sharply underlying brain, it tends to having shown heavy clinical symptoms in comparison with a volume of clot. Neomembrane formed under the artificial graft seemed the most probable bleeding source.