An epidural haematoma occurs when there is a tear in a vascular structure, usually arterial, in the potential space between the dura and the skull. The haematoma strips the dura off the skull vault and appears on CT as a biconvex lesion. There is then rapid deterioration after this point. Surgical evacuation via a craniotomy is necessary and if performed early, before damage to brain structures occurs, can have an excellent outcome. Subdural haematoma Subdural haemorrhage usually occurs due to disruption of bridging veins between the brain and the dura.
Blood can track around the brain and between the leaves of the falx.
The presence of a subdural haematoma is an indication of underlying brain injury, and acute subdurals are associated with a worse outcome than epidural haematomas. On CT the subdural appears as a crescentic extra-axial collection. While surgical evacuation is usually indicated, the underlying brain injury will dictate the subsequent clinical course and functional outcome. Cerebral contusion Parenchymal contusions are a manifestation of direct injury to brain tissue. Contusions appear as bright signals within brain tissue, usually in areas abutting the skull or in areas near the zone of impact.