Extradural hematoma, subdural hematomas, cerebral contusions and subgaleal hematoma

Non-contrast CT demonstrates a moderate left lateral convexity epidural haematoma, measuring 18 mm in maximal depth, associated with an undisplaced left temporoparietal fracture. Thin smear subdural haematomas are seen overlying the left and right temporal lobes, with further blood seen layering on the tentorium cerebelli on the right. 18 mm haemorrhagic contusion involving the left middle/superior temporal gyrus. Left parieto-occipital subgaleal haematoma.

Mild mass effect principally from the left epidural haematoma causes local sulcal effacement and approximately 4 mm of midline shift to the right. No hydrocephalus. Basal cisterns are within normal limits.

The left parietal bone fracture extends through the region of the pterion into the squamous temporal bone and along the floor of the middle cranial fossa, passing through the foramen spinosum and stopping just short of the internal carotid canal.

A fracture through the anterior maxillary wall and floor of the left orbit is also seen, involving the inferior orbital rim and inferior orbital canal. It extends through the lateral orbital wall with probable diastasis of both the sphenozygomatic and frontozygomatic sutures. 

Extradural haematoma (yellow dotted line) is associated with a linear fracture of the parietal bone (blue arrow). Note how the haematoma is bounded by the coronal suture (yellow arrow). Overlying scalpsubgaleal haematoma (orange dotted line) and a subjacent cerebral contusion ( * ). 

Small bilateral subdural haematomas are also noted (< and >) as well as blood layering on the right side of the tentorium (green arrow) seen as a vague region of increased density (easier to appreciate if coronal reformats were performed). 

Extradural haematomas are best thought of as subperiosteal haematomas, located on the inside of the skull. Dura mater is composed of two layers which are fused everywhere except the dural venous sinuses. The outer (parietal) layer is continuous with the periosteum of the skull bones and as such passes into the sutures. As a result, extradural haematomas do not cross suture lines (but they are able to elevate dural venous sinuses, when not overlying sutures).

ScalpSubgaleal haematoma, subdural haematomas, and cerebral haemorrhagic contusion.

What would the right sided-sided subdural haematoma be evidence of (mechanism of injury)?

Extradural haematoma, subdural haematomas, cerebral contusions and subgaleal haematoma

This case illustrates typical appearances of a significant closed head injury with combination of coup and contrecoup injuriesa coup-contrecoup injury, the largest of which is a left sided-sided extradural haematoma (EDH). 

Extradural haematoma