Very large left sided extradural haematoma which underlies the parietal bone and the occipital bone with fracture diastasis of the left lambdoid suture. The haemorrhage therefore has both supratentorial and infratentorial extension pushing the origin of the tentorium inward. There is marked midline shift to the right and compression of the midbrain due to uncal herniation. Haemorrhage within the markedly effaced and displaced left lateral ventricle. The left cerebellar tonsil descends through the foramen magnum without causing compression of the cervicomedullary junction. Several small left cerebral / basal ganglia intraparenchymal haemorrhages are seen. Swirling low density within the generally hyperdense extradural collection is consistent with ongoing arterial bleeding. A left petrous temporal bone fracture is present, accounting for the locules of intracranial gas within the haematoma.