Non-contrast CT reveals a diffuse pseudosubarachnoid haemorrhage in the bilateral cerebral hemispheres, causing complete effacement of all ventricles and sulci spaces. Large haematomas are evident in the left frontoparietal and right temporal lobes, accompanied by a diffuse lack of white-grey matter differentiation.
CT angiogram depicts progressive narrowing of the distal cervical, lacerum, and petrous segments of the bilateral internal carotid arteries, with complete occlusion of the distal segments (Bouthillier classification). Additionally, there is occlusion of the proximal foraminal segments (V2) of the bilateral vertebral arteries at the level of C5-C6.
Ring artifacts are observed in both the non-contrast CT and CT angiogram of the brain.
The overall impression suggests bilateral internal carotid and vertebral artery occlusion, likely stemming from severe brain swelling with raised intracranial pressure due to bilateral parenchymal haematoma and global hypoxic-ischaemic encephalopathy.