Axial cranial non-contrasted CT scan (A) in a patient with sudden onset left hemiparesis and reduced level of consciousness demonstrates a spontaneous acute right-sided subdural haematoma exerting mass effect with ventricular compression and associated with extensive cortical oedema. The axial reconstruction of a CT angiogram (B) confirms that the cause is a ruptured right bifurcation MCA aneurysm.

Axial non-contrasted CT scans (A–C) demonstrate a haematoma in the right occipital lobe associated with a small right-sided acute subdural haemorrhage. There is compression of the right lateral ventricle and uncal herniation on the right. The sulci are generally effaced. CT angiography performed at the same time (D, axial; E and F—coronal reconstructions) confirm that the cause of the haemorrhage was a vascular malformation, probably a dural arteriovenous fistula with a prominent occipital artery supply. Lateral (G and H) and frontal (I) projections from a right external carotid angiogram confirm the presence of a right-sided arteriovenous dural fistula, supplied by branches of the right occipital and meningeal arteries, draining directly into a dilated cortical vein (almost certainly responsible for the haemorrhage), and then into the right transverse sinus. There is also a supply from dural branches of the right vertebral artery and posterior cerebral …