Hyperdense middle and anterior cerebral arteries: familiar and not so familiar CT signs of acute ischaemic stroke.

DESCRIPTION We present a case of a 67-year-old patient who attended accident and emergency with left-sided weakness. Background included atrial fibrillation (on long-term warfarin). Examination revealed left hemiparesis, expressive dysphasia and a reduced Glasgow Coma Score, consistent with a right hemisphere cerebral vascular accident. Initial CT head demonstrated a hyperdense right middle cerebral artery (MCA) with extensive right MCA territory infarct and minor mass effect (figure 1). The left anterior cerebral artery (ACA) was also hyperdense, with loss of grey/white matter differentiation within the left ACA vascular territory, suggestive of a further infarct (figure 2). The patient was managed conservatively but unfortunately following further deterioration a repeat CT showed haemorrhagic transformation of the right MCA territory infarct with significant mass effect and transtentorial herniation. There was an evolution of the left ACA territory infarct (figure 3). Neurosurgical intervention was not deemed appropriate and the patient died later that day due to raised intracranial pressure secondary to significant mass effect. The hyperdense MCA sign represents occlusive thrombus within an MCA. It is one of the most well-recognised early signs of ischaemic stroke detectable on non-contrast CT and is associated with a poor prognosis. In contrast, a hyperdense ACA is a less well-recognised sign. This probably relates to the preferential course of emboli into the MCA rather than the ACA and the smaller calibre of the ACA, making detection of occlusive ACA emboli on