A 67-year-old male patient who presented with sudden-onset headache, blurred vision, and a reduced level of consciousness. Axial CT scan showing hypoattenuation of the cortical and subcortical regions, involving the medial temporal and occipital lobes, as well as the mesencephalon and cerebellum. Note the hyperdense artery sign, consistent with acute thrombosis, in the basilar artery (arrow).