Edema is seen in the thalamus, high signal intensity in the hippocampus on DWI (principally T2 shine through), and abnormal enhancement post-contrast in these regions together with the medial occipital lobe (all on the right). CE-MRA reveals the right vertebral artery to be narrowed in its midportion, with a small pseudoaneurysm at the level of transition in vessel caliber, and a crescent of methemoglobin (image not shown) on axial imaging, all consistent with a vertebral artery dissection.

Part of the on-line supplement to Neuroradiology – The Essentials with MR and CT (© 2015)