Fig. 16 Arteriogram and magnetic resonance imaging (MRI) scan of two patients with left spontaneous carotid artery dissections. A. Arteriogram (lateral view, left common carotid injection) shows a tapered narrowing (black arrows) of the left internal carotid artery with slow flow. The abnormal artery segment extends from the C2 level to the base of the skull. (The patient, a 52-year-old woman, initially noted left amaurosis fugax and left upper lid ptosis as well as left eye injection. On examination, she also had facial and tongue weakness). B. (Top) T1-weighted MRI scan TR = 600, TE = 20. A bright signal, denoting blood (white arrow) surrounds a dark signal indicative of flow in the left internal carotid artery. The normal right internal carotid artery is also shown as a flow void (arrowhead). The bright signal anterior to the right carotid denotes fat, which on the T2-weighted images will be much less echo-intense. (Bottom) T2-weighted MRI scan (TR = 2500, TE = 75) shows persistence of the bright signal generated by blood (white arrow) surrounding the left internal carotid artery. The fat density anterior to the right carotid artery, which was bright on the T1-weighted image, has practically disappeared on the T2-weighted scan. (The patient, a 53-year-old man, noted an acute onset, left-sided headache followed by speech and swallowing difficulties. Examination also revealed multiple left cranial neuropathies). Arteriogram and MRI scan courtesy of Richard Latchaw, MD.