Imaging techniques in suspected internal carotid artery dissection.

FIGURE 1. Coronal T2-weighted MRI (TR 1500 ms, TE 80 ms) demonstrating two high-signal areas in the left basal ganglia (arrows). phenomena after ovarian stimulation with human gonadotro-pins. JP: Occlusion de l'artere ce're'brale moyenne lors d'une induction de l'ovulation par les gonadotrophines. To the Editor: The case report by Panisset and Eidelman 1 brought my attention to a consequence of internal carotid artery dissection that I have not previously encountered in my practice, namely, multiple lower cranial nerve pareses. While I appreciate their enlightening me on that process, I must object to the interpretations of normal computed tomography (CT) scans in two of the patients. Figure 5 demonstrates the bull's-eye sign of the narrowed, enhancing true lumen surrounded by hypodense intramural hematoma. It stands out as a virtual negative in contrast to the magnetic resonance image shown on the opposite page. Figure 1 demonstrates a round, probably vascular structure just medial to the right styloid process, which is in the expected location of the right internal carotid artery, but larger than would be expected. The left internal carotid artery is visible on the opposite side and normal in size. Contrast-enhancement effect seems somewhat suboptimal and certainly insufficient to distinguish enhancing true lumen from intramural hematoma. Nevertheless , the dilated structure in the expected position of the internal carotid artery is highly suspicious for carotid dissection. A diagnosis of internal carotid artery dissection can be made on CT, and we have done so multiple times in the past. 2 We are constantly vigilant to examine the cervical internal carotid artery in