Lower cranial nerve palsy due to dissection of the internal carotid artery: CT and MR imaging.

Three patients with unilateral lower cranial nerve palsy underwent contrast enhanced CT and magnetic resonance (MR) imaging for the investigation of possible compressive pathology in the region of the jugular foramen. Computed tomography revealed a mural crescentic hypodensity of the corresponding internal carotid artery (ICA) in two patients and a faulty visualization of the vessel in one. Magnetic resonance revealed a corresponding hyperintense lesion expanding the wall and narrowing the lumen of the cervical ICA on both T1- and T2-weighted images. Dissection of the ICA was confirmed by angiography in all three patients. Among the possible etiologies of lower cranial nerve palsy, a dissecting hematoma of the cervical ICA must be considered, which can be diagnosed by CT and MR.