CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the initial evaluation of multiple lower CN palsies. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the initial evaluation of multiple lower CN palsies. CT Neck Multiple different jugular foramen syndromes can result in variable patterns of CN palsies affecting CN IX through CN XII. Lesions involving the jugular foramen can extend caudally in the neck to involve the carotid space. CT is complementary to MRI in assessing jugular foramen lesions or for evaluating for carotid space lesions. Thin-cut high-resolution bone algorithm windows are useful to delineate skull base fractures, hyperostosis, skull base erosion, intratumoral calcification, and the bony margins of the jugular foramen and nearby skull base foramina [144-148]. Contrast should be administered. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CTA Head and Neck Most brainstem syndromes are due to brainstem infarctions and hemorrhages, which are best imaged with MRI [132]. CTA may be complementary to CT or MRI to characterize the vasculature in these clinical scenarios. Cranial Neuropathy When dissection of the internal carotid artery is clinically suspected as a cause of multiple lower CN palsies, CTA may be useful to evaluate for dissection, particularly in the emergent setting. In a study comparing CTA with conventional angiography, CTA had a sensitivity of 66% when evaluating for blunt carotid vascular injury, with most false-negatives representing low grade injuries [190]. In a comparative study, multidetector CT/CTA demonstrated more features of cervical artery (internal carotid and vertebral arteries) dissection compared with MRI/MRA. There was no significant reader preference for MRI/MRA compared with CT/CTA when evaluating for internal carotid artery dissection. MRI/MRA provided additional characterization of ischemic complications [191].
Cranial Neuropathy. CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the initial evaluation of multiple lower CN palsies. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the initial evaluation of multiple lower CN palsies. CT Neck Multiple different jugular foramen syndromes can result in variable patterns of CN palsies affecting CN IX through CN XII. Lesions involving the jugular foramen can extend caudally in the neck to involve the carotid space. CT is complementary to MRI in assessing jugular foramen lesions or for evaluating for carotid space lesions. Thin-cut high-resolution bone algorithm windows are useful to delineate skull base fractures, hyperostosis, skull base erosion, intratumoral calcification, and the bony margins of the jugular foramen and nearby skull base foramina [144-148]. Contrast should be administered. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CTA Head and Neck Most brainstem syndromes are due to brainstem infarctions and hemorrhages, which are best imaged with MRI [132]. CTA may be complementary to CT or MRI to characterize the vasculature in these clinical scenarios. Cranial Neuropathy When dissection of the internal carotid artery is clinically suspected as a cause of multiple lower CN palsies, CTA may be useful to evaluate for dissection, particularly in the emergent setting. In a study comparing CTA with conventional angiography, CTA had a sensitivity of 66% when evaluating for blunt carotid vascular injury, with most false-negatives representing low grade injuries [190]. In a comparative study, multidetector CT/CTA demonstrated more features of cervical artery (internal carotid and vertebral arteries) dissection compared with MRI/MRA. There was no significant reader preference for MRI/MRA compared with CT/CTA when evaluating for internal carotid artery dissection. MRI/MRA provided additional characterization of ischemic complications [191].