In patients with clinical features of trigeminal neuropathy, initial imaging is performed along the entire course of the trigeminal nerve to evaluate for a causative lesion [57]. The trigeminal nerve can be affected by processes anywhere along its course from the brainstem to its peripheral branches; consequently, imaging should cover the entire course of the nerve. Brainstem lesions can affect the trigeminal nerve but rarely lead to isolated trigeminal neuropathy because of the close proximity of neural structures within the brainstem. In particular, multiple sclerosis can result in trigeminal neuralgia, necessitating imaging of the brainstem to look for demyelinating disease [58-61]. Other brainstem lesions that can affect the trigeminal nerve include infarction, hemorrhage, vascular lesions (such as compressing vascular loops, aneurysms, and Cranial Neuropathy vertebrobasilar dolichoectasia), inflammatory and infectious conditions (such as meningitis, encephalitis, sarcoidosis, and demyelinating disease), and tumors (such as gliomas, lymphomas, and metastases) [59]. Tumors, vascular lesions, and inflammatory processes may also affect the cisternal, dural cave, cavernous, foraminal, and extracranial branches of the nerve as they traverse the Meckel cave, the pterygopalatine fossa, the orbit, the skull base, and the masticator space [59,62,63]. Perineural spread of tumor, discussed in Variant 10, can affect the trigeminal nerve anywhere along its course. CT Head CT is a complementary study for evaluating the osseous integrity of the skull base and neural foramina. However, standard coverage with a CT Head is insufficient to evaluate the full extent of the trigeminal nerve divisions in the face. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CT Maxillofacial Maxillofacial CT is a complementary study for evaluating the osseous integrity of the skull base and neural foramina, which can be accomplished without IV contrast.
Cranial Neuropathy. In patients with clinical features of trigeminal neuropathy, initial imaging is performed along the entire course of the trigeminal nerve to evaluate for a causative lesion [57]. The trigeminal nerve can be affected by processes anywhere along its course from the brainstem to its peripheral branches; consequently, imaging should cover the entire course of the nerve. Brainstem lesions can affect the trigeminal nerve but rarely lead to isolated trigeminal neuropathy because of the close proximity of neural structures within the brainstem. In particular, multiple sclerosis can result in trigeminal neuralgia, necessitating imaging of the brainstem to look for demyelinating disease [58-61]. Other brainstem lesions that can affect the trigeminal nerve include infarction, hemorrhage, vascular lesions (such as compressing vascular loops, aneurysms, and Cranial Neuropathy vertebrobasilar dolichoectasia), inflammatory and infectious conditions (such as meningitis, encephalitis, sarcoidosis, and demyelinating disease), and tumors (such as gliomas, lymphomas, and metastases) [59]. Tumors, vascular lesions, and inflammatory processes may also affect the cisternal, dural cave, cavernous, foraminal, and extracranial branches of the nerve as they traverse the Meckel cave, the pterygopalatine fossa, the orbit, the skull base, and the masticator space [59,62,63]. Perineural spread of tumor, discussed in Variant 10, can affect the trigeminal nerve anywhere along its course. CT Head CT is a complementary study for evaluating the osseous integrity of the skull base and neural foramina. However, standard coverage with a CT Head is insufficient to evaluate the full extent of the trigeminal nerve divisions in the face. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CT Maxillofacial Maxillofacial CT is a complementary study for evaluating the osseous integrity of the skull base and neural foramina, which can be accomplished without IV contrast.