Lesions affecting the medulla oblongata, the subarachnoid space, or the posterior skull base, including the jugular foramen and hypoglossal canal, can lead to multiple CN palsies affecting CN IX through CN XII in variable patterns. Patients with medullary lesions will typically have additional neurologic findings such as long tract signs, nystagmus, vertigo, ataxia, nausea, and vomiting. A thorough neurologic examination evaluating for these associated signs can localize a process to the brainstem [18,135]. Imaging protocols can then be tailored to evaluate the suspected region of anatomy affected. Most brainstem syndromes are due to brainstem infarctions and hemorrhages [132]. Wallenberg syndrome or lateral medullary syndrome is typically due to occlusion of the posterior inferior cerebellar artery. Additional disorders that may affect the brainstem include demyelinating disease, primary brainstem tumors, metastasis, encephalitis, Arnold-Chiari malformations, and syringobulbia [18,132]. Multiple different jugular foramen syndromes are described based on variable patterns of CN palsies affecting CN IX through CN XII and include Vernet syndrome (IX, X, XI), Collet-Sicard syndrome (IX, X, XI, XII), and Villaret syndrome (IX, X, XI, XII and cervical sympathetic trunk). Lesions affecting the jugular foramen leading to jugular foramen syndromes include jugular foramen tumors (paragangliomas, schwannomas, and meningiomas), infection, leptomeningeal processes, metastasis, trauma, cholesteatoma, and vascular lesions [147,148,193]. Dissection of the internal carotid artery can result in isolated acute CN XII palsy or less commonly multiple variable patterns of CN palsies including involvement of CN IX through CN XII [185-187]. Leptomeningeal processes can lead to variable patterns of cranial neuropathy [18,132]. CT Head There is no relevant literature to support the use of routine head CT in the initial evaluation of multiple lower CN palsies.
Cranial Neuropathy. Lesions affecting the medulla oblongata, the subarachnoid space, or the posterior skull base, including the jugular foramen and hypoglossal canal, can lead to multiple CN palsies affecting CN IX through CN XII in variable patterns. Patients with medullary lesions will typically have additional neurologic findings such as long tract signs, nystagmus, vertigo, ataxia, nausea, and vomiting. A thorough neurologic examination evaluating for these associated signs can localize a process to the brainstem [18,135]. Imaging protocols can then be tailored to evaluate the suspected region of anatomy affected. Most brainstem syndromes are due to brainstem infarctions and hemorrhages [132]. Wallenberg syndrome or lateral medullary syndrome is typically due to occlusion of the posterior inferior cerebellar artery. Additional disorders that may affect the brainstem include demyelinating disease, primary brainstem tumors, metastasis, encephalitis, Arnold-Chiari malformations, and syringobulbia [18,132]. Multiple different jugular foramen syndromes are described based on variable patterns of CN palsies affecting CN IX through CN XII and include Vernet syndrome (IX, X, XI), Collet-Sicard syndrome (IX, X, XI, XII), and Villaret syndrome (IX, X, XI, XII and cervical sympathetic trunk). Lesions affecting the jugular foramen leading to jugular foramen syndromes include jugular foramen tumors (paragangliomas, schwannomas, and meningiomas), infection, leptomeningeal processes, metastasis, trauma, cholesteatoma, and vascular lesions [147,148,193]. Dissection of the internal carotid artery can result in isolated acute CN XII palsy or less commonly multiple variable patterns of CN palsies including involvement of CN IX through CN XII [185-187]. Leptomeningeal processes can lead to variable patterns of cranial neuropathy [18,132]. CT Head There is no relevant literature to support the use of routine head CT in the initial evaluation of multiple lower CN palsies.