Ischemic and hemorrhagic infarcts are the most frequent cause of acute brainstem syndromes, which can result in multiple middle CN palsies [131,132,135]. CTA may be complementary to brain MRI or head CT to characterize the vasculature in these clinical scenarios. Cranial Neuropathy FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use FDG-PET/CT skull base to mid-thigh in the initial evaluation of multiple middle cranial palsies. MRA Head There is no relevant literature to support routine use of MRA head in the initial evaluation of multiple middle cranial palsies. Ischemic and hemorrhagic infarcts are the most frequent cause of acute brainstem syndromes, which can result in multiple middle CN palsies [131,132,135]. MRA may be complementary to MRI brain to characterize the vasculature in these clinical scenarios. DWI can be used to assess for acute brainstem infarction, cholesteatoma, and for characterizing tumor cellularity. False-negative DWI can occur in the setting of very small ischemic brainstem infarcts [137,138]. Thin-section coronal DWI or thinner axial DWI may improve sensitivity for detecting acute brainstem infarction, with nearly 25% of acute brainstem infarcts more easily seen on thin-cut coronal DWI compared with standard axial DWI in one study [138]. The combination of ipsilateral CN V and CN VII palsies raises concern for perineural spread of a tumor, which is discussed in Variant 10. DWI can be used to assess for acute brainstem infarction, cholesteatoma, and for characterizing tumor cellularity. False-negative DWI can occur in the setting of very small ischemic brainstem infarcts [137,138]. Thin-section coronal DWI or thinner axial DWI may improve sensitivity for detecting acute brainstem infarction, with nearly 25% of acute brainstem infarcts more easily seen on thin-cut coronal DWI compared with standard axial DWI in one study [138].
Cranial Neuropathy. Ischemic and hemorrhagic infarcts are the most frequent cause of acute brainstem syndromes, which can result in multiple middle CN palsies [131,132,135]. CTA may be complementary to brain MRI or head CT to characterize the vasculature in these clinical scenarios. Cranial Neuropathy FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use FDG-PET/CT skull base to mid-thigh in the initial evaluation of multiple middle cranial palsies. MRA Head There is no relevant literature to support routine use of MRA head in the initial evaluation of multiple middle cranial palsies. Ischemic and hemorrhagic infarcts are the most frequent cause of acute brainstem syndromes, which can result in multiple middle CN palsies [131,132,135]. MRA may be complementary to MRI brain to characterize the vasculature in these clinical scenarios. DWI can be used to assess for acute brainstem infarction, cholesteatoma, and for characterizing tumor cellularity. False-negative DWI can occur in the setting of very small ischemic brainstem infarcts [137,138]. Thin-section coronal DWI or thinner axial DWI may improve sensitivity for detecting acute brainstem infarction, with nearly 25% of acute brainstem infarcts more easily seen on thin-cut coronal DWI compared with standard axial DWI in one study [138]. The combination of ipsilateral CN V and CN VII palsies raises concern for perineural spread of a tumor, which is discussed in Variant 10. DWI can be used to assess for acute brainstem infarction, cholesteatoma, and for characterizing tumor cellularity. False-negative DWI can occur in the setting of very small ischemic brainstem infarcts [137,138]. Thin-section coronal DWI or thinner axial DWI may improve sensitivity for detecting acute brainstem infarction, with nearly 25% of acute brainstem infarcts more easily seen on thin-cut coronal DWI compared with standard axial DWI in one study [138].