Three cases of isolated one-and-a-half syndrome with facial nerve palsy related to infarction are presented. Magnetic resonance imaging in cases 1 and 2 was unremarkable, whereas magnetic resonance angiography demonstrated pathophysiologically significant vertebral basilar disease. Case 3 is unique due to its association with giant cell arteritis. Ipsilateral adduction improved to a greater extent than abduction in each case, perhaps providing insight into the exact localization of these lesions or selective vulnerability of the ocular motor structures within the pons. This combination of clinical findings, termed the 8-1/2 syndrome (cranial nerve 7 + 1-1/2), allows precise localization, and magnetic resonance angiography appears to be the imaging study of choice.
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