Acute demyelination mimicking vascular hemicrania.

A 29-year-old woman presented with acute hemicrania, trigeminal neuropathy and posterior fossa dysfunction. The admission differential diagnosis included vertebral artery dissection, posterior circulation aneurysm, vascular malformation and brainstem infarction. However, radiographic and CSF studies indicated demyelination. Acute demyelination should be in the differential diagnosis of vascular hemicrania with signs of posterior fossa dysfunction.