[Herpes simplex encephalitis presenting as a stroke-like episode following a migraine attack: a case report]

A 23-year-old woman, who had been suffering from migraine since primary school age, presented with left arm paralysis three days after one such migraine attack. On admission, brain MRI diffusion-weighted imaging (DWI) demonstrated high-signal-intensity lesions in the white matter of the right fronto-parietal lobe, and no abnormal lesions were evident in the limbic system. Although the patient had a fever of 38.7°C, the CSF cell count was not elevated. On the 4‍^th day, the left arm paralysis worsened, with an increase in body temperature to 39.8°C. Brain MRI revealed that the white matter lesions had spread to the right postcentral gyrus and the bilateral insular cortex. Also, MR angiography demonstrated no spasms or dissection of the major vessels. On the 6‍^th day, the CSF cell count was elevated to 54/μl and herpes simplex virus DNA was detected. Acyclovir and steroid pulse therapy ameliorated the symptoms. Cervical artery dissection and reversible cerebral vasoconstriction are well known complications of migraine attack. However, herpes simplex encephalitis should also be considered as a differential diagnosis in patients with a high fever of unknown origin.