Herpes simplex encephalitis initially presented with parietal cortex lesions mimicking acute ischemic stroke: A case report

Abstract

A 73-year-old woman was admitted to our hospital due to a decreased conscious level and a high fever. Six days before her admission, she felt transient numbness in her right lower limb. Brain MRI taken by her local doctor revealed only right parietal cortex lesions. She was diagnosed with transient ischemic attack and started on anti-platelet therapy. One day before her admission, she became drowsy, and left-side weakness developed. She was admitted to a community hospital for treating stroke. On the next day, she was referred to our hospital because of a high fever. Our brain MRI showed new lesions in her right temporal lobe. She had no stroke risk factors, and embolic sources were not detected. Cerebrospinal fluid analysis detected herpes simplex virus DNA. She was diagnosed with herpes simplex encephalitis (HSE). HSE is common encephalitis which develops fever, headache and alteration in mental status. It often involves temporal lobe, but extratemporal lesions alone are not uncommon. Diffusion-weighted images (DWI) of brain are of importance to differentiate HSE from stroke. When it is questionable to diagnose with stroke for patients with cerebral cortex lesions, they must be monitored with close observation. There is the possibility of initial presentation of HSE in that situation even if patients have no typical symptoms.