Optic Chiasm Involvement Secondary to Herpetic Encephalitis. A Case Report

Herpes simplex (HSV) encephalitis is one of the most common central nervous system (CNS) viral infections in adults. Early diagnosis is essential for treatment. We describe the case of a 70-year-old man who reported sudden bilateral reduction of visus. Four days after admission the patient showed high fever, followed the next day by a generalised convulsive crisis and coma. A first magnetic resonance imaging (MRI) showed no alterations, whereas the second showed the usual patterns of HSV encephalitis. With a clinical suspicion of herpetic encephalitis an intravenous therapy with acyclovir was established. The diagnosis of herpetic encephalitis was confirmed by cerebrospinal fluid (CSF) detection of herpes simplex DNA sequences. A further ten days later we performed a third MRI, demonstrating the typical pattern of HSV encephalitis and an increase in size and signal of the optic chiasm.