Chronic herpes simplex type-1 encephalitis with intractable epilepsy in an immunosuppressed patient

Background Chronic herpes simplex virus type-1 encephalitis (HSE-1) is uncommon. Past reports focused on its association with prior documented acute infection. Here, we describe a patient with increasingly intractable epilepsy from chronic HSE-1 reactivation without history of acute central nervous system infection. Case presentation A 49-year-old liver transplant patient with 4-year history of epilepsy after initiation of cyclosporine developed increasingly frequent seizures over 3 months. Serial brain magnetic resonance imaging showed left temporoparietal cortical edema that gradually improved despite clinical decline. Herpes simplex virus type-1 (HSV-1) DNA was detected in cerebrospinal fluid by polymerase chain reaction. Cerebrospinal fluid HSV-1&2 IgM was negative. Seizures were controlled after acyclovir treatment, and the patient remained seizure free at 1-year follow-up. Conclusion Chronic HSE is a cause of intractable epilepsy, can occur without a recognized preceding acute phase, and the clinical course of infection may not directly correlate with neuroimaging changes.