Herpes Simplex Encephalitis Affecting the Entire Limbic System

Abstract

A 70-year-old woman with a history of multiple myeloma presented with somnolence, fever, and generalized muscle stiffness. Initial magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) parameters, and herpes simplex virus type 1 polymerase chain reaction results were unremarkable. Treatment included acyclovir, but her condition deteriorated. A follow-up MRI scan revealed extensive bilateral fluid-attenuated inversion recovery (FLAIR) hyperintensities with right-sided preponderance not only in the basal frontotemporal cortex and hippocampus but also the cingulum and insula. Thus, the MRI findings indicated specific involvement of the limbic system, consistent with limbic encephalitis. Although herpes simplex encephalitis may rarely include brain areas other than the basal temporal lobe,1Tyler K.L. Update on herpes simplex encephalitis.Rev Neurol Dis. 2004; 1: 169-178PubMed Google Scholar paraneoplastic limbic encephalitis was considered a likely differential diagnosis.2Tüzün E. Dalmau J. Limbic encephalitis and variants: classification, diagnosis and treatment.Neurologist. 2007; 13: 261-271Crossref PubMed Scopus (319) Google Scholar The diagnosis of autoimmune limbic encephalitis requires positive CSF results for autoantibodies such as anti-Hu, anti-Ri, anti-Yo or anti-VGCC. Treatment mainly consists of corticosteroid therapy.2Tüzün E. Dalmau J. Limbic encephalitis and variants: classification, diagnosis and treatment.Neurologist. 2007; 13: 261-271Crossref PubMed Scopus (319) Google Scholar In our patient, repeated CSF analysis yielded negative titers for autoantibodies. However, based on lymphocytosis, elevated protein, and positive herpes simplex virus type 1 polymerase chain reaction results, the diagnosis of limbic herpes simplex encephalitis was established. Despite antiviral treatment, the patient died. Immunocompromised patients with herpes simplex encephalitis may initially present with unremarkable CSF and radiological findings but nonetheless develop extensive and eventually fatal disease. FIGURE 2Brain MRI: Bilateral fluid-attenuated inversion recovery (FLAIR) hyperintensities in hippocampus and insula.View Large Image Figure ViewerDownload (PPT)