Intractable seizure disorder associated with chronic herpes infection - HSV1 detection in tissue by the polymerase chain reaction

We describe the pathological findings and report the detection of herpes simplex virus 1 (HSV1) in the brain in three patients who presented with intractable seizures. All three patients had a previous history of HSV1 encephalitis and went on to develop a medically refractory seizure disorder necessitating surgical intervention. HSV1 encephalitis was clinically diagnosed and treated at 6 months, 3 years, and 7 months and surgical resection was done at 8.5 years, 6 years, and 3 years, in cases 1, 2 and 3, respectively. Pathological examination revealed chronic encephalitis in all three cases, with microglial nodules, intraparenchymal, perivascular and meningeal lymphocytic infiltrates, and gliosis. While immunohistochemical and ultrastructural studies were negative for viral pathogens, polymerase chain reaction (PCR) analysis revealed HSV1 genome. These cases represent examples of chronic herpes encephalitis and seizure disorder with presence of viral genome in the brain long after the initial episode of treated herpes encephalitis.