Herpes Simplex Virus Encephalitis: Laboratory Evaluations and Their Diagnostic Significance

Abstract

Laboratory procedures were compared with brain biopsy findings in 113 biopsy-proven patients with herpes simplex virus (HSV) encephalitis and 93 biopsy-negative individuals. Examinations of brain tissue by histopathology, immunofluorescence, and electron microscopy demonstrated evidence of HSV infection in 56%, 70%, and 45% of proven cases and apparently false-positive results in 14%,9%, and 2% of those biopsynegative. Serologic assessments revealed that HSV encephalitis occurred as both a primary (30%) and recurrent (70%) infection. Among patients with HSV encephalitis, 28% failed to seroconvert or seroboost within one month of the onset of disease. Titers of passive hemagglutinating and IgG immunofluorescent antibodies increased fourfold in the cerebrospinal fluid in 74% and 94%, respectively, of patients with proven disease. Similar percentages of patients had antibody ratios in serum and cerebrospinal fluid of ≤20 over the same interval. These data indicate the need for development of noninvasive diagnostic procedures.