Diagnosis of herpesvirus infections of the central nervous system

The International Herpes Management Forum (IHMF) has produced guidelines to promote improved diagnosis of herpesvirus infections of the central nervous system (CNS). Recommendations include using polymerase chain reaction (PCR) analysis of cerebrospinal fluid (CSF) to help diagnose herpes simplex virus (HSV), varicella zoster virus (VZV) and cytomegalovirus (CMV) infections of the CNS. Laboratories routinely using such tests should participate in a proficiency testing programme. For retrospective diagnosis of herpesvirus infections of the CNS, intrathecal antibody detection can be used as an adjunct to PCR, assuming all appropriate controls are utilized. For suspected cases of herpes simplex encephalitis (HSE), a sensitive HSV PCR test of the CSF should be used in preference to other methods. Cultures are not recommended for HSE except as an adjunctive test in suspected neonatal HSV infections. While research continues into the role of PCR with VZV infections of the CNS, studies demonstrate that the technique is useful for diagnosing varicella-associated CNS syndromes but further research is required for its role in zoster-associated syndromes. For CMV CNS infections, PCR represents the most sensitive diagnostic method and can be used in conjunction with virus culture to determine suspected cases of CMV myelitis. For CNS infections with lymphotropic herpesviruses, a positive PCR test is suggestive, but not definitive, evidence of virus encephalitis. PCR analysis of CSF for Epstein-Barr virus can be useful for diagnosing AIDS-associated primary CNS lymphoma. This article presents the current evidence for these and other guidelines for the diagnosis of herpesvirus infections of the CNS.