Viral Infections of the Central Nervous System

Abstract

Viral infections of the central nervous system (CNS) represent a significant burden to human health worldwide. Many viruses are able to cause neurologic disease such as herpes virus (HSV), varicella zoster virus (VZV), cytomegalovirus (CMV), Epstein–Barr virus (EBV), human enterovirus (HEV), rabies virus (RV) and arboviruses. Viral access to CNS is defined by two main routes, the haematogenous or peripheral nerve pathway. During a viral infection in the CNS, inflammation and damage can arise in distinct anatomical regions, such as the meninges, brain and spinal cord or even simultaneously in multiple regions (meningoencephalitis, encephalomyelitis). Diagnosis of these infections is crucial in order to establish adequate management and prevent sequelae. Key Concepts Viral infection of the central nervous system may present different viruses as causative agents. Central nervous system is protected by a highly complex barrier system represented by blood–brain and blood–cerebrospinal fluid barriers. Neurotropic viruses dribble blood–brain barriers through different ways. Once established in the central nervous system, viral infection results in inflammation and damage, which can affect distinct anatomical areas. Viral meningitis or aseptic meningitis includes inflammation restricted to the leptomeninges, the tissue which covers and protect the brain. Viral encephalitis refers to inflammation and damage comprising the brain parenchyma. Viral myelitis is defined by the inflammation that affects exclusively the spinal cord. Some viruses cause extended neurologic involvement which result in meningoencephalitis or encephalomyelitis. Diagnosis of infections of central nervous system is based on clinical picture, laboratorial findings and imaging techniques. Adequate management of viral infections of central nervous system are crucial in order to prevent sequelae.