43 - Central nervous system viral infections: Clinical aspects and pathogenic mechanisms

Abstract

This chapter reviews the general aspects of human central nervous system (CNS) viral infections, together with basic pathogenic mechanisms and diagnostic tools. The focus is on two prototypical CNS viral infections, herpes simplex virus encephalitis and human immunodeficiency virus dementia, which highlight many of the concepts that underlie the clinical presentation, diagnosis, and treatment of these diverse groups of neurological disorders. Unlike systemic infections, infectious pathogens in the CNS pose a more ominous predicament for clinicians because of the brain's enhanced vulnerability due to its limited host defenses, which are largely dependent on innate immunity in many diseases, including HIV and rabies virus infections. The use of molecular tools for infectious disease epidemiology is the cornerstone of controlling disease outbreaks and monitoring ongoing epidemics. Indeed, a greater understanding of host susceptibility to infection has arisen through the identification of specific genotypes associated with disease including single nucleotide polymorphisms. Neurological diagnostics and therapeutics have also evolved with the advent of improved neuroimaging, highly sensitive and specific molecular tools, elaborate neurocognitive testing, and the wider availability of specific drugs for neurological infections. Similarly, immunotherapies including intravenous immunoglobulin, plasmapheresis, and immunosuppressive drugs have substantial impact neurological disease morbidity and mortality.