Chronic infectious inflammatory diseases of the central nervous system

Abstract

Chronic infections of the central nervous system (CNS) tend to progress over months or years. The incubation period is usually considerably longer than that of acute infections. Chronic infections of the CNS could be triggered by persistence of infecting organisms in the brain or spinal cord causing direct tissue damage (e.g. neurosyphilis, CNS tuberculosis) or by the host immunological response in the absence of continuing infection. Often both factors are involved. Onset of symptoms is usually subacute, and CSF fi ndings include predominantly lymphocytic pleocytosis and elevated protein and sometimes decreased glucose level. Several CNS-prone microorganisms are diffi cult to eradicate from CNS, and confi rmation of diagnosis may be challenging, but it is critical for prognosis. Infecting organisms are rarely detected in the CSF by classical culture methods. The methods used for diagnosis are either serological tests of blood or CSF (e.g. HIV, Lyme borreliosis, syphilis) or detection of nucleic acids in the CSF (Table 15.1). CNS infl ammation is confi rmed by the CSF examination that may need repeated examinations. In infections associated with the persistence of microorganisms, longterm antibacterial therapy is recommended (syphilis, TBE, toxoplasmosis, Lyme borreliosis). In diseases in which host immunological response plays a predominant role, the treatment of chronic CNS infection is usually symptomatic.