Drug Insight: steroids in CNS infectious diseases--new indications for an old therapy.

Infectious diseases of the CNS lead to overwhelming inflammatory processes within the brain and spinal cord that contribute substantially to patient morbidity and mortality. Pharmacological strategies to modulate inflammation have been investigated, although the resulting guidelines have sometimes been contradictory. Steroids have been proposed as adjunctive treatments for bacterial meningitis, tuberculous meningitis and herpes simplex virus encephalitis. Well-designed randomized controlled trials have established dexamethasone as an adjunctive therapy for adult patients receiving antibiotics for bacterial meningitis, and physicians prescribing the initial antibiotics need to be aware of current guidelines. Morbidity and mortality in patients with tuberculous meningitis exceeds 50%. Steroid treatments reduce mortality through an as yet unknown mechanism, although their effects on morbidity are less clear. Herpes simplex virus encephalitis is also associated with considerable morbidity and mortality. Despite a lack of randomized trials, there is some evidence that steroids used alongside antiviral therapy might be beneficial in this condition. As we discuss in this Review, systemic steroid treatment is an important aspect of treatment regimens for CNS infectious diseases, and the recent literature provides guidelines for the use of steroids in combination with appropriate antimicrobial therapy.