Immune reconstitution inflammatory syndrome and the central nervous system

Purpose of review Central nervous system-immune reconstitution inflammatory syndrome (CNS-IRIS) is a recently recognized, devastating, T-cell-mediated encephalitis that occurs in the setting of treatment of HIV infection or autoimmune diseases, the management of which remains challenging. We review the pathophysiology, the clinical subtypes and present guidelines for prevention, diagnosis and treatment of this entity. Recent findings Nearly all patients with multiple sclerosis who develop progressive multifocal leukoencephalopathy (PML) following treatment with natalizumab develop IRIS which carries a high morbidity and mortality rate. Chronic lymphocyte activation is commonly present in the CNS of HIV-infected patients despite adequate treatment with antiretroviral therapy (ART), suggesting that a chronic from of CNS-IRIS may contribute to the neurocognitive impairment in this population. Summary The risk for CNS-IRIS can be decreased by starting ART early in the course of the illness or by reducing antigenic burden with antimicrobial treatment for opportunistic infections prior to starting ART. Of all the forms of CNS-IRIS, the management of IRIS associated with PML due to JC virus infection remains the most challenging, as no antimicrobial drug against this virus is available and the treatment of IRIS requires the use of corticosteroids, which impair the immune cells needed to control the infection.