Iatrogenic CNS demyelination in the era of modern biologics

The number of reported cases of iatrogenic demyelination of the central nervous system (CNS) is on the rise. This is, in part, related to the recent expansion in the use of biologics. Review of literature from the past decade suggests that in addition to vaccines, tumor necrosis factor (TNF)-alpha inhibitors and checkpoint inhibitors are the most frequently cited inducers of central inflammation. About one-third of demyelinating cases in the setting of TNF-alpha inhibitors evolve into full-blown multiple sclerosis. In addition to demyelination, checkpoint inhibitors may also cause accelerated paraneoplastic encephalitis and other antibody-mediated conditions. Luckily, the overall prognosis of iatrogenic central inflammation is favorable, with most cases having partial or complete response to steroids and discontinuation of the offending agent. Long-term monitoring and initiation of maintenance immune-modulating therapy may be necessary in some patients. In this article, we provide an updated review of biologic-induced inflammation of the CNS.