Posterior Reversible Encephalopathy Syndrome following Ustekinumab Induction for Crohn's Disease.

Biological agents are frequently used in the management of inflammatory bowel disease, and it is important to understand the potential adverse effects of these therapies. Ustekinumab is a human monoclonal antibody that interferes with interleukin-12 and -23 cytokine signaling and is approved for the treatment of moderate to severe Crohn's disease. We report 2 cases of neurological adverse events, one of which is consistent with posterior reversible encephalopathy syndrome (PRES), in the setting of ustekinumab therapy for Crohn's disease. The first patient had a seizure and classic neuroimaging features of PRES following induction with ustekinumab. The second patient presented with acute encephalopathy and atypical imaging findings concerning for PRES after ustekinumab induction. Both patients recovered fully following cessation of ustekinumab therapy. PRES associated with ustekinumab is uncommon, but must be a consideration in Crohn's disease patients receiving this therapy who present with focal neurological symptoms or change in mentation.