43 years old woman with Crohn’s disease, been receiving adalimumab for 4 months prior to admission, admitted for acute onset encephalopathy and delirium including rapid behavior change, confusion, abnormal dystonic movements, catatonia, and visual hallucinations. Notably, there was no preceding infection, vaccination, fever, or headache. 

Extensive diagnostic workup, including brain imaging, cerebrospinal fluid analysis, autoantibody screening, and viral panels, all were unremarkable. Given high clinical suspicion of limbic encephalitis possibly due to adalimumab, she was started on five days of intravenous steroid followed by 5 sessions of plasma exchange therapy with excellent response. After 19 days of hospitalization, she was discharged home with a steroid tapering regimen. At four-weeks follow-up appointment, she reported a return to her baseline condition, with a score of 28/30 on the Montreal Cognitive Assessment test and no neurological deficits on examination.