Calcineurin Inhibitor Encephalopathy

Calcineurin inhibitor encephalopathy (CIE) is a rare condition occurring in patients who are undergoing treatment with drugs from the calcineurin inhibitor (CI) family of immunosuppressants, either cyclosporine (CsA) or tacrolimus (TAC, FK506). Generally acute in onset, the symptoms are commonly reversible if properly managed in a timely fashion. The differential diagnosis is broad and an evaluation should include toxic, metabolic, infectious and ischemic causes, with abnormal cerebrospinal fluid (CSF) results (aside from elevated protein concentration in isolation), suggesting an etiology other than CIE. Neurologic deficits are generally reversible; however, the risk of permanent deficits or poor outcomes increases the longer the condition goes unrecognized.