Nivolumab-Associated Acute Demyelinating Encephalitis: A Case Report and Literature Review.

Nivolumab is a checkpoint inhibiting immunotherapeutic agent prescribed for the treatment of resistant cancers. Many immune-related adverse effects including neurological effects have been described, but central nervous system (CNS) toxicities are rarely reported. We present a 59-year-old Caucasian woman with a history of treatment-resistant, progressive, laryngeal squamous cell carcinoma. She received nivolumab and presented with gradual weakness, confusion, and progressive dyspnea. Magnetic resonance imaging of the head showed multifocal cerebral demyelination, primarily involving the parietal lobe. The diagnosis of acute demyelinating encephalitis was made. She improved dramatically after stopping nivolumab and receiving treatment with high-dose intravenous steroid and immunoglobin therapy. We conclude, from this case and literature review, that immune checkpoint inhibitor treatment requires more investigation to determine if autoimmune encephalitis with demyelination can occur as a severe form of immune-related adverse events. CNS toxicity appears to be reversible with prompt cessation of immunotherapy followed by treatment with high doses of steroid with or without intravenous immunoglobulin therapy.