Distinctive Disease Entity of Neurological Adverse Events Associated with Immune Checkpoint Inhibitors

Neurological immune-related adverse events (irAEs) associated with cancer treatment with immune checkpoint inhibitors (ICIs) are infrequent but are sometimes serious and require prompt diagnosis and management. Among diverse clinical subsets, meningoencephalitis, polyradiculoneuropathy, myasthenia gravis, and myositis are particularly important. The clinical presentation may be different from that of patients with those conditions unrelated to ICIs. A broad range of clinical symptoms complicates the diagnosis of autoimmune encephalitis. The clinical features of aseptic meningitis induced by classical drugs and ICIs are different. Polyradiculoneuropathy, usually diagnosed as Guillain-Barre syndrome or chronic inflammatory demyelinating polyneuropathy, requires prompt diagnosis. However, the clinical manifestations and laboratory findings of patients with polyradiculoneuropathy may be unique and differ from those in the preexisting disease subset. Although myasthenia gravis and myositis are usually independent diseases, it is often difficult to diagnose myasthenia gravis or myositis independently when the disease is associated with irAEs. We believe that inflammatory myopathy associated with ICIs is a novel disease entity accompanied by possible biomarkers of anti-striational antibodies. Discontinuation of immune checkpoint inhibitors and steroid treatment is recommended with a good response. A correct understanding of neurological adverse events is required for the best management of cancer patients.