Abstract
Paraneoplastic neurologic syndrome (PNS) is an association of various cancer types and is reported to occur in small-cell lung cancers (SCLC). It is a nervous disturbance caused by immune-mediated mechanisms with various neurological symptoms. Immune checkpoint inhibitors (ICIs) are increasingly being used to treat SCLC. We report the case of a 69-year-old woman with SCLC complicated by PNS who experienced worsening neurological symptoms (Sensory disturbance, sensory ataxia, and autonomic symptoms) after receiving atezolizumab. The patient's neurological symptoms partially improved after the immunological treatment. Her neurological symptoms did not worsen and her lung cancer remained stable. We believe that ICIs will be increasingly used in the future for SCLC and that we will encounter more cases of PNS that may merge with SCLC deteriorating after receiving ICIs. We describe one case and review the clinical characteristics of patients with SCLC whose PNS was exacerbated by ICIs, including patients with SCLC whose PNS were present prior to the initiation of ICIs. We suggest that neurological symptoms suggestive of PNS should be carefully monitored after the introduction of ICIs for SCLC.