Dysautonomia and dysosmia associated with anti-Hu antibodies induced by immune checkpoint inhibitors: a case report

Introduction The use of immune checkpoint inhibitors may cause neurological immune-related adverse events in patients. We, herein, report a case of autonomic nervous system involvement in nivolumab-induced autoimmune encephalitis with dysautonomia. Case presentation A 78-year-old man presented with a 4-month history of orthostatic hypotension, dysgeusia, and dysosmia following a 2-month course of nivolumab prescribed for malignant mesothelioma. Serum was positive for anti-neuronal nuclear antibody type 1. Diagnostic work-up that included imaging, neurological, and biochemical tests suggested the diagnosis of nivolumab-induced autoimmune encephalitis with pronounced autonomic nervous system involvement. On day 10 of hospitalisation, the patient received high-dose intravenous methylprednisolone followed by oral prednisone. The patient was discharged on day 29 with continued administration of corticosteroids and midodrine. At the 1-month outpatient follow-up, the patient remained stable and reported independent ambulation without marked orthostatic symptoms. Conclusions We discuss a possible mechanism of dysautonomia in this case and draw attention to newly emerging autonomic symptoms and olfactory impairments during therapy with immune checkpoint inhibitors.