Rapidly progressive dementia-associated N-type voltage-gated calcium channel antibody encephalopathy.

Autoimmune encephalopathy is one of the treatable causes of rapidly progressive dementia; however, it is often underdiagnosed. Autoantibodies against voltage-gated calcium channel (VGCC) have been linked to several neurological disorders, including Lambert-Eaton syndrome, but VGCC antibody-associated encephalopathy is uncommon. Herein, we present a case of a 74-year-old woman with prominent neuropsychiatric symptoms followed by rapid cognitive decline. Extensive initial studies were nondiagnostic. Subsequently, serum N-type VGCC antibody was positive. After treatment with intravenous immunoglobulin, the patient's cognition and neuropsychiatric symptoms significantly improved.