Abstract
We report a case of probable encephalitis presenting as narcolepsy with cataplexy, but with cyclical exacerbation and cognitive difficulties. Our patient continued to worsen despite treatment for narcolepsy and later was thought to have an immune-mediated encephalopathy. Treatment with intravenous gamma immunoglobulin (IVIG) led to complete recovery. Cyclic symptoms of narcolepsy with cataplexy are thus one presentation of probable immune-mediated encephalitis.