Opsoclonus-myoclonus syndrome associated with human herpes virus-6 rhomboencephalitis

Abstract Opsoclonus–myoclonus syndrome (OMS) is characterized by opsoclonus and arrhythmic-action myoclonus that predominantly involves the trunk, limbs, and head. Human herpes virus-6 (HHV-6) can rarely cause encephalitis in immunocompetent children and adults. Here we report on a case of OMS associated with HHV-6 rhomboencephalitis. HHV-6 infection should be considered in OMS adults and detection of cell-free viral DNA, indicative of active infection, is mandatory in such cases.