Adult-onset opsoclonus-myoclonus syndrome due to West Nile Virus treated with intravenous immunoglobulin

A 63-year-old female with no significant past medical historywas presented with a 5-day history of progressive opsoclonus- myoclonus, headaches, and fevers. Her workup was significant only for positive West-Nile Virusserum serologies. She received a 2-day course of intravenous immunoglobulin(IvIG). At an 8-week follow up, she had a complete neurological remission. Adult-onset opsoclonus-myoclonus syndromeis a rare condition for which paraneoplastic and infectious causes have been attributed. To our knowledge, this is the first case reported of opsoclonus- myoclonussecondary to West-Nile Virustreated with intravenous immunoglobulinmonotherapy.