St Vitus's dance an old-fashioned term for Sydenham's chorea, a neurological disorder in children characterized by jerky involuntary movements; it is so named because appealing to St Vitus was believed to alleviate the disease.
Saint Vitus (vī´təs), 4th cent.?, Sicilian martyr. Vitus is invoked against diseases including epilipsy, nervous disorders, and St. Vitus' Dance (Sydenham's chorea). He is one of the Fourteen Holy Helpers, a collective cult of saints that originated in the 14th-century Rhineland, believed to intercede effectively against various diseases. Vitus is traditionally the patron of dancers and actors. His nurse and her husband, St. Crescentia and St. Modestus, martyred with St. Vitus, share his feast, June 15.