diagnostic criteria were developed in the late 1970s after the series of cases associated with swine flu vaccination. these were refined in 1990. the case definition was revised by the brighton collaboration for vaccine safety in 2009, but is mainly intended for research. plasma exchange was first used in 1978 and its benefit confirmed in larger studies in 1985. intravenous immunoglobulins were introduced in 1988, and its non-inferiority compared to plasma exchange was demonstrated in studies in the early 1990s.