EDITOR, - Various authors criticised our report on Guillain-Barre syndrome after gangliosides.1 Francesco Grigoletto computed the cases of the syndrome expected by chance alone according to age specific frequencies of therapeutic cycles of gangliosides.2 Without defining “therapeutic cycle” he concluded that our 24 cases were equal to the number expected by chance in Italy. However, to obtain this result he considered one month after gangliosides were given as the period at risk, whereas we considered only the first three weeks and excluded cases with later …