Despite available treatment with intravenous immunoglobulin (IVIg), morbidity and mortality are considerable in patients with Guillain-Barré syndrome (GBS). Our aim was to assess whether methylprednisolone, when taken with IVIg, improves outcome when compared with IVIg alone.

We did a double-blind, placebo-controlled, multicentre, randomised study, to which we enrolled patients who were unable to walk independently and who had been treated within 14 days after onset of weakness with IVIg (0·4 g/kg bodyweight per day) for 5 days. We assigned 233 individuals to receive either intravenous methylprednisolone (500 mg per day; n=116) or placebo (n=117) for 5 days within 48 h of administration of first dose of IVIg. Because age is an important prognostic factor, we split treatment groups into two age-groups—ie, younger than age 50 years, or 50 years and older. Our primary outcome was an improvement from baseline in GBS disability score of one or more grades 4 weeks after randomisation. Analysis was by intention to treat.

We analysed 225 patients. GBS disability scores increased by one grade or more in 68% (76 of 112) of patients in the methylprednisolone group and in 56% (63 of 113) of controls (odds ratio [OR] 1·68, 95% CI 0·97–2·88; p=0·06). After adjustment for age and degree of disability at entry, treatment OR was 1·89 (95% CI 1·07–3·35; p=0·03). Side-effects did not differ greatly between groups.

We noted no significant difference between treatment with methylprednisolone and IVIg and IVIg alone. Because of the relevance of prognostic factors and the limited side-effects of methylprednisolone, the potential importance of combination treatment with the drug and IVIg, however, warrants further investigation.