Amantadine for treatment of fatigue in Guillain-Barré syndrome: a randomised, double blind, placebo controlled, crossover trial - Garssen,M.P.; Schmitz,P.I.; Merkies,I.S.; Jacobs,B.C.; van der Meché,F.G.; van Doorn,P.A. (J Neurol Neurosurg Psychiatry, 2006)