Langford, et al. 2013 Double-blind, parallel RCT Grade 2- moderate Langford RM, Mares J, Novotna A, Vachova M, Novakova I, Notcutt W, et al. A double-blind, randomized, placebo-controlled, parallel-group study of THC/CBD oromucosal spray in combination with the existing treatment regimen, in the relief of central neuropathic pain in patients with multiple sclerosis. Journal of Neurology 2013; 260: 984-97. 339 patients at 33 sites in UK, Czech Republic, Canada, Spain and France with a mean age of 49 and central neuropathic pain due to MS were randomised to treatment with nabiximols (Sativex) spray (maximum dose 12 sprays per day or placebo) in combination with existing treatment over 14 weeks.