Sativex Versus Placebo When Added to Existing Treatment for Central Neuropathic Pain in MS

The purpose of this study is to find out if cannabis-based medicine compared to a dummy medicine (placebo that contains no active ingredient) can help the central neuropathic pain patients experience as a result of multiple sclerosis. This type of pain "central neuropathic pain" is described as shooting, stabbing, burning or searing like sensation, which is often worse at night.