 Baseline assessment will be followed by randomisation and dose introduction. Patients will be randomly assigned to two counterbalanced groups starting either with Sativex or with placebo as the first drug. They will be dispensed sufficient study medication for two weeks together with a diary. During the two-week treatment period all the patients will have to be reached the optimal, individualised dosage to subjectively relief spasticity.Patient will return after three weeks and they will undergo the fMRI and neurophysiological evaluations.Then patients will perform a two-week washout period and they will be requested to intake the alternative medicine. After two weeks patients will perform a second fMRIneurophysiological study. Two weeks later, after a second washout period, a last visit will be performed to conclude the study. 