The objective of this study is to better determine the efficacy of MT. The investigators will therefore compare recovery of arm function in two groups of patient, that perform a regimen of 30 minutes of therapy, 5 times a week, for 4 weeks on top of conventional therapy. One group performs MT and the other one performs a therapy in which the same movements are performed, but without the use of a mirror, with unrestricted view of both limbs. Allocation to each group will be randomized. Arm function will be evaluated by use of a scale before, during and after the 4 week period. The assessor for the primary outcome measure will not know in which group the patient is. There will be a total of 30 patients included over a one year study period.