Therefore, in this investigator blinded, cross-over study, 6 patients suffering from upper limb spasticity, including musculus biceps brachii, will be investigated. (Magnetic Resonance Tomography) MRI of the musculus biceps brachii will be performed at two consecutive, routine BoNT-injection days (baseline and week 16). Patients receive dosage as clinically indicated, due to routine treatment. Patients will be randomised to receive thirty minutes of physiotherapy of the affected arm, including exercise of the elbow flexors, at one of the injection days (baseline, or week 16, respectively). In addition, MRI will be repeated 3 weeks after injection.