- Patients with saved diagnosis of CRPS of the upper extremity based on the current used criteria for diagnosis plus a positiv 3-phase-sceletal-scintilgraphy, if they show pathological PPT-values in QST on the ipsilateral site (Z-values > 2 in age- and gender-based Z-transformation of the raw values)• age ≥ 18 years• Existence of an age-based normal creatinin-clearance (calculated with a defined formula)