Subcutaneous Stimulation as Add on Therapy to SCS toTreat Low Back Pain in FBSS

Aim of the study Failed back surgery syndrome (FBSS) is a clinical entity consisting of chronic leg and /or back pain due to radicular nerve damage. The effectiveness of Spinal Cord Stimulation (SCS) in the pain management of patients with FBSS is proven. Patients mostly have dominant leg pain, however a significant percentage of FBSS patients has a more pronounced back pain and are commonly excluded from SCS as it is often inadequate in relieving both the back and leg pain components. Recently some reports showed the benefit of subcutaneous stimulation (SubQ) for low back pain in patients with FBSS. This has been confirmed by a feasibility study performed by our group. The aim of the randomized controlled study is to evaluate the effect of SubQ on low back pain in FBSS patients for whom SCS gives an inadequate back pain relief. Hypothesis We hypothesize that SubQ in addition to SCS in FBSS patients with leg and low back pain is more effective in treating low back pain (i.e. \>50% pain reduction) than SCS alone.