Spinal cord stimulation for complex regional pain syndrome type I: a prospective cohort study with long-term follow-up.

OBJECTIVES: Spinal cord stimulation (SCS) is an effective treatment for intractable complex regional pain syndrome type I pain. Long-term data are scarce on effectiveness, degree of pain relief, predictors, and complications.

MATERIALS AND METHODS: From 1997 to 2008, 84 consecutive patients who received an implanted SCS system after positive test stimulation were included in the prospective study. Treatment effectiveness was assessed annually as measured by mean visual analog scale pain scores and with the Patients Global Impression of Change scale. Treatment success was defined as at least 30% mean pain relief at end point and treatment failure as explantation of the system. A Cox regression determined if baseline factors were associated with both these outcomes.

RESULTS: During 11 years, 41% (95% CI: 27-55) of the patients experience at least 30% pain relief at assessment end point. During 12 years of follow-up 63% (95%CI: 41-85) of the implanted patients still use their SCS device at measured end point. Pain relief of at least 50% one week following test stimulation is associated with a higher probability of long-term treatment success. In 51 patients, 122 reinterventions were performed over 12 years; 13 were due to complications, 44 to battery changes, and 65 reinterventions were equipment related.

CONCLUSION: SCS provides an effective long-term pain treatment for 63% (95%CI: 41-85) of implanted patients. Forty-one percent (95%CI: 27-55) of SCS treated patients have at least 30% pain reduction at measurement end point. The number of reinterventions after implantation due to equipment-related problems, battery changes, and complications is 122 over 12 years of follow-up. Sixty-one percent (N = 51) of the patients had at least one reintervention. Mean pain relief of at least 50% (visual analog scale) one week after the test stimulation is associated with long-term treatment success.