The Long-Term Response to High-Dose Spinal Cord Stimulation in Patients With Failed Back Surgery Syndrome After Conversion From Standard Spinal Cord Stimulation: An Effectiveness and Prediction Study

Abstract

Objectives: Spinal cord stimulation (SCS) is nowadays available with several stimulation paradigms. New paradigms, such as high dose (HD-)SCS, have shown the possibility to salvage patients who lost their initial pain relief. The first aim of this study is to evaluate the effectiveness of HD-SCS after conversion from standard SCS. The second aim is to develop a model for prediction of long-term response of HD-SCS after unsatisfactory standard SCS. Materials and Methods: Seventy-eight patients with failed back surgery syndrome (FBSS) who are treated with standard SCS were enrolled in the study. Self-reporting questionnaires and outcomes were assessed before conversion and at 1, 3, and 12 months of HD-SCS. Longitudinal mixed models were used to determine the effectiveness of HD-SCS. Logistic regression and classification and decision tree analyses were performed to predict responders (NRS decrease ≥2/10) after 12 months of HD-SCS. Results: Significant time effects were found for both low back and leg pain responders, suggesting the effectiveness of HD-SCS after conversion. Logistic regression models revealed the importance of pain intensity scores, medication use, paresthesia coverage (for back pain) and EQ5D (for leg pain) as predictors for being a responder after 12 months of HD-SCS. Conclusions: Converting patients with unsatisfactory responses from standard SCS to HD-SCS may be an effective strategy to obtain and maintain pain relief in a challenging subgroup of patients with FBSS refractory to standard SCS. The prediction models may guide clinicians in their decision making when considering conversion to HD-SCS in patients with FBSS experiencing inadequate response to standard SCS.