Closed-loop Spinal Cord Stimulation for Chronic Pain: A Systematic Review and Meta-Analysis

Spinal cord stimulation (SCS) is an established option for managing neuropathic pain; however, open-loop systems deliver fixed stimulation that may lead to variable efficacy. Closed-loop SCS, which uses evoked compound action potentials (ECAPs) to adjust stimulation in real time, may provide more consistent and superior pain relief. Our objective is to systematically review and meta-analyze the efficacy, safety, and functional outcomes of ECAP-controlled CL-SCS in adults with chronic pain.

A systematic search of PubMed, Embase, Cochrane Central Register of Controlled Trials, and Scopus identified randomized controlled trials and observational studies evaluating ECAP-based CL-SCS. The primary outcome was overall pain response (≥50% relief). Secondary outcomes included high pain response (≥80%), functional improvement, quality-of-life (QoL) enhancement, opioid reduction, sleep improvement, patient satisfaction, and adverse events. Pooled prevalence was calculated using random-effects single-arm meta-analysis.

Seven studies (453 patients) were included, with follow-up ranging from 4.5 days to 36 months. Pooled rates were overall pain response 90% (95% CI: 79.0-97.0), high pain response 57% (41.0-72.0), functional improvement 90% (74.0-99.0), QoL improvement 84% (75.0-92.0), opioid reduction or elimination 77% (49.0-97.0), sleep improvement 66% (54.0-77.0), and patient satisfaction 98% (91.0-100.0). Serious adverse events were rare, and most complications were mild and device related. Heterogeneity was high for most outcomes, except QoL and opioid reduction or elimination.

ECAP-controlled CL-SCS provides high and consistent rates of pain relief, functional and QoL improvements, and patient satisfaction, with an acceptable safety profile. Benefits include reduced use of opioids and improved sleep. Larger, long-term, and health economics studies are needed to optimize programming parameters and guide broader implementation.