Long-Term Effectiveness of Spinal Cord Stimulation Beyond 24 Months: A PRISMA-ScR-Informed Scoping Review

Background/Objectives: Spinal cord stimulation (SCS) is an established therapy for chronic refractory pain, but its clinical value depends on whether benefit persists beyond the early post-implant period. Although short-term SCS studies are abundant, reports with follow-up of 24 months or longer are dispersed, methodologically heterogeneous, and difficult to interpret across indications and stimulation platforms. This scoping review aimed to map the clinical literature reporting SCS outcomes at ≥24 months, characterize the represented populations and modalities, summarize the long-term outcome domains assessed, and identify major methodological and clinical gaps in the evidence base. Methods: This PRISMA-ScR-informed scoping review applied a Population-Concept-Context framework. PubMed/MEDLINE and Scopus were searched through April 2026, yielding 6866 records before deduplication. Following staged title/abstract screening, iterative full-text retrieval, and the reconciliation of overlapping publications, 292 unique full-text reports were assessed for eligibility. Studies reporting original clinical SCS data with extractable outcomes at ≥24 months were included. No meta-analysis or formal GRADE assessment was undertaken, as the objective was evidence mapping rather than pooled effect estimation. Results: The final evidence map comprised 65 unique reports representing a cumulative report-level population of 11,518 participants across non-overlapping cohorts. The literature was dominated by non-randomized evidence (55 observational reports; 10 randomized or randomized-derived). The most frequent indication was mixed chronic pain (30/65; 46.2%), followed by failed back surgery syndrome/persistent spinal pain syndrome (FBSS/PSPS; 16/65; 24.6%), chronic back and/or leg pain (6/65; 9.2%), complex regional pain syndrome (CRPS; 5/65; 7.7%), and painful diabetic neuropathy (PDN; 4/65; 6.2%). Most reports involved conventional or unspecified SCS (47/65; 72.3%), with smaller contemporary clusters for 10 kHz high-frequency SCS and ECAP-controlled closed-loop SCS. The most frequently reported outcome domains were pain durability, function and quality of life, device-related outcomes, and opioid use. At a descriptive level, the literature more often supported persistence of benefit than complete erosion of effect, particularly in spinal pain populations and in contemporary PDN and closed-loop SCS cohorts. Interpretation was constrained by outcome heterogeneity, cohort overlap, mixed indication categories, and inconsistent opioid and device-maintenance reporting. Conclusions: The long-term SCS literature supports the view that durable benefit is achievable in a substantial patient subset, particularly in FBSS/PSPS populations, and in more recent evidence, in PDN, nonsurgical refractory back pain, and closed-loop SCS cohorts. The evidence base remains heterogeneous and does not support a uniform certainty-ranked estimate across indications and technologies. Future studies should prioritize indication-specific cohorts, standardized multidomain outcome reporting, and transparent separation of unique cohorts from secondary analyses of the same clinical populations.