Sarcopenia and related musculoskeletal phenotypes in patients considered for spinal cord stimulation: a scoping review.

Introduction: Musculoskeletal phenotype has not been systematically characterized in spinal cord stimulation research, although body habitus has occasionally been examined as a possible outcome modifier. Aim of study: To map the available evidence on sarcopenia, frailty, body composition, and related muscle-related variables in adults considered for or treated with spinal cord stimulation for chronic pain. Methods: This scoping review followed PRISMA-ScR guidance. PubMed/MEDLINE, Embase, and Scopus were searched from inception to 13 to 14 April 2026 without language restrictions. The search targeted spinal cord stimulation, chronic pain, and musculoskeletal phenotypes. Records were deduplicated by DOI, PMID, and normalized title. Title and abstract screening were performed independently by two reviewers. A formal risk-of-bias assessment was not conducted because the objective was evidence mapping rather than pooled-effect estimation. A descriptive appraisal of the study design and the definition of exposure was incorporated into the synthesis. Results: The searches identified 358 records. After removing 135 duplicate records, 223 records underwent title and abstract screening. Eleven full-text articles were assessed, and eight studies were included. No study diagnosed sarcopenia using consensus-based criteria. No study incorporated handgrip strength, gait speed, chair-stand testing, or dual-energy x-ray absorptiometry-derived lean mass - the standard tools recommended by current international consensus for sarcopenia diagnosis. The identified literature focused mainly on body mass index, obesity, and, in one study, psoas or iliopsoas-based imaging metrics. Two cohort studies reported less favorable outcomes with increasing body mass index, whereas two single-center series showed that severe or morbid obesity did not preclude technically successful treatment. One study suggested sex-specific associations between psoas-based measurements and selected pain or depression outcomes. Conclusion: Direct evidence on sarcopenia in spinal cord stimulation populations is absent. The current literature addresses body habitus more often than muscle phenotype and relies predominantly on body mass index, which cannot be used as a surrogate for sarcopenia. Future prospective cohorts should incorporate standardized measures of muscle strength, physical performance, and muscle quantity or quality.