Pilot Study to Evaluate Changes in Intra-Epidermal Nerve Fiber Density (IENFD) in Patients With Small-Fiber Neuropathy

This prospective observational pilot study will evaluate structural, functional, and patient-reported outcomes in adults with small fiber neuropathy who receive Saluda Evoke ECAP-controlled spinal cord stimulation as part of routine clinical care. The study does not assign, direct, or modify spinal cord stimulation therapy. All decisions regarding patient selection, trial stimulation, permanent implantation, and device programming are made independently by the treating physician according to standard clinical practice. The primary objective is to assess change in intra-epidermal nerve fiber density from baseline to 12 months. Secondary objectives include evaluation of quantitative sensory testing, pain intensity, patient-reported outcomes, and correlations between changes in nerve fiber density, sensory function, and neuropathic pain outcomes. The study will enroll up to 10 adult participants with clinically diagnosed small fiber neuropathy and chronic neuropathic pain. Research assessments include patient-reported outcome measures, quantitative sensory testing, review of available clinical records, and a 12-month follow-up skin biopsy for intra-epidermal nerve fiber density. This aligns with the approved protocol: observational, 10 adults, 12-month participant follow-up, primary IENFD endpoint, and secondary QST/pain/correlation endpoints.