Is There a Place for Spinal Cord Stimulation in the Management of Patients with Multiple Sclerosis? A Systematic Review of the Literature

Objective. Spinal cord stimulation (SCS) is a minimally invasive technique mainly used to treat neuropathic pain associated with failed back surgery syndrome. However, this therapy has been utilized to treat other chronic painful conditions, such as pain associated with multiple sclerosis (MS). Nonetheless, the efficacy of SCS in MS patients has not been fully established. In fact, in most of SCS series, MS patients represent only a subset of a bigger cohort which comprises different causes of pain, motor disorder, and other functional limitations. The aim of our study was to systematically review the literature to evaluate the effectiveness of SCS in MS patients. Methods. A literature search was performed through different databases (PubMed, Scopus, and Embase) using the following terms: "multiple sclerosis," "spinal cord stimulation," and "dorsal column stimulation," according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. Results. A total of 452 articles were reviewed, and 7 studies were included in the present analysis. 373 MS patients were submitted to a stimulation trial, and 82 MS patients underwent a de novo implantation. 285/373 (76.4%) of cases submitted to the SCS trial were enrolled for permanent stimulation. We found a long-lasting improvement in 193/346 (55.8%) MS patients with motor disorders, in 90/134 (67.13%) MS patients with urinary dysfunction, and in 28/34 (82.35%) MS patients with neuropathic pain. The efficacy of SCS was higher for urinary dysfunction (p = 0.0144) and neuropathic pain (p = 0.0030) compared with motor disorders. Conclusions. Our systematic review evidences that SCS is effective in MS patients. Urinary dysfunction and pain symptoms seem to be most responsive to SCS. Further studies are needed to improve the patient selection and clarify the best timing to perform SCS in these patients.