The goal of this clinical trial is to evaluate whether non-invasive spinal cord neuromodulation with the SCONE™ device can improve upper limb function in people with multiple sclerosis. The study will investigate if combining SCONE™ therapy with rehabilitation exercises leads to improvements in arm and hand movement, and whether the therapy is safe and well tolerated in this patient population. Participants will receive non-invasive spinal cord stimulation with the SCONE™ device and perform rehabilitation exercises specifically focused on the upper limb.

This is a pilot, randomized, placebo-controlled study designed to evaluate the efficacy and safety of transcutaneous spinal cord stimulation (tSCS) in improving upper limb function in patients with Multiple Sclerosis (MS).

tSCS is a non-invasive neuromodulation technique that delivers low-intensity electrical impulses through the skin to specific spinal segments. This external stimulation aims to enhance spinal excitability and restore communication between the brain and spinal circuits affected by MS. Previous research in spinal cord injury has demonstrated functional improvements in motor performance with tSCS, suggesting its potential benefit in MS-related disability.

In this study, participants with clinically confirmed MS and upper limb impairment will first undergo a 6-week period of standard occupational therapy. After this run-in phase, they will be randomly assigned in a 1:1 ratio to receive either active tSCS or sham stimulation for an additional 6 weeks, while continuing occupational therapy. The intervention will be delivered at the rehabilitation center of Hospital de la Esperanza, in a seated position, using surface electrodes placed at the posterior cervical region. Sessions will last approximately 30 minutes, three times per week (preferably Monday, Wednesday, and Friday).

The sham condition will mimic the procedure using the same equipment and electrode placement but without delivering effective stimulation. After completion of the blinded phase, participants originally randomized to sham will be offered the opportunity to receive active tSCS in an open-label extension.

The primary efficacy endpoint is improvement in upper limb function, assessed by the Nine-Hole Peg Test (9HPT). Secondary endpoints include the Action Research Arm Test (ARAT), patient-reported outcomes (NeuroQOL - Upper Extremity Function, Modified Fatigue Impact Scale [MFIS], and Global Impression of Change [GIC]), and clinical safety measures.

tSCS is generally safe and well-tolerated. Reported side effects are typically mild and transient, including tingling, skin irritation, or muscle discomfort. Participants will be monitored throughout the study, and adverse events will be recorded.

This pilot trial will provide preliminary data on the clinical utility of tSCS in MS and inform the design of larger randomized controlled trials.

Inclusion Criteria:

• Age between 18 and 70 years.
• Diagnosis of Multiple Sclerosis (according to revised McDonald criteria).
• Upper limb dysfunction (9-Hole Peg Test score ≥ 20% slower than normative values).
• Stable disease-modifying treatment for ≥ 6 months before enrollment.
• Expanded Disability Status Scale (EDSS) score between 3.0 and 6.5.
• Ability to provide informed consent.

Exclusion Criteria:

• Relapse or corticosteroid treatment within the last 3 months.
• Severe spasticity of the upper limb (Modified Ashworth Scale > 3).
• Implanted electrical devices (pacemaker, spinal cord stimulator).
• Epilepsy or uncontrolled seizures.
• Severe psychiatric disorders or cognitive impairment interfering with study procedures.
• Pregnant or breastfeeding women.
• Participation in another interventional clinical trial within the last 3 months.

De-identified individual participant data (IPD) that underlie the results reported in future publications will be shared. This will include baseline characteristics, efficacy outcomes, and safety data.

IPD and supporting documents will be available within 12 months after publication of the main results and will remain available for a minimum of 5 years thereafter.

Access will be granted to qualified researchers with a sound scientific proposal for secondary analyses related to multiple sclerosis or neuromodulation. Requests will be reviewed by the study steering committee. Data will be shared through a secure data-sharing platform after signing a data access agreement to ensure confidentiality and appropriate use.