Spinal Cord Stimulation for Poststroke Spasticity

Post-stroke spasticity is a common disabling complication of ischemic or hemorrhagic stroke. It can lead to abnormal muscle tone, restricted joint movement, impaired motor function, pain, and reduced independence in daily activities. Current treatments include rehabilitation therapy, oral antispastic medications, and botulinum toxin injections, but some patients continue to have clinically significant spasticity despite these treatments. Spinal cord stimulation (SCS) is a neuromodulation technique that delivers electrical stimulation to the spinal cord and may help regulate abnormal spinal motor circuits and reduce spasticity.

Previous exploratory studies have suggested that SCS may reduce limb spasticity and improve muscle strength, motor coordination, and functional movement after stroke. However, the available evidence is mainly based on small or exploratory studies, and the safety and efficacy of SCS for post-stroke spasticity have not yet been confirmed in a large, randomized, sham-controlled clinical trial. Therefore, a well-designed controlled study is needed to determine whether the observed improvements are caused by active SCS and to further evaluate device-related safety.

The Spinal Cord Stimulation for Post-Stroke Spasticity study (SCS-PSS study) is a prospective, multicenter, double-blind, randomized, sham-controlled clinical trial designed to evaluate the safety and efficacy of an implanted SCS system for adults with post-stroke spasticity. The study will enroll 92 participants with stable unilateral upper- or lower-limb spasticity after ischemic or hemorrhagic stroke who have not achieved their treatment goals with previous treatments. All participants will undergo implantation of an SCS system and will then be randomized in a 1:1 ratio to receive either active SCS or sham SCS during the first 6 weeks after randomization. Participants will attend a postoperative visit within 3 to 7 days for active or sham device activation, programming, safety assessment, and study evaluations. At 6 weeks after randomization, all participants will receive active stimulation and will continue follow-up through 24 weeks. In addition, they will undergo long-term follow-up for up to 2 years to further evaluate the durability of treatment effects and the long-term safety of the implanted SCS system. The primary outcome is the change from baseline to 6 weeks after randomization in the mean Modified Ashworth Scale score of primary target muscle groups. Additional outcomes include joint range of motion, motor function, walking ability, functional independence, pain, quality of life, adverse events, serious adverse events, and device deficiencies.

Inclusion criteria

• Aged ≥18 years and <75 years, regardless of sex;
• Diagnosed with ischemic or hemorrhagic stroke, with unilateral or single-limb motor dysfunction persisting for at least 6 months;
• The primary brain lesion and its underlying cause are clinically stable;
• Presence of unilateral upper- or lower-limb spasticity, with a Modified Ashworth Scale (MAS) grade of ≥2 in at least two muscle groups of the affected limb;
• Post-stroke limb dysfunction has not reached the treatment goal despite previous interventions, such as physical therapy and oral medications, and the participant's condition has shown no recent improvement;
• The type and dose of existing rehabilitation therapy and oral antispastic medications must remain unchanged during the study;
• Willing and able to complete all study visits and procedures;
• Able to understand the study and provide written informed consent.

Exclusion criteria

• Any contraindication to spinal cord stimulation surgery;
• Uncontrolled refractory epilepsy;
• Presence of tonic spasticity, such as decorticate rigidity or decerebrate rigidity;
• Poorly controlled severe psychiatric or cognitive impairment, defined as a Beck Depression Inventory-II score >25 or a Mini-Mental State Examination score <24;
• Active systemic infection;
• Presence of an implanted neurostimulator or drug delivery system;
• Botulinum toxin treatment within 4 months before enrollment;
• Plans to initiate any new treatment during the study that may affect limb movement, including chemical denervation therapies (such as botulinum toxin), oral antispastic medications, surgical procedures (such as peripheral neurotomy or contralateral C7 nerve transfer), or other physical therapy interventions;
• Pregnancy, breastfeeding, or planned pregnancy during the study;
• The participant or family is unable or unwilling to participate in long-term SCS treatment management;
• Participation in another clinical study within 4 weeks before signing informed consent;
• Any other condition that, in the investigator's judgment, makes the individual unsuitable for participation in the study.