Rehabilitation Combining Spatiotemporal Spinal Cord Stimulation and Real-time Triggering Exoskeleton After Spinal Cord Injury

Combinative Rehabilitation Strategy Combining Spatiotemporal Spinal Cord Stimulation and Real-time Triggering Exoskeleton (SCS-EXS) After Spinal Cord Injury: An Exploratory Study

Spinal cord injury (SCI) can be caused by trauma, inflammation, tumors, and other factors, often leading to issues such as impaired leg movement, abnormal sensation, and difficulties with bladder and bowel control. These challenges significantly affect the patient's quality of life. While there is currently no cure for spinal cord injury, the latest guidelines recommend spinal cord stimulation and robotic exoskeletons as effective rehabilitation methods.

Spinal cord stimulation (SCS) involves implanting a device that delivers electrical stimulations to aid in motor function recovery. Its safety and effectiveness have been proven in multiple clinical studies. For example, in 2022, a Swiss research team successfully helped three patients with severe spinal cord injuries regain the ability to stand, walk, and perform other movements, offering new hope for recovery.

A robotic exoskeleton is a wearable device that assists patients in movements like walking while promoting nerve and muscle recovery. This technology has become an increasingly important tool in spinal cord injury rehabilitation.

Recent studies have shown that combining spinal cord stimulation and robotic exoskeletons yields better outcomes. For instance, in 2023, an American research team demonstrated that after 24 weeks of combined therapy, patients could achieve independent walking or walk with the aid of assistive devices.

This study aims to combine spinal cord stimulation with robotic exoskeleton therapy to develop personalized rehabilitation plans for patients. The goal is to restore lower limb motor function and improve long-term quality of life.

Spinal cord injury (SCI) often results in long-term impairments in motor, sensory, and autonomic nervous functions, significantly reducing patients' quality of life and increasing the burden on families and society. Spinal cord stimulation (SCS) has emerged in recent years as a key therapeutic tool for functional rehabilitation following SCI. Multiple clinical research has confirmed its safety and effectiveness. Chalif et al. evaluated the applications of SCS in managing chronic SCI in a systematic review, highlighting its potential not only for motor function rehabilitation but also for improving bladder and bowel functions, regulating respiratory pressures, and enhancing gastrointestinal motility.

On the other hand, robotic exoskeleton as an innovative rehabilitation device, has demonstrated great potential in the treatment of SCI. By providing mechanical support, robotic exoskeletons assist patients in movement training, thereby promoting neural recovery and strengthening muscle function. Numerous clinical studies have investigated the benefits of exoskeleton training for lower limb rehabilitation in SCI patients, with results showing significant improvements in walking speed and independence. Future studies should explore the combination of exoskeleton training with other rehabilitation modalities to optimize outcomes and provide more robust clinical guidance.

The combination of SCS and robotic exoskeletons represents a novel direction in motor recovery for SCI. This approach aims to activate spinal neurons via SCS to restore muscle and neural functions, while robotic exoskeletons offer gait support and assist in motor activities, providing sensory feedback to construct a complete motor-sensory loop. This combination also holds promise for spinal circuit reorganization following SCI. Gorgey et al. reported three cases in 2020 and 2023 involving epidural spinal cord stimulation (eSCS) combined with exoskeleton training. The researchers identified optimal muscle activation parameters for walking and conducted 24 weeks of gait training with concurrent stimulation and exoskeleton use, achieving enhanced rehabilitation outcomes through this synergistic approach.

Currently, research on the combination of SCS and robotic exoskeletons for lower limb rehabilitation is limited. There is a lack of large-scale, long-term studies to validate the sustained efficacy of this combined approach. To address this gap, our study aims to develop an innovative rehabilitation system combining spatiotemporal spinal cord stimulation with real-time triggering exoskeleton. This research seeks to integrate the two systems clinically, assess their safety and effectiveness, and design personalized strategies to maximize patients' rehabilitation outcomes.

Inclusion Criteria:

• Aged between 14 and 65 years, with no restriction on gender;
• Diagnosed with spinal cord injury resulting in lower limb motor impairment due to trauma, inflammation, tumors, vascular diseases, iatrogenic factors, or other causes, confirmed through medical history, physical examination, and auxiliary tests;
• Diagnosed with spinal cord injury for at least 6 months, undergoing continuous routine rehabilitation for at least 1 month (including but not limited to physical therapy, acupuncture, hydrotherapy, etc., with daily training time ≥ 3 hours), but with no significant improvement in motor function over the past 2 months;
• Classified according to the ASIA impairment scale (AIS) based on the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI), with an impairment grade of A, B, or C;
• Generally in good health, with an expected life expectancy of ≥ 12 months;
• The subject voluntarily agrees to participate in the study, signs an informed consent form, demonstrates good compliance, and is willing to cooperate with follow-up assessments.

Exclusion Criteria:

• Suffering from other diseases affecting lower limb muscle function besides spinal cord injury, including brain diseases (such as brain tumors, stroke, etc.), lower limb vascular diseases (such as lower limb vascular occlusion), peripheral nerve diseases, lower limb bone diseases (such as osteoarthritis, joint contractures, etc.);
• Congenital or acquired abnormalities in lower limb skeletal or muscular structure;
• Presence of surgical contraindications (such as adverse reactions to anesthesia, bleeding risks, or when the surgeon deems the patient unsuitable for surgery);
• Presence of active implanted devices, such as a pacemaker, defibrillator, drug infusion pump, cochlear implant, sacral nerve stimulator, etc. (whether turned on or off);
• Unable to undergo implantation of active devices due to treatment or examination requirements for other diseases;
• Suffering from severe cardiovascular diseases: ischemic heart disease or myocardial infarction of class II or higher, uncontrolled arrhythmias (including QTc interval ≥450 ms for males or ≥470 ms for females); heart failure of NYHA class III-IV, or echocardiogram showing left ventricular ejection fraction (LVEF) <50%;
• Coagulation dysfunction (INR >1.5 ULN or PT >ULN +4 seconds or APTT >1.5 ULN), bleeding tendency, or currently receiving thrombolytic or anticoagulant therapy;
• Severe infection within 4 weeks prior to surgery (such as requiring intravenous antibiotics, antifungals, or antivirals) or soft tissue infection in the lumbar or back region, or unexplained fever >38.5°C during screening or before surgery;
• Human Immunodeficiency Virus (HIV) infection or known acquired immunodeficiency syndrome (AIDS), active pulmonary tuberculosis, active hepatitis B (HBV DNA ≥500 IU/ml), hepatitis C (positive hepatitis C antibody, and HCV-RNA levels above the detection threshold), or co-infection with both hepatitis B and C;
• Severe cerebrovascular events (including transient ischemic attacks, intracerebral hemorrhage, or ischemic stroke), deep vein thrombosis, or pulmonary embolism within 12 months prior to enrollment;
• Presence of metastatic malignant tumors or untreated malignant tumors;
• Major surgery or severe traumatic injury, fractures, or ulcers within 4 weeks prior to enrollment;
• Presence of addictive behaviors such as drug abuse or alcoholism;
• History of substance abuse of psychiatric drugs that cannot be discontinued, or presence of mental disorders;
• Pregnant women, breastfeeding women, women planning pregnancy, or women of childbearing age without reliable contraception;
• Presence of cognitive impairments or other factors preventing the patient from following treatment interventions and rehabilitation training;
• Situations that increase the risk associated with participation in the study or the study devices, and other conditions judged by the investigator that would make the patient unsuitable for inclusion in the study.