BCI-Assisted SCS-EXS for Gait Optimization

Inclusion Criteria: * Age 14-65 years, any gender. * Clinical diagnosis of spinal cord injury (SCI) due to trauma, inflammation, tumor, vascular disease, or iatrogenic factors, confirmed by medical history, physical examination, and ancillary tests, resulting in lower limb motor dysfunction. * SCI diagnosed ≥6 months prior, with ≥1 month of continuous conventional rehabilitation (e.g., physical therapy, acupuncture, hydrotherapy, ≥3 hours daily) without significant improvement in motor function in the past 2 months. * ASIA Impairment Scale (AIS) grade A, B, or C based on the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI). * Good general health with a life expectancy ≥12 months. * Mini-Mental State Examination (MMSE) score ≥22. * Educational attainment of secondary school or above. * Willingness to participate, provide informed consent, and comply with study follow-up. Exclusion Criteria: * Presence of diseases other than spinal cord injury (SCI) that affect lower limb motor function, including brain diseases (e.g., brain tumor, stroke), lower limb vascular diseases (e.g., lower limb vascular occlusion), peripheral nerve diseases, or lower limb bone diseases (e.g., osteoarthritis, joint contracture). * Requires continuous medical interventions (e.g., tracheal intubation, nasogastric feeding) to maintain critical physiological functions (e.g., heartbeat, respiration, swallowing). * Congenital or acquired structural abnormalities of the lower limb bones or muscles. * Presence of surgical contraindications (e.g., anesthesia-related adverse reactions, coagulation risks, or surgeon's determination of unsuitability for surgery). * Presence of active implantable devices except for SCS or BCI devices (e.g., pacemakers, defibrillators, drug infusion pumps, cochlear implants, sacral nerve stimulators). * Unable to receive implantable devices due to other disease treatments or investigations, or requires magnetic resonance imaging (MRI) during the device implantation period. * MRI shows structural damage \>50% in motor function areas (precentral and postcentral gyri, ventromedial sensorimotor areas, mid temporal lobe, Broca's area, Wernicke's area, Geschwind's area), or DTI shows damage \>50% in the posterior limb of the internal capsule. * Severe cardiovascular disease: Above level II myocardial ischemia or myocardial infarction, uncontrolled arrhythmias (including QTc interval ≥450 ms in men, ≥470 ms in women), level III-IV heart failure (NYHA classification), or echocardiography showing LVEF \<50%. * Coagulation abnormalities (INR \>1.5 ULN, PT \>ULN +4 s, or APTT \>1.5 ULN), hemorrhagic tendency, or undergoing thrombolytic or anticoagulant therapy. * Severe infections within 4 weeks before surgery (requiring IV antibiotics, antifungals, or antivirals) or lumbar soft tissue infections, or unexplained fever \>38.5℃ during screening or before surgery. * HIV infection, acquired immunodeficiency syndrome (AIDS), active tuberculosis, active hepatitis B (HBV DNA ≥500 IU/ml), hepatitis C (positive HCV antibody and detectable HCV-RNA), or co-infection of hepatitis B and C. Severe cerebrovascular events (including transient ischemic attack, cerebral hemorrhage, cerebral infarction), deep vein thrombosis, or pulmonary embolism within 12 months before enrollment. * Metastatic malignancies or untreated malignant tumors. * Major surgery or severe traumatic injuries, fractures, or ulcers within 4 weeks before enrollment. * Addictive habits such as drug abuse or alcoholism. * History of psychotropic drug abuse that is not controllable or presence of mental disorders, including major psychiatric illnesses (e.g., depression \[BDI score \>20\], anxiety, obsessive-compulsive disorder, schizophrenia, autism, chronic sleep disorders, consciousness disorders). * Pregnant, breastfeeding, planning to conceive, or women of childbearing potential without reliable contraception. * Participation in other clinical trials within the past month. * Cognitive impairments or poor compliance from subjects, family members, or caregivers, or inability to complete at least 12 months of follow-up and rehabilitation training. * Other conditions that increase the risk of study participation or device use, as determined by the investigator.