VALSE: Integration of Neuromodulation and Exoskeleton Systems for Mobility in Individuals With Chronic Spinal Cord Injury

Spinal cord injury (SCI) disrupts communication between the brain and spinal cord below the lesion, often resulting in severe and permanent motor impairments. Despite advances in rehabilitation, recovery of walking remains limited and restoring mobility is consistently identified as a top priority by individuals living with SCI.

Epidural electrical stimulation (EES) of the spinal cord has emerged as a promising approach to restore movement after paralysis. By activating spinal motor circuits below the lesion, EES can enable standing, stepping, and walking in individuals with chronic SCI. ONWARD Medical has developed the ARC-IM spinal stimulation platform, which is currently being evaluated in several clinical studies, including BoxSwitch (NCT05942339), Think2Go (NCT06243952), and STIMO-BSI (NCT04632290).

In the BoxSwitch trial, optimized spatiotemporal EES protocols enabled participants with chronic SCI to perform standing, stepping, and walking movements. Building on these findings, the Think2Go and STIMO-BSI studies integrated the WIMAGINE implantable electrocorticography (ECoG) system developed by Clinatec (CEA, Grenoble, France) with spinal stimulation, creating a brain-spine interface capable of decoding motor intentions and translating them into spinal stimulation. These studies demonstrated that implantable brain-spine interfaces can restore voluntary control of lower-limb movements and support functional walking after severe paralysis.

Although these technologies have shown encouraging results, their use remains largely restricted to specialized rehabilitation settings. In parallel, robotic exoskeletons have been developed to support overground walking in individuals with SCI. The TWIICE exoskeleton is a lightweight and modular system specifically designed for use beyond rehabilitation centers and may complement spinal stimulation by providing functional support during walking.

In this study, the investigators will evaluate the preliminary safety and feasibility of the VALSE system, which combines the ARC-IM spinal cord stimulation platform with the TWIICE robotic exoskeleton in individuals with chronic traumatic SCI. Participants will be recruited from ongoing clinical studies at Lausanne University Hospital (CHUV), including BoxSwitch (NCT05942339), Think2Go (NCT06243952), and STIMO-BSI (NCT04632290), after completion of the relevant study phases.

As an early feasibility investigation, the study aims to generate preliminary safety and usability data on the combined use of spinal neuromodulation and robotic assistance during mobility tasks. The results will support the development of future neuroprosthetic solutions designed to improve walking ability, independence, and quality of life for people living with SCI.

Inclusion criteria

• Currently enrolled participants who have completed the relevant phase of their parent study at CHUV: BoxSwitch (NCT05942339, after the optimisation phase), Think2Go (NCT06243952, after the rehabilitation phase, or STIMO-BSI (NCT04632290, after the calibration and training phase of the optional extension with system upgrade),
• Must have a functional neuromodulation system,
• Must be at least 18 years old,
• Must be suffering from non-progressive traumatic spinal cord injury, sustained at least 12 months before signing the consent form,
• Must weigh less than 100 kg,
• Must have a standing height between 160 and 190 cm,
• Must be able to grasp and lift bilateral crutches in a seated position,
• Must have stable medical, physical and psychological condition as considered by the investigator,
• Must be able to understand and interact with the study team in French or English,
• Must agree to comply in good faith with all conditions of the study and to attend all scheduled appointments,
• Must provide Informed Consent as documented by signature prior to any study-related procedures.

Exclusion criteria

• Must not be diagnosed with severe osteoporosis/penia:

Dual Energy X-ray Absorptiometry (DEXA) results indicating a t-score below -3.5 at either the femoral neck or the total proximal femur.

Dual Energy X-ray Absorptiometry (DEXA) results indicating a bone mineral density (BMD) < 0.60 gm/cm2 at any knee region (distal femur, proximal tibia)

• Must not have deep vein thrombosis in lower extremities within the past 6 months.
• Must not have experienced lower extremity fractures within the last two years.
• Must not have current pressure ulcer of the arms, trunk, pelvic area, or lower extremities
• Must not present with a flexion contracture >15° at the hip or knee
• Must not have severe concurrent medical conditions that contraindicate moderate to intense exercise (e.g., uncontrolled hypertension, coronary artery disease, congestive heart failure).
• Must not have heterotopic ossification that impairs joint mobility
• Must not be implanted with a life-supporting medical device (devices implanted in the parent study are not considered life-supporting),
• Must not be pregnant,
• Must not be the investigator himself, his/her family members, employees, or other dependent persons.