A non-invasive spinal stimulation system controlled by hand movements enables people with paraplegia to regain stepping control.
The technique uses electrical signals from hand muscles to trigger magnetic stimulation of the lumbar spinal cord, allowing patients to initiate and control leg movements.
By performing rhythmic hand grips, participants with spinal cord injury were able to start and stop bilateral leg stepping, as well as control step length and cadence. Paraplegia is paralysis of the legs and lower body, typically caused by spinal cord damage.
Researchers from Tokyo Metropolitan Institute of Medical Science, led by Dr Yukio Nishimura in collaboration with Dr Toshiki Tazoe and colleagues, developed the closed-loop stimulation system. Closed-loop refers to a system that continuously monitors and responds to biological signals in real time.
The system works by recording electrical activity from hand muscles and converting these signals into trigger pulses for magnetic stimulation delivered to the lumbar region of the spine. The lumbar locomotor centre is the area of the spinal cord that controls walking movements.
Spinal cord injury above this centre disrupts communication between the brain and the spinal circuits controlling leg movements, resulting in paralysis. The new approach bypasses the injury site by creating an alternative pathway for control signals.
Ten individuals with chronic spinal cord injury participated in the study. All had injuries that prevented normal walking function, with damage located above the lumbar region.
The researchers observed progressive improvements with repeated use of the system. Stimulus-induced stepping became stronger over time, particularly in participants with thoracic spinal injuries, which occur in the middle section of the spine.
In participants with incomplete spinal cord injury, where some neural connections remain intact, voluntary stepping without stimulation also improved. This suggests the technique strengthens residual descending nerve pathways from the brain to the legs.
The non-invasive nature of the approach represents a significant advantage over existing treatments. Current options often require surgical implantation of electrodes, which carries risks and may not be suitable for all patients.
Because the technique requires no surgery, it offers a safer alternative for patients who cannot undergo invasive procedures due to medical contraindications or other health concerns.
The system enables users to maintain direct control over their stepping movements through voluntary hand actions. This differs from automated stimulation systems that operate independently of the user’s intentions.
Participants demonstrated the ability to modulate various aspects of their gait, including the timing of steps and the distance covered with each step. This level of control could prove crucial for navigating real-world environments.
The findings suggest that the technique works by strengthening preserved spinal circuits and any remaining connections between the brain and lower limbs. This dual mechanism may explain why improvements continued even when stimulation was not active.
The research team believes the approach could be developed into a practical rehabilitation tool for spinal cord injury patients. However, further studies will be needed to assess long-term effectiveness and optimal treatment protocols.
The technology could potentially benefit thousands of people living with paraplegia worldwide, offering hope for improved mobility without the risks associated with surgical intervention.
