Spinal cord stimulation for paralysis

In plain language

After a spinal cord injury, the nerves below the injury can still work, but the signals from the brain no longer reach them reliably. Spinal cord stimulation sends small electrical pulses to the lower back or neck to make the nerves that control the legs, trunk, or arms easier to switch on. When the stimulation is timed to a person's own attempts to move, researchers think the spinal circuits may carry more of the work, and some people regain movement that they did not have before.

There are two main approaches. Epidural systems place electrodes surgically on the surface of the spinal cord or its nerve roots, which gives precise control but needs an implant. Transcutaneous systems place electrodes on the skin over the spine and need no surgery, though the signal is less focused. Early results in very small groups look encouraging, but the effects vary between people and the long-term benefit is still being studied.

Technical explanation

Epidural stimulation delivers current through multi-contact paddle leads placed over the dorsal roots or dorsal columns at lumbosacral or cervical levels. Rowald and colleagues (2022) tested a new paddle lead designed to target the dorsal roots that control leg and trunk movement, with its placement guided by computational modelling. In three people with complete sensorimotor paralysis, activity-specific stimulation programmes enabled standing, walking, cycling, swimming and trunk control within a single day. Wagner and colleagues (2018) used an implanted pulse generator that delivered stimulation timed to intended movement, in people with chronic spinal cord injury who had been injured more than four years earlier. Press coverage reports three participants, and describes voluntary control of previously paralysed muscles improving over about five months of training and persisting when stimulation was switched off.

Transcutaneous stimulation applies surface electrodes over the spine. The Up-LIFT trial (Moritz and colleagues, 2024) studied ARCEX Therapy, a non-invasive system designed to improve arm and hand function in chronic tetraplegia. It was a single-arm, open-label study with 65 enrolled participants and 60 in the primary effectiveness analysis. The authors report that 43 of 60 participants (71.7%) met the criteria for responders in both strength and function, and that this met the primary effectiveness endpoint. No serious adverse events were judged related to the therapy. The design had no concurrent control group and no sham stimulation, so the size of the effect compared with rehabilitation alone is uncertain.

What the evidence says

Each statement is typed by the strength of its evidence and linked to the source that supports it.

Limitations and open problems

• The Up-LIFT trial was single-arm and open-label with no sham group, so the gains cannot be fully separated from rehabilitation alone (Moritz and colleagues, 2024).
• The authors cannot exclude that the rehabilitation period before stimulation alone improved responses, and the therapy period was a pre-specified two months, so the trial does not show how long the benefit lasts (Moritz and colleagues, 2024).
• Epidural results come from very small groups of three participants each, so they cannot yet show how well the approach works across the wider spinal cord injury population (Rowald and colleagues, 2022; Wagner and colleagues, 2018).
• The authors state that the mechanisms behind the improvements still need to be explored (Moritz and colleagues, 2024).
• The Up-LIFT trial was sponsored by ONWARD Medical, and several investigators hold patents, act as consultants to the company or may hold shares in it (Moritz and colleagues, 2024).
• The company states that the non-invasive system is cleared for incomplete injuries only, and the sources reviewed did not identify a comparable clearance for complete injuries.

Possible future uses

Product concepts: Neural bypass for hand function after injury

Timeline

1. 31 Oct 2018Wagner and colleagues report in Nature that stimulation timed to intended movement restores walking in people with chronic spinal cord injury. Sources: [3], [4]
2. 7 Feb 2022Rowald and colleagues report in Nature Medicine that a new epidural lead restored trunk and leg control in three people with complete paralysis. Sources: [2]
3. 2 Apr 2024ONWARD Medical announces that it has submitted a De Novo application to the FDA for the ARC-EX system, with upper-limb function as the first indication. Sources: [5]
4. 20 May 2024Moritz and colleagues publish the Up-LIFT pivotal trial of non-invasive spinal cord stimulation for arm and hand function in Nature Medicine. Sources: [1]

Futures this could help bring about

How far away?

Walking again after spinal cord injury

Engineering prototypes · 4 of 6 steps done

Related breakthroughs

• Ten people with chronic spinal cord injury show gains in strength and balance over one year (25 Feb 2025)

Glossary

Epidural stimulation

Electrical stimulation delivered by electrodes placed on the outer surface of the spinal cord or nerve roots, inside the spinal canal.

Transcutaneous stimulation

Electrical stimulation delivered through electrodes placed on the skin, without surgery.

Tetraplegia

Partial or complete paralysis of the arms, trunk and legs, caused by injury to the cervical (neck-level) spinal cord.

Responder (Up-LIFT)

A participant who met the Up-LIFT responder criteria for both strength and function.

Sources

1. peer reviewed paper
   Non-invasive spinal cord electrical stimulation for arm and hand function in chronic tetraplegia: a safety and efficacy trial
   Chet Moritz, Edelle C. Field-Fote, Candace Tefertiller et al.. Nature Medicine, 20 May 2024. DOI: 10.1038/s41591-024-02940-9. Accessed 21 Oct 2026.
2. peer reviewed paper
   Activity-dependent spinal cord neuromodulation rapidly restores trunk and leg motor functions after complete paralysis
   Andreas Rowald, Salif Komi, Robin Demesmaeker. Nature Medicine, 7 Feb 2022. DOI: 10.1038/s41591-021-01663-5. Accessed 21 Oct 2026.
3. peer reviewed paper
   Targeted neurotechnology restores walking in humans with spinal cord injury
   Fabien B. Wagner, Jean-Baptiste Mignardot, Camille G. Le Goff-Mignardot et al.. Nature, 31 Oct 2018. DOI: 10.1038/s41586-018-0649-2. Accessed 21 Oct 2026.
4. news
   Breakthrough in treating paralysis
   ScienceDaily, 1 Nov 2018. Accessed 21 Oct 2026.
5. news
   ONWARD Medical Submits De Novo Application to FDA for its ARC-EX System
   Santelog, 2 Apr 2024. Accessed 21 Oct 2026.
6. company announcement
   ARC-EX (ARCEX System) product information
   ONWARD Medical, 21 Oct 2026. Accessed 21 Oct 2026.

Revision history

3 changes since this profile was created.