Tag: spinal cord injury

  • Spinal Cord Stimulation in 2026: How Electrical Implants Are Helping Paralyzed Patients Walk Again

    In 2022, a team led by Grégoire Courtine at the Swiss Federal Institute of Technology published a paper in Nature that identified the specific neurons responsible for restoring walking after paralysis. They called them SCVsx2::Hoxa10 neurons—a population of cells in the lumbar spinal cord that, when activated by epidural electrical stimulation combined with rehabilitation, orchestrated the recovery of walking in nine individuals with chronic spinal cord injury. When the researchers optogenetically silenced these neurons in mice, walking stopped instantly. When they reactivated them, walking resumed immediately. The paper didn’t just show that spinal cord stimulation works. It showed which neurons it works through—a mechanistic explanation for a result that had previously looked like something between a miracle and an engineering trick.

    That result sits at the center of a field that has moved, in under a decade, from “we got a paralyzed person to twitch their leg” to “we got a completely paralyzed person to walk, cycle, swim, and climb stairs within 24 hours of turning on the stimulator.” The technology isn’t a cure. It doesn’t repair the severed spinal cord. But it’s the closest thing to functional restoration that exists for the roughly 250,000 to 500,000 people worldwide who sustain spinal cord injuries each year.

    How the spinal cord works (and what happens when it breaks)

    Your brain doesn’t directly control your legs. It sends high-level movement commands—”walk,” “stand,” “step over that obstacle”—down the spinal cord, where local neural circuits called central pattern generators translate those commands into the precise, rhythmic sequences of muscle activation that produce coordinated movement. The spinal cord below the injury site isn’t dead tissue. The pattern generators, the motor neurons, the sensory circuits—they’re all intact. They’re just disconnected from the brain. A spinal cord injury is less like cutting a power cable and more like cutting the communication line between a command center and a factory that’s still fully staffed and operational.

    This is why epidural electrical stimulation works. A thin array of electrodes, implanted on the surface of the spinal cord below the injury site, delivers patterned electrical pulses that mimic the signals the brain can no longer send. The electrodes activate the dorsal roots—the sensory nerve fibers that enter the spinal cord from the body—which in turn excite the spinal circuits that coordinate movement. The stimulator doesn’t replace the brain. It substitutes for the broken communication link, providing enough activation to the intact spinal circuitry below the injury to enable the pattern generators to do what they were designed to do.

    What patients can actually do

    The results have escalated quickly. In 2018, patients with incomplete spinal cord injuries—some residual sensation or movement below the injury—were able to walk and cycle with epidural stimulation. Courtine’s 2022 Nature Medicine paper pushed further: three patients with complete paralysis—no voluntary movement, no sensation below the injury—could take steps on a treadmill within the first day of turning on the stimulator. One climbed stairs. All could swim, cycle, and perform leg presses. A biomedical engineer at the University of Alberta who reviewed the results called it “a big deal.”

    A 2025 case study from Italian researchers at the MINE Lab and EPFL documented the first successful application of epidural stimulation in a patient with a lower thoracic spinal cord injury involving the conus medullaris—the tapered lower end of the spinal cord. Previous trials had excluded these patients, who represent over half of thoracic spinal cord injuries, because of concerns about damaging the nerve roots that control the legs. The patient progressed from being unable to walk to covering one kilometer independently with a walker within six months of the implant. A 2025 paper in Science Translational Medicine showed that high-frequency epidural stimulation reduced spasticity—the involuntary muscle contractions that plague roughly 70 percent of spinal cord injury patients—enabling rehabilitation protocols that further improved recovery.

    A systematic review published in 2024 analyzed 64 studies encompassing 306 patients and found improvements in motor function, cardiovascular regulation, pulmonary function, bladder and bowel control, and genitourinary function. The effects extend well beyond walking. Spinal cord stimulation is restoring autonomic functions—blood pressure regulation, temperature control, sexual function—that most people don’t associate with paralysis but that profoundly affect quality of life.

    The gap between demonstration and daily life

    The results are genuine. The caveats are significant.

    First, the stimulator must be on for the abilities to exist. Turn it off, and the paralysis returns. Some patients have shown neural adaptation over months or years of stimulation combined with rehabilitation—one participant in a 2017 study progressively recovered voluntary leg movement and standing without stimulation over 3.7 years of training—but this is the exception. For most patients, the device is a permanent prosthetic, not a temporary bridge to recovery.

    Second, the current interface is cumbersome. Users select their desired movement on a tablet, which sends Bluetooth commands to a transmitter worn around the waist. The transmitter must be positioned next to a pulse generator implanted in the abdomen, which activates the electrode array on the spine. Courtine’s team is developing a next-generation system, but the current version requires conscious selection of each movement type before execution. You don’t just decide to walk. You tell the tablet you want to walk, the tablet tells the transmitter, the transmitter tells the implant, and the implant activates the pattern that produces walking. The latency and cognitive overhead are nontrivial.

    Third, weight support matters. The patients who stepped within 24 hours did so in harnesses that supported more than half their body weight. The one-kilometer walk with a walker at six months is a more representative picture of functional use than the headline-grabbing first-day stepping videos. And patients with paralysis are at elevated risk for osteoporosis and fragility fractures—bones that haven’t borne weight for years break under loads that healthy bones absorb without issue.

    Fourth, the technology doesn’t work equally well for everyone. Severity of the original injury, time elapsed since injury, location of the damage, and the individual patient’s residual neural architecture all affect outcomes. A 2025 study of 11 patients with incomplete injuries found that spasticity improved in all 11, sensation recovered in 10, but only 4 of 11 showed improved lower limb strength. The field is still identifying which patients benefit most and why.

    Where it’s heading

    The next frontier is closed-loop stimulation—systems that read neural signals from the spinal cord or brain in real time and adjust stimulation parameters automatically, rather than relying on preset patterns selected through a tablet. A 2026 case report from Zhejiang University described a closed-loop spinal neural interface combined with rehabilitation for incomplete spinal cord injury, representing early steps toward systems that adapt to the patient’s intent rather than executing fixed programs.

    Intraspinal microstimulation—tiny electrodes inserted directly into the spinal cord rather than placed on its surface—offers potentially more precise and selective muscle activation. A 2026 study in Scientific Reports described the first fully implantable intraspinal microstimulation device tested in a large animal model with spine dimensions similar to humans, moving toward clinical translation.

    The broader trajectory: epidural stimulation combined with rehabilitation is progressing from proof-of-concept in research labs to clinical feasibility studies to, eventually, regulated medical devices available to the hundreds of thousands of people living with spinal cord injuries worldwide. The International Neuromodulation Society has published consensus guidance on the safety of epidural stimulation, noting it is “a generally safe, minimally invasive procedure.” The infrastructure for clinical translation is being built.

    Courtine’s lab identified the neurons. The Italian team proved it works in injuries previously considered untreatable. The spasticity reduction data from Science Translational Medicine demonstrated benefits beyond motor recovery. The systematic reviews have established the evidence base. What remains is the engineering work of making the system smaller, smarter, more responsive, and cheap enough to deploy at the scale the patient population requires—the same progression from laboratory demonstration to clinical reality that every neuroprosthetic technology follows, measured in years, not months.

    We cover spinal cord stimulation alongside brain-computer interfaces, retinal implants, and the full landscape of neuroprosthetic technology across our Neuroprosthetics course—including why the spinal cord below an injury isn’t a broken machine waiting for repair. It’s a working machine waiting for a signal.

  • Can Brain-Computer Interfaces Restore Movement After Paralysis? The Current Evidence

    There is a man with ALS who has been using a brain-computer interface at home, independently, for over two years. Four microelectrode arrays sit in his left motor cortex, recording from 256 electrodes. He uses the system to control his personal computer—typing, browsing, communicating—through a multimodal BCI that decodes both his attempted speech into text and his attempted hand movements into cursor movements and clicks. In structured tests, the system is 99 percent accurate at outputting his intended words. Over 4,800 hours of use, he has communicated more than 237,000 sentences at roughly 56 words per minute. He works full-time.

    That’s not a laboratory demonstration. That’s not a press release. That’s a BrainGate2 clinical trial participant living his life with a brain-computer interface, reported at Neuroscience 2025 and representing the most sustained, independent, real-world use of a speech and movement BCI ever documented. And it’s one data point in a field that, after two decades of incremental academic progress, is now moving fast enough that the clinical evidence is outpacing most people’s mental model of what’s possible.

    So: can BCIs restore movement after paralysis? The honest answer requires separating three very different things that get conflated in headlines—restored communication (controlling a cursor or generating speech), restored functional movement (moving a paralyzed limb), and restored independent mobility (walking). The evidence is strongest for the first, genuinely promising for the second, and early but real for the third.

    Communication: the problem that’s closest to solved

    The clearest clinical wins in BCI right now are in restoring communication for people who’ve lost the ability to speak or type. This is where BrainGate has the deepest data.

    A March 2026 study published in Nature Neuroscience demonstrated that two BrainGate participants—one with ALS, one with a cervical spinal cord injury—could type on a standard QWERTY keyboard layout by attempting finger movements. Not imagined cursor movements. Not an abstract mental task. Actual attempted typing—the participants thought about pressing specific keys with specific fingers, the implanted microelectrode arrays recorded the neural patterns associated with each attempted movement, and a decoder translated those patterns into keystrokes in real time. The system achieved speeds approaching 90 characters per minute, which is in the range of normal phone typing for a non-disabled person.

    A separate BrainGate participant at UC Davis achieved 97 percent accuracy on a speech BCI that translates attempted speech into text—the most accurate speech neuroprosthesis ever reported, published in the New England Journal of Medicine. The system reconstructed the patient’s voice from pre-disease recordings, so the synthesized output sounds like him, not like a generic computer voice. That distinction matters more than the engineering might suggest—hearing your own voice come back to you after disease has taken it is not a technical specification, it’s a human experience.

    Neuralink’s participants have demonstrated cursor control, web browsing, and social media use through the N1 implant, with 21 patients now enrolled globally. Synchron’s endovascular BCI—threaded through the jugular vein, no craniotomy required—has enabled an ALS patient to control an iPad, an Apple Vision Pro, and Amazon Alexa using thought alone, all through native accessibility protocols on consumer devices. These are real outcomes in real patients. The communication problem for severe paralysis is not solved, but the clinical evidence now clearly demonstrates that implanted BCIs can restore functional digital communication at speeds that make them practical for daily life.

    Functional movement: the harder problem

    Restoring communication means decoding neural signals and routing them to a computer. Restoring movement means decoding neural signals and routing them back into the body—either to a robotic limb, a functional electrical stimulation system, or a spinal cord stimulator that reactivates the patient’s own muscles below the injury. The decoding part is the same. The output part is enormously more complex.

    BrainGate participants have controlled robotic arms using neural signals since the early 2010s—the 2012 demonstration where a woman with tetraplegia used a BCI-controlled robotic arm to drink coffee from a bottle was a watershed moment in the field. Nathan Copeland, implanted in 2015, used a BCI-controlled robotic arm to fist-bump President Obama in 2016 and later demonstrated bidirectional BCI capability—not just controlling the arm with his brain, but receiving tactile sensation feedback through intracortical microstimulation of his somatosensory cortex. He could feel when the robotic hand touched an object. That sensory feedback loop—reaching, grasping, and feeling what you’ve grasped—is where BCIs start to approximate actual limb function rather than just cursor control applied to a mechanical arm.

    A landmark Neuroscience 2025 report provided the most extensive human safety data ever published on intracortical microstimulation for artificial touch. Five participants received millions of electrical stimulation pulses to their somatosensory cortex over a combined 24 participant-years. The stimulation evoked stable, high-quality tactile sensations in the hand without serious adverse effects. More than half the electrodes continued functioning reliably even after a decade of implantation in one participant. That’s the kind of long-duration safety data the field has needed—demonstrating that you can stimulate the brain to create artificial sensation chronically, over years, without breaking things.

    The most dramatic functional movement results, however, are coming not from BCIs alone but from the combination of BCIs with spinal cord stimulation—and this is where the story gets genuinely exciting.

    Spinal cord stimulation: the other half of the equation

    ONWARD Medical’s ARC-EX system received FDA clearance in December 2024—the first non-invasive spinal cord stimulation device cleared for spinal cord injury. The system places electrodes on the skin at the back of the neck and delivers programmed electrical stimulation to the cervical spinal cord. In the pivotal Up-LIFT trial, published in Nature Medicine, 90 percent of participants with chronic incomplete tetraplegia showed improved upper-limb strength or function. Eighty-seven percent reported improved quality of life. Four participants demonstrated changes in their neurological level of injury, and three improved their AIS (American Spinal Injury Association Impairment Scale) classification—including one participant who moved from complete to incomplete spinal cord injury. That last detail is worth pausing on: a person classified as having a complete injury—no motor or sensory function below the level of the lesion—regained measurable function.

    ONWARD’s implantable system, ARC-IM, goes further. Epidural leads are placed directly on the spinal cord and deliver targeted stimulation that can restore stepping movements in people with complete paraplegia. The research, led by Grégoire Courtine and Jocelyne Bloch at EPFL and Lausanne University Hospital, has produced videos that are almost surreal to watch—people who have been told they will never walk again, standing up and taking steps with epidural stimulation active. A 2025 paper in Science Translational Medicine demonstrated that high-frequency epidural stimulation reduced spasticity and facilitated walking recovery in patients with spinal cord injury, establishing another mechanism by which electrical stimulation of the spinal cord can restore function that was thought to be permanently lost.

    The next logical step—and ONWARD is actively developing this—is pairing spinal cord stimulation with a brain-computer interface. The ARC-BCI system would use a cortical implant to decode the patient’s intended movements, then route those decoded intentions to the spinal cord stimulator, which would activate the appropriate muscles in the correct sequence to produce natural-feeling movement. Brain thinks “step forward.” Decoder translates the intention. Stimulator activates the leg muscles. The patient walks. Not with a robotic exoskeleton strapped to the outside of their body, but with their own legs, driven by their own neural intentions, bridged across the injury by electronics.

    This hasn’t been demonstrated in a full clinical trial yet. It’s in feasibility studies. But every component has been individually validated in humans: the cortical decoder works, the spinal cord stimulator works, and the closed-loop integration is an engineering challenge, not a science challenge. The gap between “each piece works separately” and “the integrated system works reliably in daily life” is real—and it’s the kind of gap that takes years to close—but it’s a gap measured in engineering iterations, not fundamental breakthroughs.

    What “restored movement” actually looks like in practice

    Here’s the part that gets lost in the headlines. When a BCI study reports “restored movement,” the movement being restored is typically not what a healthy person would recognize as normal motor function. A BCI-controlled robotic arm reaches more slowly, grasps less precisely, and fatigues faster (in terms of signal quality, not muscle fatigue) than a biological arm. Spinal-cord-stimulation-assisted walking involves extensive preparation, careful calibration, and a level of concentration from the patient that makes it exhausting rather than automatic. These are real functional gains—the difference between being able to grasp a cup and not being able to grasp a cup is enormous when you’re the person holding the cup—but they’re not the seamless restoration of pre-injury function that the promotional materials sometimes imply.

    The trajectory matters more than the current state. The BrainGate participant typing at 90 characters per minute in 2026 is operating a system that typed at roughly 15 characters per minute a decade ago. The speech BCI achieving 97 percent accuracy in 2025 is operating a system that achieved roughly 70 percent accuracy five years earlier. The decoders are getting better because the AI is getting better, the electrode technology is improving, and the cumulative participant-hours of data are feeding algorithms that learn to interpret neural patterns with increasing precision. The slope of this curve matters as much as the current position on it.

    The honest timeline

    BCIs that restore functional communication for people with severe paralysis will be commercially available medical devices within three to five years—probably led by Synchron’s endovascular approach or a Neuralink-derived product, with BrainGate’s academic work continuing to push the frontier of what’s decodable. BCIs that restore basic upper-limb movement—grasp, reach, manipulation—through robotic arms or functional electrical stimulation are probably five to ten years from routine clinical use. Integrated BCI-plus-spinal-cord-stimulation systems that restore walking for people with paraplegia are further out—likely a decade or more from anything resembling standard clinical practice—but the foundational work is human-validated and advancing.

    None of this is speculation. It’s extrapolation from clinical data that exists, published in Nature, Nature Neuroscience, the New England Journal of Medicine, and Science Translational Medicine. The field has moved past proof of concept and into the phase where the questions are about reliability, scalability, durability, and insurance coverage—which are the boring questions that mean the technology is real.

    We cover the full landscape of brain-computer interfaces and neuroprosthetics—from the earliest experiments to every company and approach described above—across 48 lectures in our Neuroprosthetics & Brain-Computer Interfaces course. If the BrainGate typing data or the spinal cord stimulation results changed what you thought was possible, the course goes considerably deeper.