Above: Image taken from Supplementary Video 2: Implementation of the Brain-Spine Interface, from the paper “Walking naturally after spinal cord injury using a brain–spine interface,” published May 24, 2023 in the Journal Nature.


At least once a year Gregoire Courtine’s spinal cord stimulation lab in Switzerland publishes a research study; well-written, solidly scientific, beautiful multimedia presentations, they always seem to wind up in the top journal Nature. They’re always news desk catnip and the headlines are always the same: “paralyzed man walks.”

This past week Courtine’s group published another paper in Nature, “Walking naturally after spinal cord injury using a brain–spine interface.” I urge you to read the whole thing, and watch the accompanying videos, it’s available, deep with data and open access for all.

Here we go again. The press went full feeding frenzy. If you live with a spinal cord injury, you couldn’t have missed this brain-spine hope-fest. Your friends and family all shared it with you. Your social feeds are saturated with it. Good Morning America’s coverage was 100 percent gee whiz, led by Christopher Reeve’s son Will, saying his dad would’ve been first in line to get something like this. NBC, Washington Post, NYT, BBC, Al Jazeera, they all ran with the story.

A Digital Bridge

Bio-tech wise, it’s brilliant work. Here’s the gist of it: Gert-Jan Oskam, a 40-year-old spinal cord injured Dutchman activates wireless brain sensors to transmit his thoughts to a computer. These “motor intentions” are decoded and transferred to a software algorithm, which times and sequences electrical currents to targeted spinal cord dorsal roots via a 16-electrode paddle array on the lumbar cord. This stimulation activates muscle groups to initiate stepping. 

In the scientists’ words, “preprogrammed spatiotemporal sequences replicate the physiological activation of leg motor pools underlying standing and walking.”

From the paper:

This integrated chain of hardware and software established a wireless digital bridge between the brain and the spinal cord: a brain–spine interface (BSI) that converts cortical activity into the analogue modulation of epidural electrical stimulation programs to tune lower limb muscle activation, and thus regain standing and walking after paralysis due to a spinal cord injury.

Said Courtine, in a press release: “We have created a wireless interface between the brain and the spinal cord using brain-computer interface technology that transforms thought into action. Our idea was to re-establish this communication with a digital bridge, an electronic communication between the brain and the region of the spinal cord that is still intact and can control the leg movement.”

Here’s the part about the digital bridge you may not get from the headlines: Oskam has an incomplete spinal cord injury (C5/6) and could already walk. He had the spinal stim device implanted five years ago; when it is switched on, he can step with a walker. He also recovered partial mobility without stimulation. The new study shows him walking with a walker, not very fast, but more smoothly. But he’s moving with volitional motor intention. He can pause, change his stride length, walk up inclines or stairs.

Oskam got a lot of physical therapy as part of the study, which is credited with helping him control hip flexion without stimulation. Per the paper:

… the participant exhibited improvements in all the conventional clinical assessments … These improvements without stimulation translated into a meaningful increase in quality of life, such as walking independently around the house, transiting in and out of a car or drinking a beverage with friends standing at a bar.

What’s going on in the cord? Says the paper:

it is reasonable to assume that the [stimulation] triggered a reorganization of neuronal pathways that was responsible for the additional neurological recovery. These results suggest that establishing a continuous link between the brain and spinal cord promotes the reorganization of residual neuronal pathways that link these two regions under normal physiological conditions.

You Can’t Have One 

This is wonderful bioengineering, really pushing the brain-machine interface frontier. This is the first time many have heard of the French WIMAGINE technology, the brain signal sensor used here. It’s not implanted, as is the Utah Array. Skull bone is removed and the titanium-cased chip sits atop the brain membranes. 

Coincidentally, the latest Courtine study was released a day ahead of an announcement on Twitter from Neuralink, the Elon Musk brain stim start up. They say they have FDA approval to begin a human trial. For what, for whom, when, no details are available. 

Meanwhile, none of this is available, it’s not going to be available in the foreseeable future. The brain-spine story remains a research project.

Some considerations to keep expectations real:

Is this walking “natural,” as the study title has it? You tell me: Here is a guy who still uses a wheelchair for primary mobility. He has a pair of 2-inch square sensors in his scalp (one became infected and was removed), an implanted e-stim paddle on his cord and a pulse generator in his abdomen. He wears a cartoony headset antenna, has a computer in his backpack, and uses a wheeled walker with handbrakes. Natural with an asterisk.

SCI doctor Keith Tansey, a physician/scientist at the Jackson VA Medical Center, is very impressed with the biomedical engineering from Courtine’s group. He says his greatest frustration is with the media’s interpretation of the study. “This may not be as profound as it’s being presented to us in terms of clinical impact, never mind translatability to others, or relative to the cost and complex nature of the intervention. The study participant is an incompletely paralyzed guy who has had locomotor training and then an implanted spinal cord stimulator for several years and has a capability of walking. Here we have a study that shows improved walking in a guy already walking.

“What I don’t want is overinterpretation,” said Tansey. “I don’t want spinal cord stimulation to become stem cells all over again – too much promise, too much expectation and pretty soon people become disenchanted and move on to the next thing being hyped.”

And what about all the PT? Tansey pointed out that Oskam’s motor scores were high enough ahead of the brain-spine study that intensive training alone might have encouraged his improvement, or could in others with similar motor capacity.

Megan Gill, an assistant professor of physical therapy at the Mayo Clinic, told an NBC News reporter it’s hard to tell how much the technology affected Oskam’s recovery, given that his injury was moderate and he underwent extensive rehabilitation prior to the study. The new system "isn’t taking someone completely paralyzed from lying in bed and not moving to up and walking," Gill said. "This person had some ability to stand. They had some ability to walk even before this technology was implanted."

Here’s the U2FP take on media responsibility, from Executive Director Matthew Rodreick: “We in the SCI advocacy community must hold the media to a higher standard of reporting on paralysis research. Very few stories about this brain-spine advance revealed a very simple but critical piece of information: what could Oskam do before the stim and what changed as a result. Without this, our community, many of whom are desperate for any semblance of hope, are misled, which likely leads to disillusionment. This is not something we can afford as we try to mobilize the SCI community to advocate for cures.”

ONWARD

The publicly traded neuromodulation company Onward is a contributor to the new brain-spine research and certainly took advantage of the publicity bonanza. Oskam’s e-stim array was implanted as part of the company’s 2017 STIMO clinical trial in Switzerland. When the company was founded (in 2011 as NeuroRecovery Technologies) the goal was to manufacture (they now say purpose-build) e-stim paddles optimized for SCI motor function, not pain. Onward has its own paddle now, and has just begun using it in human trials. But to date, all spinal cord stim studies, all the Louisville trials, all the Mayo and University of Minnesota trials, have implanted old school paddles made to treat pain – this includes Oskam’s unit, which is from Medtronic. So is his implanted pulse generator. 

I asked Onward CEO Dave Marver to sort out the company’s role. He has previously stated publicly that the company’s pursuit of epidural stim implant regulatory/marketing approval will not address walking. It will be clinically trialed for blood pressure management. 

Digression: Do you think the Washington Post will cover the story in a few years when Jane Doe gets a stimulator implant to calm her autonomic dysreflexia or help her manage her bladder? Even if she reports major quality of life benefits? Unless she’s shown walking into a bar to order a beer, there’s no story.

Here’s what Marver had to say: 

ONWARD has developed a set of electrical stimulation protocols for our various SCI-focused therapies currently in development. We call these proprietary stimulation protocols ARC Therapy. Medtronic deserves credit for providing academics with devices that have facilitated important SCI research. Indeed, the STIMO mobility study that was conducted in Switzerland and published in Nature included use of modified Medtronic systems. 

ONWARD was an important contributor to the research group behind the BCI innovation, providing financial support, regulatory support, and the SCI-specific stimulation protocol (ARC Therapy) that is responsible for driving the participant’s mobility, now powered by thought.

ONWARD has been working to develop purpose-built hardware systems to deliver ARC Therapy for the benefit of people with SCI. Our systems are designed to deliver the highly flexible and specific stimulation protocols required to restore mobility and other movement-related functions, in addition to addressing autonomic functions such as blood pressure regulation, continence, and sexual function.

We started implanting the ONWARD ARC-IM IPG neurostimulator in clinical studies in May 2022 and the ONWARD ARC-IM Lead in clinical studies this month.

In the coming year the Courtine group and Onward plan to enroll four more participants to test the brain-spinal cord system. Two subjects will be tested for upper extremity volitional movement. We’ll be there to decode the media coverage.