New Bionic Spinal Cord Might Help the Paralyzed Walk

A new match-sized invention is expected to return independent mobility to paralyzed patients as early as next year.

Australian researchers have developed a stent-based electrode (stentrode) that can be safely implanted into the brain and will allow users to control mobility mechanisms (like robotic limbs, exoskeletons or wheelchairs) through brain commands alone.

“Currently, exoskeletons are controlled by manual manipulation of a joystick,” explains Dr Nicholas Opie, a co-principal investigator of the device and biomedical engineer at the University of Melbourne. Manual control means that until now, there hasn’t been much out there for patients suffering complete paralysis. “The stentrode will be the first device that enables direct thought control of these devices,” says Dr Opie.

It’s some real science-fiction stuff and Dr Opie and the rest of the research team are understandably excited. Principal author and neurologist at the Royal Melbourne Hospital and research fellow at the Florey Institute of Neurosciences and the University of Melbourne, Dr Thomas Oxley, called the stentrode revolutionary and explained how it works.

Image: The University of Melbourne

The 2 cm long, 3 mm wide mesh stenrode is implanted into a blood vessel and interacts on an electrical level with surrounding tissue (in that way, the device is conceptually similar to an implantable cardiac pacemaker, according to Dr Opie). The device is placed next to the motor cortex of the brain where it picks up high-quality brain signals associated with movement. Those signals are then translated through a computer and fed back as commands to a mobility assist mechanism.

“In essence, this a bionic spinal cord,” Dr Oxley says.

Not only is the device a breakthrough in what it could offer to paralyzed patients, but it also signals a new era in minimally invasive brain surgery.

One of the problems with technology that tries to interact with brain signals is that surgeons have to delve pretty deep into the grey stuff – usually through open brain surgery – to pick up those signals. But the research team says their device can be dropped off in the brain through a relatively low-risk angiograph.

The device is made of nitinol, a resilient nickel titanium composite. And its structural design means it can be compressed into a 1mm diameter catheter and guided through the brain then dropped off near the motor cortex. Once deployed, the nitinol stent expands to size and the catheter is guided back out. After the implant, the patient is left with minimal brain trauma and a pretty superficial cut.

Image: The University of Melbourne


Image: The University of Melbourne

The stentrode is also surprisingly biocompatible; the team’s studies showed that not only is the stent safe for long term use, but its ability to pick up brain signals actually improved over time, as the body accepted it.

So far the team has recorded brain signals of freely moving sheep, but the first in-human trials will start next year at the Royal Melbourne Hospital. If all goes to plan, Dr Oxley says the applications for their device don’t stop at paralysis; the relatively easy delivery process and high quality of interaction with the brain means the stentrode could help treat a range of neurological conditions.

“Multiple deep brain stimulation targets (are) accessible via arteries and veins,” according to Dr Oxley. “Targets for Parkinson’s disease and obsessive-compulsive disorder (are) particularly suitable.”

Dr Opie suggests the device will also be suitable to detect and stop epileptic seizures.

“Almost all neurological conditions may be able to be treated with this technology,” he says. “Whether it is epilepsy, Parkinson’s, depression, Alzheimer’s, you know, the list goes on.”

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