Tiny spine implant could help paralysed patients to walk

Researchers have revealed a tiny medical device that, when implanted, may allow paralysed patients to walk again. Doctors will insert the device, referred to colloquially as the "bionic spine", into three patients in Australia next year. The device translates commands from the users' brains into commands, which are then routed to bionic limbs via a bluetooth connection. The "bionic spine" has been successfully implanted into sheep, and offers several advantages over the current state of the art in mind-controlled exoskeletons, which frequently require a cranial implant - an invasive surgery. Funding for the trial is being partially provided by the US Department of Defence in a push to rehabilitate wounded soldiers. 

Australian scientists hope that a tiny device just 3cm long and a few millimetres wide will enable paralysed patients to walk again by allowing them to control bionic limbs with the power of subconscious thought.

The new device, dubbed the “bionic spine”, is the size of a small paperclip and will be implanted in three patients at the Royal Melbourne hospital in Victoria next year. The participants will be selected from the Austin Health spinal cord unit, and will be the first humans to trial the device, which so far has only been tested in sheep.

Doctors will make a tiny cut in the neck of the patients and feed a catheter containing the bionic spine up through the blood vessels leading into the brain, until it rests on top of the motor cortex, the part of the brain where nerve impulses that initiate voluntary muscle movements come from. The catheter will then be removed, leaving the bionic spine behind.

The outside of the bionic spine is fitted with electrodes which will detect signals from the motor cortex and send them to a small device that will be implanted in the patient’s shoulder. This device will translate the signals into commands, which will be fed to the bionic limbs via bluetooth to tell them to move.

The procedure and device were developed by researchers from the Royal Melbourne hospital, the University of Melbourne and the Florey Institute of Neuroscience and Mental Health, and are detailed in a paper published in the journal Nature Biotechnology.

Co-principal investigator and biomedical engineer at the University of Melbourne, Dr Nicholas Opie, described it as a straightforward procedure that would only take a couple of hours.

“This is a procedure that Royal Melbourne staff do commonly to remove blood clots,” Opie said.

“The difference with our device is we have to put it in, and leave it in.”

Biomedical engineer at the University of Melbourne, Dr Nicholas Opie, worked with researchers to develop the ‘bionic spine’. Photograph: University of Melbourne - Pursuit.

Prof Terry O’Brien, the head of medicine in the hospital’s neurology department said the development of the bionic spine was the “holy grail” for bionics researchers.

He said while patients would initially have to be taught to think above moving their bionic limbs, over time these thoughts should become subconscious as signals from the brain were more readily converted into movements. The bionic spine would not repair damaged pathways in the brain, he said. Rather, it would help the brain find new ways of doing things.

“For example if I want to pick up a phone, but my hand is paralysed, I can use my other hand to pick up the phone instead,” he said.

“You have a normal way to use the brain to pick up the phone, but if that doesn’t work, you find another way. Your brain learns another function can be harnessed to do what you’ve lost.

“What the stent is doing is putting a recorder over the signals in the brain and providing then a conduit to move the limb via those signals bypassing the damaged area.”

There have been previous devices trialled to allow paraplegics to control the movement of their exoskeleton limbs using only thought; however, most require invasive surgery involving removing a piece of the skull, known as a craniotomy, and which carries a risk of infection and other complications.

In 2014, a 29-year-old paraplegic man, Juliano Pinto, made the first kick of the World Cup using a mind-controlled robotic suit, which included a cap fitted with electrodes. And another existing procedure, which involves puncturing thousands of electrodes into the brain, is only effective for up to a year before the brain starts treating it as a foreign object and grows scar tissue over it.

However, the bionic spine is minimally invasive and less cumbersome than previously developed devices, like the cap and robotic suit.

Opie said the trial of the device would take place in patients with lower-limb paralysis first, because they were among those with the most to gain from the technology.

“Before the device is implemented, we will get patients to do tasks where you can see areas light up in their brain, we might train them to move computer cursor so we’ll get a couple of different regions that become active.”

The device would be planted in the same place as this area of brain activity, he said, and if successful, could be refined to help patients with conditions like epilepsy, obsessive compulsive disorder and Parkinson’s disease.

The research was funded by Australia’s National Health and Medical Research Council and the US Defense Department, which has an interest in rehabilitating wounded soldiers.