Sunday, April 14, 2024

A new way to restore hand mobility thanks to an electrified patch

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The proverbial story to overcome paralysis tends to start with the legs: Superman swear to walk again; a soap opera character comes out of his wheelchair. “I think society tends to focus only on the walking aspect of disability,” says Ian Ruder, editor of United Spinal Association magazine, a nonprofit advocacy group for people with injuries. and spinal cord disorders. But Ruder, who used a wheelchair following an injury 23 years ago, says even restoring a fraction of his hand’s function would improve his quality of life more than walking. “The difference between being able to pinch me with my thumb and not being able to pinch me with my thumb is difficult for most people to understand,” says Ruder. “It would open up a whole new level of independence.”

Ruder isn’t the only one feeling this. Surveys of people people with quadriplegia find that they consider recovery of the hand, bladder, trunk and sexual function a higher priority than walking. Yet, effective and accessible technologies for restoring motor function in a person’s upper limb – rather than via a prosthetic device– were rare. Earlier this month, however, researchers from the departments of rehabilitation medicine and electrical and computer engineering at the University of Washington reported that they had restored some function to the hand in six people using an electric current delivered by patches on the neck. The benefits appeared quickly and lasted for several months after the trial without continuous stimulation, all without invasive surgery.

“It’s totally exciting,” says Ruder, who was not in the study. “The possibility of restoring function with such a non-invasive and simple approach is enormous.”

The lower body, especially the limbs, is gaining more researchers’ attention, in part because arm and hand movements are a more complicated dance of motor neurons, muscles, and joints. Researchers have tried to replace or restore this function with a range of technologies, ranging from brain-computer interfaces (BCI) and prostheses electrical stimulation of nerves and muscles. Implanted BCIs are promising, but they require surgery to position a chip that reads brain activity, translates it into usable commands, and is carried long-term – and there are costs and infection risks associated with that. Fatma Inanici, a rehabilitation and neuroscience researcher at the University of Washington’s Chet Moritz Lab and lead author of the study, is working on something more accessible. “Instead of having surgery,” she says, “you can put the electrodes on the skin and turn on the device to stimulate the spinal cord.”

Work of Inanici, published in IEEE Transactions on Neural Systems and Rehabilitation Engineering, is built on previous evidence that current in the spinal cord improves mobility. His team’s trial tested whether pairing this stimulation with physical rehabilitation training for participants’ hands would allow them to perform activities that they could not achieve with training alone. Six people paralyzed with spinal cord injuries joined the trial, each with a range of different abilities, ranging from almost no hand function to more than 50 percent. For a month, they worked weekly with a personal trainer, pinching beads, stacking blocks and tying knots. But rehab only got them so far. “All of these things have been extremely difficult for me,” says Jessie Owen, a Washington teacher and one of the participants. “I haven’t made much progress.”

The following month, Inanici and his team glued two flexible round hydrogel electrodes to the back of each participant’s neck, just above the neck. Each patch was about as flat and wide as a quarter and wired to a pacemaker the size of an old cell phone.


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