Nerve transfer surgery for people suffering tetraplegia after a traumatic spinal cord injury can improve independence, according to new research.

Mary Galea AM, a professorial fellow at the University of Melbourne and Royal Melbourne Hospital, and Natasha van Zyl, a plastic and reconstructive surgeon at Austin Health, explain their research here:

Spinal cord injury is a devastating, life-changing injury.

Every year between 250,000 and 500,000 people worldwide suffer a spinal cord injury, with just over 50 percent resulting in tetraplegia that results in some degree of paralysis in all four limbs—the legs and arms.

Loss of upper limb function affects almost every aspect of a person’s work, family, and social life. Regaining some form of arm and hand function is the highest priority for people with tetraplegia.

Traditionally, some arm and hand functions have been reconstructed using tendon transfers, which move the tendon of a functioning muscle, like one of the elbow flexors, to a new site to recreate the function of a paralyzed wrist extensor.

But nerve transfers allow for direct surgical reanimation of the muscle that is anatomically and biomechanically designed to perform that function.

How does it work?

The process involves taking working nerves to expendable muscles, like one of the muscles that rotates the forearm, which hasn’t been affected by the spinal injury and attaching them to the nerves of paralyzed muscles below the injury; this can restore voluntary control and reanimate more than one paralyzed muscle.

For example, to restore grasp and pinch, the nerve to a spare functioning wrist muscle can be transferred to the nerve controlling thumb and finger flexion.

Our research group, which brought together the medicine department at the Royal Melbourne Hospital, and the plastic and reconstructive surgery department and the Victorian Spinal Cord Service at Austin Health, just published the largest to date prospective, consecutive case series of nerve transfers undertaken at a single center in the tetraplegic population in the medical journal The Lancet.

A case series is a group or series of case reports involving consecutive patients who were given similar treatment.

The sixteen patients—13 male and three female—with average age of 27 years and within 18 months of traumatic spinal cord injury affecting the mid-cervical region (or the neck), were recruited from people referred to Austin Health for assessment in the Upper Limb Clinic.

Most of the injuries were the result of motor vehicle accidents or sports injuries.

Participants underwent single or multiple nerve transfers in one or both upper limbs to restore elbow extension, grasp, pinch, and hand opening.

In ten participants, nerve transfers were performed in one hand to restore grasp and pinch while tendon transfers were performed on the other.

We then looked at the clinical and functional outcomes of 59 nerve transfer procedures in 27 limbs.

Daily activity boost for people with tetraplegia

The people involved completed assessments of their level of independence related to activities of daily living—like self-care, going to the toilet, their upper limb function, muscle power, grasp and pinch strength, as well as hand opening ability—before surgery, one year after surgery, and again two years later.

At the two-year point, we found significant improvements in their independence, and ability to pick up and release objects of different sizes within a specified time.

Prior to surgery, none of the participants were able to perform the grasp or pinch strength tests, but two years later, their pinch and grasp strength was sufficient to allow them to do most activities of daily living.

The outcomes in hands where grasp and pinch had been reconstructed with nerve transfers were similar to those reconstructed with tendon transfers.

But a hand reconstructed with a nerve transfer for grasp and pinch had a more natural appearance and feel for social interactions and opened more easily for use of electronic devices. It meant the patients were satisfied, would have the surgery again and would recommend it to others.

There were four failed nerve transfers in three participants, who later underwent tendon transfer to improve hand function.

There were minor adverse side effects including a change in sensation and a temporary reduction in wrist strength which had resolved by the 12-month assessment. But, there were no serious adverse reactions related to the surgery.

Long-term follow up of nerve transfer surgery is highly desirable and funding to establish a registry is being sought to examine the effects of nerve transfer surgery over time.

Nerve transfer surgery is a safe and effective addition to the surgical techniques available for upper limb reanimation for people with tetraplegia and should be offered to eligible patients.

It can mean a significant improvement in independence after a traumatic and life-changing injury.

Source: University of Melbourne

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A brain-computer interface (BCI) allows people with paralysis to directly operate an off-the-shelf tablet device just by thinking about making cursor movements and clicks, according to results of a small clinical trial.

Tablets and other mobile computing devices are part of everyday life, but using them can be difficult for people with paralysis.

In a study in PLOS ONE, three clinical trial participants with tetraplegia, each of whom was using the investigational BrainGate BCI that records neural activity directly from a small sensor placed in the motor cortex, were able to navigate through commonly used tablet programs, including email, chat, music-streaming, and video-sharing apps.

The participants messaged with family, friends, members of the research team, and their fellow participants. They surfed the web, checked the weather, and shopped online. One participant, a musician, played a snippet of Beethoven’s “Ode to Joy” on a digital piano interface.

Thought control

“For years, the BrainGate collaboration has been working to develop the neuroscience and neuroengineering know-how to enable people who have lost motor abilities to control external devices just by thinking about the movement of their own arm or hand,” says senior author Jaimie Henderson, a neurosurgeon at Stanford University.

“In this study, we’ve harnessed that know-how to restore people’s ability to control the exact same everyday technologies they were using before the onset of their illnesses. It was wonderful to see the participants express themselves or just find a song they want to hear,” he says.

The investigational BrainGate BCI includes a baby aspirin-sized implant that detects the signals associated with intended movements produced in the brain’s motor cortex. Those signals are then decoded and routed to external devices. BrainGate researchers and other groups using similar technologies have shown that the device can enable people to move robotic arms or to regain control of their own limbs, despite having lost motor abilities from illness or injury.

Two of the participants in this latest study had weakness or loss of movement of their arms and legs due to amyotrophic lateral sclerosis (ALS), a progressive disease affecting the nerves in the brain and spine that control movement. The third participant was paralyzed due to a spinal cord injury. All were in a clinical trial aimed at assessing the safety and feasibility of the investigational BrainGate system.

For this study, neural signals from the BrainGate BCI went to a Bluetooth interface researchers configured to work like a wireless mouse. The virtual mouse pairs with an unmodified Google Nexus 9 tablet. Researchers asked the participants to perform a set of tasks they designed to see how well participants could navigate within a variety of commonly used apps, and move from app to app.

The participants browsed through music selections on a streaming service, searched for videos on YouTube, scrolled through a news aggregator, and composed emails and chats.

Functional and fun

The study showed that participants were able to make up to 22 point-and-click selections per minute while using a variety of apps. In text apps, the participants were able to type up to 30 effective characters per minute using standard email and text interfaces.

The participants reported finding the interface intuitive and fun to use, the study notes. One said, “It felt more natural than the times I remember using a mouse.” Another reported having “more control over this than what I normally use.”

The researchers were pleased to see how quickly the participants used the tablet interface to explore their hobbies and interests.

“It was great to see our participants make their way through the tasks we asked them to perform, but the most gratifying and fun part of the study was when they just did what they wanted to do—using the apps that they liked for shopping, watching videos, or just chatting with friends,” says lead author Paul Nuyujukian, a bioengineer.

“One of the participants told us at the beginning of the trial that one of the things she really wanted to do was play music again. So to see her play on a digital keyboard was fantastic,” Nuyujukian says.

Plug and play

The fact that researchers didn’t alter the tablet devices and all tablets had preloaded accessibility software turned off was an important part of the study, the researchers say.

“The assistive technologies that are available today, while they’re important and useful, are all inherently limited in terms of either the speed of use they enable, or the flexibility of the interface,” says senior author Krishna Shenoy, an electrical engineer and neuroscientist.

“That’s largely because of the limited input signals that are available. With the richness of the input from the BCI, we were able to just buy two tablets on Amazon, turn on Bluetooth, and the participants could use them with our investigational BrainGate system right out of the box,” Shenoy says.

The researchers say that the study also has the potential to open important new lines of communication between patients with severe neurological deficits and their health care providers.

“This has great potential for restoring reliable, rapid, and rich communication for somebody with locked-in syndrome who is unable to speak,” says Jose Albites Sanabria, who performed this research as a graduate student in biomedical engineering at Brown University.

“That not only could provide increased interaction with their family and friends, but can provide a conduit for more thoroughly describing ongoing health issues with caregivers.”

Staying connected

As a neuroscientist and practicing critical care neurologist, senior author Leigh Hochberg of Brown, Massachusetts General Hospital, and the Providence VA Medical Center sees tremendous potential for the restorative capabilities of BCIs exemplified in this study.

“When I see somebody in the neuro-intensive care unit who has had an acute stroke and has lost the ability to move or communicate, I’d like to be able to say, ‘I’m very sorry this has happened, but we can restore your ability to use the technologies you were using before this happened, and you’ll be able to use them again tomorrow,'” Hochberg says.

“And we are getting closer to being able to tell someone who has been diagnosed with ALS, ‘even while we continue to seek out a cure, you will never lose the ability to communicate.’ This work is a step toward those goals,” Hochberg says

The device is limited by federal law to investigational use. Additional researchers are from Brown’s Carney Institute for Brain Science, the Providence Veterans Affairs Medical Center, Massachusetts General Hospital, and Stanford.

The Stanford Medical Scientist Training Program; Stanford Office of Postdoctoral Affairs; Craig H. Neilsen Foundation; Stanford Neurosciences Institute; Stanford BioX-NeuroVentures, Stanford Institute for Neuro-Innovation and Translational Neuroscience; Pamela and Larry Garlick; Samuel and Betsy Reeves; the Christopher and Dana Reeve Foundation; the Howard Hughes Medical Institute; the National Institutes of Health’s National Institute of Neurological Disorders and Stroke and National Institute on Deafness and Other Communication Disorders; the Office of Research and Development, Rehabilitation, Research and Development Service of the Department of Veterans Affairs; MGH-Deane Institute; Massachusetts General Hospital Executive Committee on Research; and the Joseph Martin Prize for Basic Research provided funding for the research.

Source: Brown University

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