A trial will compare three stimulation approaches to restore touch in people with quadriplegia after spinal cord injury.
Quadriplegia, paralysis of all four limbs caused by spinal cord injury, can leave people unable to feel objects they are trying to grasp or the sensation of holding another person’s hand.
A US$3.1m grant from the Eunice Kennedy Shriver National Institute of Child Health and Human Development will support work to develop the best strategies for restoring touch.
Emily Graczyk, assistant professor of biomedical engineering at the Case School of Engineering and Case Western Reserve School of Medicine, said: “When someone loses sensation from a spinal cord injury, they lose not only the ability to feel objects they’re trying to grasp, but also the emotional connection that comes from holding a loved one’s hand.
“Our goal is to find the best way to give that back.”
The grant will fund the first systematic comparison of three different approaches to artificial touch: stimulating the brain directly, stimulating peripheral nerves in the arm or combining both methods.
The new study will integrate sensory feedback into neuroprostheses, prostheses that integrate directly with the nervous system, to restore reaching and grasping with the goal of greater independence and better quality of life.
Researchers will also test whether pairing brain and peripheral nerve stimulation promotes neuroplasticity, or rewiring of the brain, allowing users to recover some sensation on their own below the point at which the spinal cord is severed.
Graczyk said: “Unlike amputation, where the limb is completely gone, people with spinal cord injury often have incomplete sensory loss.
“There is the potential for neuroplasticity, for the nervous system to reorganise and recover function. We want to know if providing artificial sensation through stimulation can help promote that recovery.”
The research builds on work led by Abidemi Bolu Ajiboye, the Robert & Brenda Aiken professor of biomedical engineering, who is exploring brain-computer interfaces to restore function to people with severely debilitating injuries to the nervous system, such as spinal cord injuries and stroke.
The new study will take a systematic approach to optimising sensory feedback for participants with quadriplegia who are already enrolled in the Reconnecting the Hand and Arm to the Brain (ReHAB) clinical trial at Case Western Reserve.
These participants have permanently implanted electrodes in their brains and nerve-cuff electrodes in their arms, allowing researchers to test all three stimulation approaches.
Graczyk said: “Researchers have made remarkable progress in helping people control robotic arms or their own paralysed limbs using brain signals.
“But without sensation, these systems remain difficult to use. It’s like trying to pick up an egg while wearing thick gloves. You can’t tell if you’re squeezing too hard or not hard enough.”
Studies have shown that sensory feedback dramatically improves the functional utility of prosthetic systems.
“But equally important is the emotional and psychological impact of restored touch.
Graczyk said: “We’ve heard from participants that being able to feel again, to hold hands with family members, to pet their dog, to feel the texture of fabric, has profound meaning beyond just functional benefits.
“Touch is how we connect with the world and with each other.”
