Device to help paralyzed walk again developed

By implanting electrodes in the brain and spinal cord to build a "nerve bypass" system between the two body parts, scientists from Fudan University in Shanghai have reached a breakthrough in brain-spine interface research, creating a device that could enable paralyzed people to walk again.

Using the device, people who are paralyzed due to spinal cord injuries could regain control of the muscles in their lower limbs so that they can stand and walk, said the researchers from the Institute of Science and Technology for Brain-Inspired Intelligence of Fudan University.

Jia Fumin, the lead researcher, said that clinical trials are expected to kick off at a domestic tertiary hospital later this year.

The spinal cord functions as a high-speed channel connecting the brain and the peripheral nervous system. If the spinal cord is damaged, instructions from the brain telling muscles to move can't be transmitted, causing paralysis. Since nerve injury is irreversible, current treatments for such patients are limited.

A national report released by a number of institutions, including the China Association of Persons with Physical Disability, last September showed that there were 3.74 million patients with spinal cord injuries in China, and there are about 90,000 new cases in the country each year.

Last year, a research team from the Swiss Federal Institute of Technology in Lausanne carried out brain-spinal interface research on paralyzed patients.

By collecting and decoding brain signals, electrically stimulating relevant areas of the lower limbs, and connecting the brain and spinal cord nerve pathways, they were able to help paralyzed patients with spinal cord injuries regain control of their muscles and walk.

However, challenges remained, including decoding electrical activity in the brain, reconstructing spinal cord nerve roots, and facilitating system integration and clinical application.

"In response to these problems, we devised a new generation of devices that allow the brain-spinal interface to be highly precise, and they come with high throughput and low latency," Jia said.

For example, the device can precisely stimulate the nerve roots of the spinal cord and alternately activate the corresponding muscle groups of the lower limbs so that a patient can walk more naturally.

Moreover, to ensure a smooth walking process, the device makes real-time adjustments of the stimulation parameters acting on the spinal cord according to a patient's posture and movements of their lower limbs.

"Integrating multimodal technologies, such as infrared motion capture, electromyography, inertial sensors and plantar pressure pads, our team constructed a data set of healthy walking postures as well as a variety of abnormal postures, and established an algorithm model, so that we achieved high-performance tracking of continuous walking postures," Jia said.

Compared with the Swiss team's research, which required patients to have three devices implanted in their brain hemispheres for brain signal collection and spinal cord stimulation, Jia's team integrated the devices into one single tiny device implanted in the brain to reduce the number of postoperative wounds.

Such a solution can also shift the decoding process from outside the body to within the body, which can improve the stability and efficiency of brain signal collection and achieve a decoding speed of brain signals and stimulation instruction output that are similar to that of a normal ambulatory person, the researchers said.

"This means that in the future, the walking postures of patients with spinal cord injuries will be more natural and smooth," Jia said.