Brown Implant Restores Feeling for Paralyzed Patients

Paralyzed patients might soon walk without constantly watching their feet, thanks to a breakthrough implant developed by Brown University researchers.

The new device does something no other technology has achieved. It restores both movement and the ability to feel, giving patients with severe spinal cord injuries a sense of where their legs are in space.

Dr. Jonathan Calvert led the study while working as a postdoctoral researcher at Brown. He explains that previous treatments could help paralyzed patients walk on treadmills using electrical stimulation below their injury site. But without sensory feedback, they had to stare at their feet with every step.

"If they are walking on a treadmill, they have to look down at their feet and see where they're placing each one of their steps, which is a big limitation to actually using this in the community or at home settings," Calvert said.

The new approach surgically implants tiny electrode arrays next to the spinal cord. Doctors can then stimulate both above and below the injury site, pairing motor control with sensation at the same time.

Three participants tested the technology in the study, published in Nature Biomedical Engineering. The implant proved safe with no additional adverse effects beyond normal surgical risks.

The sensation doesn't work exactly like it did before injury. Since nerve connections to the brain are severed, patients can't feel their actual legs and feet. Instead, they learn to interpret feelings in other parts of their body, like their chest, as signals about leg movement.

This learning process gets help from machine learning. Patients used a control board with knobs and sliders to adjust their stimulation patterns. That data trained neural networks to deliver the perfect amount of electrical stimulation for each person's unique injury.

The Ripple Effect

The personalized approach matters because every spinal cord injury is different. Time since injury, severity, and remaining neural connections vary dramatically from patient to patient.

Dr. Lakshmi Narasimhan Govindarajan, who worked on the study and now researches at MIT, sees this as just the beginning. The proof of concept opens doors for larger trials and refinements that could help thousands of people with paralysis.

Professor Arto Nurmikko from Brown's Engineering and Physics department notes the implants won't perfectly duplicate a healthy spinal cord's complex signaling. But these sophisticated solutions can truly improve quality of life for people living with severe spinal cord injuries.

The technology offers a permanent solution compared to temporary surface stimulation through the skin, which paralyzed patients often struggle to apply independently at home.

Walking freely without watching every step brings paralyzed patients one step closer to true independence.