Paralyzed Man Keeps Hand Function Three Months After Brain-Stimulation Device Turned Off

Keith Thomas retained the ability to move his hands and feel pressure after researchers turned off brain stimulation for three months. Thomas, 48, has been paralyzed from the chest down since a July 2020 diving accident and previously had no sensation or voluntary limb control.

Surgeons at the Feinstein Institutes for Medical Research implanted five electrodes in brain regions linked to arm movement and sensation in 2023.

Computer cables connected the electrodes to an AI system that decoded Thomas’s intended movements and sent signals to electronic splints on his arms, hands and fingers. Force sensors in 3D-printed wearables on his hands delivered pressure feedback through electrical stimulation to sensory areas of his brain.

The research team had planned to stop stimulation for one month to check for lingering effects.

A fire in the building extended the period without stimulation to about three months. After that interval Thomas retained strength, feeling and hand function, with improved individual finger control. He raised his elbows nearly to shoulder level and reported a tingling sensation in his wrist when pressure was applied, even when disconnected from the computer system.

Thomas also participated in experiments in which he felt objects through another person’s hand via the implant. Chad Bouton, a researcher at the Feinstein Institutes, said the team observed stronger neural responses in Thomas’s sensory cortex after the intervention. “We turned everything off completely, for many months, and yet he’s maintained these gains,” Bouton said.