Nerve bypass helps paralysed man move again

Restoration of various finger, hand and wrist movement in a person with paralysis has been achieved for the first time by using signals recorded from the patient's motor cortex, reports a study published in Nature this week.

Paralysis, which involves disruption of signal pathways between the brain and the muscles, affects millions of people worldwide. Systems that translate neural activity into control signals for assistive devices such as robotic arms have previously been developed for human patients, and have also been applied to drive activation of paralysed muscles in non-human primates. However, no such approach had been shown to work in real-time to restore movement in humans until now.

Chad Bouton, Nick Annetta, Ali Rezai and colleagues implanted a microelectrode array in the motor cortex of a 24-year-old male participant with quadriplegia (paralysis of the arms and legs) due to injury of the upper spinal cord. They used machine-learning algorithms to decode neuronal activity and control the activation of forearm muscles through a neuromuscular electrical stimulation system. The participant attended up to three sessions weekly for 15 months after implantation to use this electronic ‘neural bypass’ system. The system enabled the participant to make isolated finger movements and six different wrist and hand motions, allowing him to grasp, manipulate and release objects. Furthermore, he was able to use the system to complete functional tasks relevant to daily living, such as grasping a bottle, pouring its contents into a jar and using a stick to stir the contents of the jar.

Although further improvements in the microelectrode technology, the electrical stimulator system and the algorithms they rely on are needed to allow these results to be more widely applicable, the authors propose that this work will advance neuroprosthetic technology for people living with the effects of paralysis