Paralysed man can walk again

A man paralysed from the chest down has been able to walk again thanks to a new brain-muscle interface device developed by scientists in California.

Spinal injuries often lead to permanent disability, including paralysis and loss of sensation in the part of the body below the level of the injury.

This was the case for a 26 year old American man, who has not walked since he sustained damage to his spinal cord at the level of his sixth thoracic vertebra, robbing him of the use of his legs and leaving him without sensation over the lower half of his body.

Now, he has been able to take steps independently again thanks to a first-of-a-kind device developed by University of California, Irvine engineer Zoran Nenadic and his collaborator neurologist An Do.

The device comprises a matrix of electrodes woven into a close-fitting cap. This fits around the head and picks up electrical signals from the brain, which are sent to a computer which has been programmed to register brain activity corresponding to the patient thinking about walking.

When these signature patterns are detected, the computer activates a muscle stimulator to deliver a pattern of electrical impulses to the leg muscles to trigger a pattern of walking movements.

After a number of weeks in training, the patient was able to use the device successfully to stand and take steps autonomously. He described the experience as feeling like walking had before his injury, although without the ability to feel the positions of his legs owing to his loss of sensation.

This is in fact an aspect that Nenadic is working on now to provide the user with feedback so that they do not have to watch their feet constantly just to know where they are putting them.

The duo developed the system in a series of stages. First they trained the subject to think along the right lines by asking him to learn to control a cartoon image on a computer using just his thoughts. This works because certain patterns of thoughts produce specific patterns of brain activity, which the computer can be programmed to detect.

The on-screen avatar was then scaled to a robotic leg on a treadmill, which the patient again learned to control by thinking in the right way. Finally, the computer was coupled to the muscle stimulator, which had the capacity to control the patient's own muscles, allowing him to voluntarily control his own lower limbs for the first time in many years.