Saturday, April 10, 2010

Paralyzed Limbs Revived By Hacking Nerves

A Neural Engineer from Case Western Reserve University, Matthew Schiefer, has developed a brilliant workaround for spinal cord injuries, and it may someday let paraplegics activate their legs just by pushing a button.  More after the jump.

Schiefer developed this as an experiment in which pulses of electricity are used to control the muscles of an unconscious patient, as if they were a marionette. It represents the beginnings of a new generation of devices that he hopes will allow people with paralysed legs to regain control of their muscles and so be able to stand, or even walk again.

His is one of a raft of gadgets being developed that plug into the network of nerves that normally relay commands from the spinal cord to the muscles, but fall silent when a spinal injury breaks the chain. New ways to connect wires to nerves allow artificial messages to be injected to selectively control muscles just as if the signal had originated in the brain. Limbs that might otherwise never again be controlled by their owners can be brought back to life.

The potential of this approach was demonstrated in 2006 when a different Case Western team enabled someone who was paralysed from the waist down to watch their usually motionless knees straighten at the push of a button. With a little support they even stood for 2 minutes while signals injected into nerves in their thighs kept their knees straight.

But controlling one joint alone is not enough. Schiefer's latest experiment uses a new method to plug into a nerve to control the four muscles needed to stand up from a sitting position.

Motor nerves like this are in some ways like telephone cables: they are made up of electrically isolated bundles of nerve fibres, each one of which connects to certain groups of muscle cells. In the 2006 trial, electrodes were simply placed on the nerve's surface using a spiral cuff, but this makes for a poor connection with fibre bundles close to the nerve's core. The new solution, known as the flat interface nerve electrode (FINE), is a cuff that squashes a nerve flat to bring fibre bundles closer to the surface - and to the eight electrodes in the device's soft rubber lining.

Future devices using FINE would likely be targeted at people paralyzed from the waist down. A computer interface to the implant could give them control of their legs. Further into the future, a brain interface might allow a person to control their implant with their thoughts.

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