Prosthetic Limbs May Soon Give Patients the Sense of Touch

It may not be long before patients with prosthetic limbs are given back some of their sense of touch. It has even been said that amputees with prosthetic hands my soon be able to feel the warmth from a cup of coffee. Scientists report that this goal, which would be monumental to those with prosthetic limbs, may be reached in the not-too-distant future.

Scientists at the Rehabilitation Institute of Chicago have been working with a technique that as been around for several years to bring about this triumph. It is the same technique that was used to give patients control of their prosthetic limbs.

The process is called reinnervation. In this process, nerves that went to an amputated limb are rerouted to muscles in the chest.

The first time this process was used was in 2004. Since then, it has been used on several more patients with prosthetic limbs. The procedure has been monitored by physician Todd A. Kuiken and his colleagues in Chicago.

Here's how it works: An electrode is placed on the patent's skin. This electrode picks up the signals from the rerouted nerves and sends those signals to the artificial arm. This allows the am to move with the patients thoughts of its movement.

"When the patient thinks 'Close my hand,' the [rewired] muscle acts as a biological amplifier of the nerve signal," Kuiken says.

Recently, Kuiken and his colleagues added a new component to their research. In their most recent procedure, their first with a female patient, the scientists rerouted sensory nerves as well as motor nerves from the prosthetic limb. During the reinnervation surgery, the sensory nerves were rerouted over muscles in the chest.

Researchers recently reported that the woman that had the surgery performed says using her prosthetic arm now feels natural.

Scientists also tested the woman's skin where it was reattached to sensory nerves. The patient said that she felt tingling sensations that corresponded with specific fingers and parts of her hand when they were pressed. She could also feel sensations of vibration and temperature in her prosthetic limb.

Dawn M. Taylor, a biomedical engineer at Case Western University in Cleveland, says that targeted innervation is a "very novel approach." She hopes that we will soon have the means to increase the sensory impulses even more.

Kuiken and his colleagues are well on their way to doing just that. They plan to work with other research teams to improve the sense of touch in prosthetic limbs. With hard work, their patients may be warming their hands with a cup of coffee sooner than we'd ever imagined.

Source:

Transferred Touch: Sensory Rewiring to Improve Prosthetics(http://www.sciencenews.org/articles/20070210/fob5.asp)