Wednesday, May 3, 2017

Natural Robots

Dr. Gregory Dumanian presented his work on targeted muscle reinnervation for enhanced prosthesis function to the Loyola neuroscience community. Dr. Dumanian was focused on studying how to better control the function of prosthetic limbs to create a more effective prosthetic device. Prosthetics of the past were plagued by being very uncomfortable and difficult to use. Usually only consisting of one joint, with most patients describing them as a tool and rarely using them because of impracticality. His findings were based on the premise that residual limbs contain nerves that are still connected to the brain. By surgically repositioning these nerve endings, a prosthetic can be created that is capable of more precise motor control by the brain.

In the case study he presented, a woman was given a new prosthetic device which was capable of greater functionality (the use of more than just one joint) thanks to the targeted muscle reinnervation. This technique uses residual nerves that are a byproduct of amputation but are no longer connected to the limb. Her pectoral nerves, which still receive input from the brain, were reinnervated. Reinnervation consists of severing the already present motor nerve in order to recreate a connection to the sensory nerve junction which is still connected to the brain. This provides electromyogram signals that control the prosthetic. These signals, which originate from the brain, ultimately allow the patient to regain the ability to control hand and arm movements, now through the prosthetic device.
In the article “A Prosthetic Hand That Can Feel” by Diane Tsai and Alexandra Sifferlin, we are introduced to the work of researchers at Case Western University. They have created a clinically applicable prosthetic hand that has sensory capabilities. The patient, Igor Spetic, lost his hand in an accident 5 years before obtaining this advanced prosthetic device. This new device allows Spetic to perform more precise tasks such as opening bags and holding a cup with more confidence. What I found most interesting was how Spetic claimed that, ”what I'm excited about is knowing that I can go back from being one-handed to being a two-handed person”. This shows how important the sensory capabilities of a prosthetic device can be. It allows for the person to become one with the device they are using. Hopefully to the point that a device is just as natural as the original hand. The work performed by the team at Case Western uses pressure sensors in the hand to send signals to those amputated nerves which are still connected to the brain. By doing this, the patient is able to feel the sensation of touch which allows for the device to be less of a tool and more of a part of their body.

This article in Time Health connects to the work of Dr. Dumanian because his work with targeted muscle reinnervation also dealt with restoring the sensory capabilities of the hand in his patient’s prosthetic arm. As a result of the surgery, touching certain areas of her chest led to the perception of someone touching her hand. He was able to specifically reorganize the nerves, that once relayed sensory information to certain portions of the hand, to the patient’s pectoral muscles. As a result to control the prosthetic, juts by thinking about which hand muscles to use. I believe the work of researchers at Case Western and Dr. Dumanian are relevant because both are taking the idea of prosthesis to the next level. While Dr. Dumanian focuses on created a more natural and useful prosthetic device with greater control by the patient. While the highly precise hand of the Case Western study, allows a patient to do the same thing while also get feedback in the form of touch. To have better control and function with the prosthetic device to eventually lead to a more natural and normal life.

I think the work at Case Western is important because it uses sensors in the hand to relay pressure as neural messages to the brain using a similar technique that Dr. Dumaian does: by connecting the prosthetic to the brain through nerve endings that are still viable, but not used because of amputation. Dr. Dumanian’s study is more focused on how the brain can better control the device while the hand from Case Western allows for the brain to get feedback from the device as well. I believe that both aspects are needed to create a more advanced and useful prosthetic device for patients, combining the sensory capabilities of the Case Western device allows for the patient to feel as though the prosthetic is their own natural limb, while Dr. Dumanian allows for much better control of the device. Combined can move us closer to a more natural prosthetic.

Todd A Kuiken, Laura A Miller, Robert D Lipschutz, Blair A Lock, Kathy Stubblefield, Paul D Marasco, Ping Zhou, Gregory A Dumanian, Targeted reinnervation for enhanced prosthetic arm function in a woman with a proximal amputation: a case study, The Lancet, Volume 369, Issue 9559, 3–9 February 2007, Pages 371-380, ISSN 0140-6736,

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