After the impressive
presentation given by Dr. Kuiken, it was clear that as advanced as TMR surgery
and its use with bionic implants still has a few kinks. In the rounds of
questions the discussion of proprioception along with the ability to feel
surfaces with the new apparatus had more questions than answers.
Beginning
with the topic of proprioception, Dr. Kuiken made it clear that not much is
known about its neurobiological foundations besides the fact that it requires a
multitude of neural circuits working together in order for humans to truly
possess this body sense. In terms of those suffering from amputations and
utilizing these bionics or prosthetics, it was also mentioned that the “phantom
pain” that these individuals felt was still present regardless of experience
with the apparatuses. Phantom pain referring to the amputee still “feeling”
pain in the limb that was lost through the nerve endings that still exist at
the location of the amputations which proliferate into bundles at said site.
Not only this, but Dr. Kuiken expressed that the phenomena of proprioception is
also afflicted in patients with bionics/prosthetics in his research through the
fact that these patients cannot truly feel where their arm or leg is in the
environment. For example, when one closes their eyes, one knows where their arm
or leg is; but in an amputee with a prosthetic, they have to continuously look
towards their artificial limb because they have no feeling of it moving.
In an
interesting paper published by Hugh Herr from MIT, efforts have produced a
possible method of counteracting these afflictions with phantom pain and
proprioception in amputees with artificial limbs. In this set of experiments,
Herr and his colleagues took muscle endings from different parts of the body in
rats and attached them to the ends of severed nerves to complete the circuit,
so to speak. According to the paper, the newly formed granted the body to sense
the stretch and tension of the previously severed nerve endings which,
according to electrical measurements, would allow improved control and
proprioception when using a prosthetic.
This
finding actually lead to a review of amputation techniques that could improve
the use of prosthetics in amputees which has been tested on three patients by
Matthew Carty, a co-author and professor and Harvard Medical School. In this
new form of amputation, Carty would avoid cutting a limb in a straight line and
instead leave portions of muscle to “cap off” the nerves in order to “complete
the circuit” as seen in the rat experiments. It was shown that these patients
had a reduced amount of phantom pain and increased sense of proprioception in
the months following the operation. Additionally, by having prosthetics
interfacing with the muscle endings directly at the end of amputated areas,
patient control over said artificial limbs increased dramatically. The example
of an amputee being able to step down on a gas pedal without having to look at
it was given as a depiction of the triumph.
In
short, Dr. Kuiken’s use of TMR procedures in conjunction with bionics is a
thrilling and interesting research effort that is sure to lead to great
advances in the field. However, this fairly new publication is sure to make
just as great of an advance, particularly since it focuses on nerve endings
directly at the site of amputation. Still, perhaps each method is preferred
with certain types of amputations. For example, TMR was seen to be particularly
efficient in patients with shoulder-level amputations while this new method was
primarily focused on amputees with below the knee amputations. Still, time will
tell where research in bionics will truly lead to.
References
Phantom Pain. (2014, December 03). Retrieved February
08, 2018, from https://www.mayoclinic.org/diseases-conditions/phantom-pain/symptoms-causes/syc-20376272
Weintraub, K. (2017, June 2). New Approach to
Amputation Could Reduce Phantom Pain. Retrieved February 8, 2018, from
https://www.scientificamerican.com/article/new-approach-to-amputation-could-reduce-phantom-pain/
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