Itch Relief by Mirror Scratching
For this
assignment, I decided to choose the winning study for the 2016 IG Nobel Prize
for Medicine.
For those of you
who do not know what they are, the IG Nobel Prizes are parodies of the Nobel
Prizes, that are held every year in Oslo, Norway. Every autumn are given 10
prizes to unusual or trivial achievements in scientific research. This idea was
first organized by the humour magazine Annals
of Improbable Research, in 1991, with the aim to “honour achievements that
first make people laugh, and then make them think”, they wanted to celebrate
the unusual, honour the imaginative and stimulate the interest of everyone for
science, medicine and technology.
The name IG Nobles, is a play on the words ignoble and Nobel Prize, the
pronunciation used during the ceremony is IG-noh-BEL.
Some of this
past year’s winners include "Effect of Different Types of Textiles on Sexual
Activity. Experimental study,"
by Ahmed Shafik, winner of the Reproduction Prize, and "The Brand Personality of Rocks: A Critical Evaluation
of a Brand Personality Scale,"
by Mark Avis, Sarah Forbes, and Shelagh Ferguson, winner of the Economics
Prize. If you would like to check them out, I’ll leave you the following link http://www.improbable.com/ig/ .
I wanted to
choose something different from what my colleagues have chosen, I wanted to
play around a little bit with this assignment, and maybe make my colleagues
laugh a little bit while they think on the possible repercussions of the study
I’m going to present.
The study is
entitled “Itch Relief by Mirror
Scratching. A Psychophysical Study.” By Christoph Helmchen, Carina
Palzer, Thomas F. Münte, Silke Anders and Andreas Sprenger, from the Department
of Neurology of the University of Luebeck in Germany.
What is itch?
We have all felt it, that annoying sensation of itching, that can make you go
crazy if do not scratch yourself. Helmchen and his team define Itch as the unpleasant
sensation that provokes the desire to scratch the itching site. They also say
that histamine reliably elicits itch, it is released by mast cells and
activates unmyelinated peripheral C-fibers and spinothalamic lamina I neurons,
that transmit this signals to the brain regions that encode location and
intensity of somatosensory sensations.
Under normal
circumstances, scratching immediately attenuates the itch. But what if the
patient has an inflammatory skin disease, such as atopic eczema, that elicits
an itch sensation, but when you scratch the skin rashes and skin inflammation
may deteriorate and get worse. Even though there are drugs that can sooth the
itching, this itch relief is not always achieved.
The objective of
this study, is to test whether the central mechanism that induce the
attenuation of the itch by scratching can be activated by scratching the
contralateral limb to the itching limb, when you present the patients with
mirror images of the non-itching limb as the itching limb.
This idea of
tricking the brain using mirrors, has been proposed recently, on patients that
had an itch on a phantom limb, and that it was relieved by watching the
reflection of scratching on the corresponding intact limb in a mirror, or when
amputees or stroke patients, observe their intact limb in a mirror box, which
can lead to illusionary perception that their phantom hand, has been
resurrected and that it is moving. This technic was also applied to relieve
pain in CRPS type 1 (Complex Regional Pain Syndrome).
Observing a
mirror image of one’s own limb can lead to the illusionary perception that the
mirrored limb is one’s own contralateral limb. This proves that visual clues
dominate, when we have a conflict between our visual and our tactile
perceptions, this way we can “fool” the brain into perceiving stimulus that do
not actually exist.
I won’t explain
the full range of details of the study, since it is a very comprehensive study
and I would need a lot more than 1000 words to do so, but I’ll present you the
basic experimental study that it was used. If you would like to know more about
it I’ll leave you at the end, the link of the publish study paper.
Healthy
participants were asked by Helmchen and his team, to assess the intensity of an
experimentally induced itch, with dihydrochloride histamine injected into the
dermal-epidermal junction on their right forearm while they observed someone
scratching their arms, either their right (itching) or their left forearm
(non-itching), which were either mirrored or not mirrored. In the first
experiment, a mirror was placed between the participant’s forearms and was used
to create a visual illusion that someone was scratching his right forearm,
while it was the non-itching arm to be scratched.
A second
experiment was executed, to control the visibility of the left forearm
(non-mirrored), where it was used flipped and unflipped, real-time video
displays where the participants were showed either scratching on one forearm,
or both, or none at all.
In both
experiments, scratching the non-itching forearm attenuated the itch, and
selectively in the mirror condition, for example, when the non-itching forearm
was visually perceived as the itching one.
This way “Mirror
Scratching” might provide an alternative treatment to reduce the perception of
itching in focal skin diseases with persistent and intense pruritus, without
causing additional harm to the affected skin and might therefore have
significant clinical impact.
I would like to
have some of your input about this research topic. Have you ever heard about
the IG Nobel before? Can you think of some other medical contexts where this
method can be applied? What is your opinion in other ways to deceive the brain,
such as the Placebo effect? Have you been scratching as much as I did while I
was writing this entry?
And I would like
to propose to you one last thing, if you can, try to repeat this experiment in
your own home using a mirror, do not read other comments beforehand, I would
like to know your experience, and I would I like you to share it.
You can consult
and download the original publication at:
Mariana Poeiras R. S. Teles
Monday, 8th May 2017
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