How one pain suppresses the other

Date:
December 21, 2020
Source:
Ruhr-University Bochum
Summary:
When two painful stimuli act on us at the same time, we perceive one
of them as less painful. This phenomenon is part of the body's own
pain control system. A dysfunction of this inhibition is associated
with chronic pain disorders.



FULL STORY ==========================================================================
The human perception of pain can vary greatly depending on the
situation. So it is possible that the same pain stimulus feels more or
less painful under different conditions. The body's own pain control
system is responsible for this. Researchers investigate this system
with the research method called Conditioned Pain Modulation, or CPM
for short. "This records how strongly a painful stimulus inhibits the experience of another painful stimulus that is presented at the same
time," explains Assistant Professor Dr. Oliver Ho"ffken, neurologist
at Bergmannsheil.


==========================================================================
In the first study, the research team compared an established CPM model
with a recently introduced variation. With Conditioned Pain Modulation,
two pain stimuli always play a role. The first stimulus, also called the
test stimulus, is administered twice: once alone and once in conjunction
with the second stimulus, the conditioning stimulus. The test person
should assess how painful the test stimulus was on its own and how it
felt while the conditioning stimulus was administered.

An objective criterion In the current work, the team led by Oliver
Ho"ffken, Dr. O"zu"m O"zgu"l and Professor Elena Enax-Krumova compared
two different test stimuli: a tried and tested stimulus caused by heat
pain and a new one triggered by electrical stimulation of the skin. In
both cases the conditioning stimulus was generated by cold water. The electrical stimulation of the skin has a decisive advantage over the
previously used heat method: it allows the changes in brain activity
triggered by the electrical stimuli of the skin to be measured with the
help of EEG recording. This adds an objectively measurable criterion to
the subjective pain assessment of the test persons.

Two mechanisms with the same result In the second study, the researchers
used the previously tested CPM model with the electrical stimulation
of the skin and compared it to the pain-relieving effect of cognitive distraction. They found that both the CPM method and cognitive distraction
can reduce the sensation of pain to a similar degree.

However, the two methods showed different results in the measurement of
the electrical potentials. "Based on our measurements, we assume that the
two pain- relieving effects examined are two different neural mechanisms
that just lead to the same effect," says Ho"ffken.

The researchers carried out their studies on healthy volunteers. However, research into the body's own pain inhibition system is also relevant
in order to better understand various pain disorders. "In patients with
chronic pain, the development of postoperative pain and the transition
from acute to chronic pain, changed CPM effects have already been found
in the past. In our research group, we therefore use the CPM model as
an instrument to investigate mechanisms in the processing of painful information," explains Ho"ffken.


========================================================================== Story Source: Materials provided by Ruhr-University_Bochum. Original
written by Judith Merkelt-Jedamzik. Note: Content may be edited for
style and length.


========================================================================== Journal References:
1. Elena Enax-Krumova, Ann-Christin Plaga, Kimberly Schmidt, O"zu"m S.

O"zgu"l, Lynn B. Eitner, Martin Tegenthoff, Oliver Ho"ffken. Painful
Cutaneous Electrical Stimulation vs. Heat Pain as Test Stimuli
in Conditioned Pain Modulation. Brain Sciences, 2020; 10 (10):
684 DOI: 10.3390/brainsci10100684
2. A. T. Lisa Do, Elena Enax-Krumova, O"zu"m O"zgu"l, Lynn B. Eitner,
Stefanie Heba, Martin Tegenthoff, Christoph Maier, Oliver Ho"ffken.

Distraction by a cognitive task has a higher impact on
electrophysiological measures compared with conditioned pain
modulation.

BMC Neuroscience, 2020 DOI: 10.21203/rs.3.rs-26882/v3 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/12/201221121736.htm

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