My brain my pain
[Music]
[Applause]
hi
my name is laura and i hurt people for a
living
wow if that isn’t an icebreaker for the
next dinner party i don’t know what
is but what sounds like a catchy phrase
is actually the truth
i do work in pain research and that
includes applying painful stimuli to
consenting adults
to find out how pain works i’ve been
researching pain now for over 10 years
and i continue to be fascinated by it
every single day
but what makes pain such an interesting
and relevant topic to study
first of all pain is something we all
know
i guess it is safe to assume that each
and every one of you
knows how excruciating a toothache can
feel or
has experienced that dreadful second
when you hit your little toe at the edge
of the shower cabin
and expect that oncoming surge of pain
right
i know however
pain is also something we all need in
its acute form
it notifies us about a potential threat
to our body
and it protects us from more serious
injuries
if it weren’t for pain we would probably
just leave our hand on the hot stove
until it’s too late and the harm is done
do you smell that smells a bit burnt
does it
not a pleasant thought so
as this example tells you a healthy and
long life without pain
is just not possible pain obviously
works as a reliable alarm bell
which goes off whenever our
pain-sensitive skin receptors get
activated
you might assume now that this alarm
bell rings even louder
the more harmful the painful stimulus is
and in principle that’s also true still
the relationship between objective
painful stimulus
and pain experience is not an entirely
linear
or unchanging one in other words
even if the painful stimulus remains
exactly the same
our perception of it may vary from
person to person
from day to day or even from moment to
moment
imagine me having a toothache right now
i’m pretty sure i would still be able to
give this talk
i would be focusing on something else
thanks to adrenaline
but the same tooth egg might keep me
awake at night when there is nothing
else to distract me from it
making me regret that i didn’t make this
dentist appointment
what this example tells you is that pain
experience is not an objective process
instead it is influenced by our previous
experiences
by our expectations or by our current
focus of attention
already 250 years ago the painter gaspar
traversing illustrated this subjective
and
changeable nature in two of his
paintings
on the left you see a doctor performing
a surgical procedure
and this procedure is obviously very
painful because the patient needs to be
constrained and is opening his mouth
widely in agony
on the right side you see the same
surgical procedure being performed
but the presence and the caring
affection of the lady on the right
is obviously a real game changer here
and suddenly
the procedure doesn’t appear all so
painful anymore
i find this direct comparison in
traverses pictures quite amusing
partially because i know it is true it
is indeed incredible to witness
how much our pain experience our
subjective reality of pain can change
from one situation to the other
however that is not always amusing
because it is not always a good thing
there are situations where the gap
between objective painful stimulation
and subjective reality of pain can grow
so large
that it poses a problem and that is the
case in chronic pain
patients with chronic pain experience
continuous pain
sometimes without any physical injury
which could sufficiently explain what
they feel
in their case pain has lost its
protective function
and it continues to exist long after any
potential threat
to the body has ceased so chronic pain
might not be as omnipresent as acute
pain
but it is still surprisingly common 20
of the average adult population in
europe suffer from a chronic pain
condition
be it fibromyalgia arthritis
a migraine or lower back pain if i would
ask you to raise your hand if you are
one of these persons
i guess a lot of hands would raise up in
the air actually including mine
because i happen to suffer from a nasty
migraine several times per month
chronic pain does not only affect the
person who has to live with it
but also their family friends and social
network
chronic pain causes disability
preventing the people to work in their
jobs or
to do what they love and eventually
the consequences of chronic pain also
cause an economic burden to society
so the german healthcare system alone
they cost 38 billions of euros every
year
so what these statistical facts clearly
imply is that currently
we are obviously not able to treat
chronic pain in a satisfying manner
which would mean reducing the individual
suffering to a level
which does not interfere anymore with
daily affairs
now what can we do to change that as a
neuroscientist i say
if we want to be able to treat chronic
pain better
we have to understand chronic pain and
acute pain better
and to do that we have to take a closer
look at the brain
now let me start by telling you about a
study which nicely demonstrates
the importance of the brain in the
development of chronic pain
in this study the researchers observed
40 people
with an acute back injury over the
course of one year
these were generally healthy people who
just have happened to hurt their backs
they suffered from something we would
call a hexanshos in german
or lambago in english
during this one year 50 of the
participants recovered from the episode
of acute pain
while for the other 50 their pain turned
into chronic pain
if you looked at the backs of these
people you would not be able to tell any
difference
for all of them the injury had healed
however what did differ was their brain
activity
on the first visit the brains of all
patients
showed similar brain activity in regions
which are related to acute pain
processing
after one year the brains of the
patients who had recovered didn’t show
any pain related brain activity anymore
however in the brains of the patients
who did develop chronic pain
the activity had gradually shifted from
activity in the acute pain circuit
towards regions which are more related
to the processing of emotions
and effect so in a nutshell what
differentiated those patients who
recovered
from those who developed chronic pain
was not so much determined by their
affected body part
in this case the back but by what
happened in their brains
now how do these and other neuroimaging
studies make pain-related brain activity
visible and measurable one method you
can use whenever you want to know
where something happens in the brain is
functional magnetic resonance imaging
or in short fmri which is also
what the researchers did in the study
which i just told you about
fmri is a non-invasive measure of brain
activity
which indirectly measures neuronal
activity
via the increases and decreases of blood
flow
and these regional changes of blood flow
help us to pinpoint which brain regions
are more or less active
in comparison to a control group or
control condition
another method of neuroimaging which is
commonly used in pain research
also in our lab is the
electroencephalography
or in short eeg and eeg nicely
complements the method of fmri
as it measures neuronal activity
directly and it has a good temporal
resolution
which means it is your method of choice
whenever you want to know
when something happens in the brain
these and other neuroimaging methods
have already taught us some very
important lessons
and one of those lessons i’m going to
share with you today and that is
that there isn’t such a thing as a
single pain center in the brain
and that differentiates pain from our
other senses just like
hearing or seeing which do indeed rely
on some very focal brain areas
instead in pain processing several
regions in the brain are active
and they work together as a network to
create and shape
what we experience as pain some of these
regions are related to bodily awareness
others to emotional processing and even
others to the preparation
and execution of movement
now let us assume for a moment that the
brain is built to be
efficient not redundant if there is so
much going on during pain processing
it is reasonable to assume that the
different brain activity
in different regions of the brain is
also related to different
and complementary tasks in creating our
pain experience
and indeed brain research has begun
to identify brain activity which is more
closely related
to the objective stimulus
characteristics like the intensity or
duration of a stimulus
as opposed to brain activity which is
more related to our subjective pain
experience
what we actually feel and as we already
know
the painful stimulus and how we
experience it can differ widely from one
another
so this blooming knowledge fueled
another research question
and that is can we actually predict
someone’s momentary pain
just by looking at his or her brain
activity or in other words
can we develop an objective measure of
pain a biomarker
and equally important why do we even
want to develop such a biomarker for
pain
now what sounds like the academic idea
of a researcher
is actually highly relevant from a
clinical and practical point of view
until today if we want to quantify
someone’s pain
we have to rely on self-assessment
that means if we want to know whether
someone is in pain
we have to ask him or her about it now
don’t get me wrong
this is not a bad idea as a mentor of
mine always used to say half-jokingly
if everything else fails we can always
resort to talking to our patients
but that might be difficult whenever
communication is impaired
just think of patients who are suffering
from dementia
or who are unconscious on intensive care
units
or even small children in these cases an
objective measure of pain could
reasonably complement
their self-assessment and that is not
all
an objective measure of pain could also
be beneficial in the treatment of
chronic pain
just think back to the study i mentioned
earlier identifying those people at risk
of developing chronic pain
could already be helpful to start pain
therapy
before the pain has become chronic
but although pain research has
progressed a lot in recent years
we are currently not able to reliably
deduce someone’s momentary pain
just from looking at his or her brain
activity alone
developing a biomarker like this is
currently much sought after
and it’s a hot topic in the pain
community and beyond
in fact we ourselves are currently
conducting a large-scale study with
exactly that same goal
in our lab here in munich
so we might not be able to read a
person’s pain
just by looking at his or her brain
activity yet
however we have already learned
something fundamentally new
and important and that is that pain
originates in the brain
what we feel is only partially
determined by
the sensory input to our skin receptors
in large parts it is created
and shaped by processes in our brain
which take into account our previous
experience our current mood
and so much more in the case of chronic
pain
pain may even persist without any
sensory input
back pain does not originate in the back
and leg pain does not necessarily
manifest in the leg
it is widely acknowledged now by experts
in the field that chronic pain is not
only a symptom
but it is a disease in its own right
for many years doctors and patients
alike assume chronic pain to be
something invisible
and brain imaging has changed that
chronic pain is now not anymore
considered something
esoteric potentially imagined anymore
but as a physical condition with a
physiological basis
i hope to spread this message from the
labs of pain research to as many people
as possible
you might not be able to see a person’s
migraine the same way you see a broken
leg
at least not if you don’t happen to have
an mri scan or standing in the living
room
but it is there and it can be just as
debilitating
moreover i believe that understanding
the brain mechanisms underlying pain is
the key
for an optimized treatment of chronic
pain which could alleviate the suffering
of so many people
and we are just beginning to learn where
to look
thank you