A brief slideshow on pain, including a fascinating example of extreme perceived pain in the absence of tissue damage.

1. THE EXPERIENCE OF PAIN
A Question of Perception

2. A FAMILIAR EXPERIENCE
 Pain is often experienced in connection with
some form of physical trauma.
 As we grow up, this association is frequently
reinforced.
 For centuries, it was assumed that only
tissue damage triggered pain.

3. NOTABLE EXCEPTIONS
 Medical doctors and nurses frequently
noticed that soldiers injured in battle often felt
little or no pain until later.
 And sometimes, pain and other sensations
could still be felt in limbs that had been lost.
 These and other
phenomena cast
doubt on the old
explanations for pain.

4. DEFINITIONS
 In the 20th century, scientists and clinicians
studying pain from different perspectives
developed a taxonomy for discussing pain
and various manifestations/experiences of it.
 The International Association for the Study of
Pain (IASP) defines pain as…

5. PAIN (FULL DEFINITION)
An unpleasant sensory and emotional experience associated with actual
or potential tissue damage, or described in terms of such damage.
Note: The inability to communicate verbally does not negate the possibility that an individual is
experiencing pain and is in need of appropriate pain-relieving treatment. Pain is always
subjective. Each individual learns the application of the word through experiences related to
injury in early life. Biologists recognize that those stimuli which cause pain are liable to damage
tissue. Accordingly, pain is that experience we associate with actual or potential tissue damage.
It is unquestionably a sensation in a part or parts of the body, but it is also always unpleasant
and therefore also an emotional experience. Experiences which resemble pain but are not
unpleasant, e.g., pricking, should not be called pain. Unpleasant abnormal experiences
(dysesthesias) may also be pain but are not necessarily so because, subjectively, they may not
have the usual sensory qualities of pain. Many people report pain in the absence of tissue
damage or any likely pathophysiological cause; usually this happens for psychological
reasons. There is usually no way to distinguish their experience from that due to tissue damage
if we take the subjective report. If they regard their experience as pain, and if they report it in
the same ways as pain caused by tissue damage, it should be accepted as pain. This
definition avoids tying pain to the stimulus. Activity induced in the nociceptor and
nociceptive pathways by a noxious stimulus is not pain, which is always a psychological
state, even though we may well appreciate that pain most often has a proximate physical cause.
~ International Association for the Study of Pain (IASP) Taxonomy

6. PAIN (SUMMARIZED DEFINITION)
An unpleasant sensory and emotional experience associated
with actual or potential tissue damage, or described in terms of
such damage.
Key Points
 Pain is always subjective.
 Pain is always an emotional experience.
 Pain is often reported in the absence of tissue damage or any likely pathophysiological
cause, usually for psychological reasons.
 If reported in the same ways as pain caused by tissue damage, it should be accepted as pain.
 Activity induced in the nociceptor and nociceptive pathways by a noxious stimulus is not pain,
which is always a psychological state, even though we may well appreciate that pain most often
has a proximate physical cause.
~ derived from IASP Taxonomy

7. A PERCEIVED PAIN EXPERIENCE
 Despite no tissue damage,
the patient experienced
extreme pain and had to be
sedated.
 Case report from the British
Medical Journal (BMJ),
1995.
A builder aged 29 came to
the accident and emergency
department having jumped
down on to a 15 cm nail. As
the smallest movement of
the nail was painful he was
sedated with fentanyl and
midazolam. The nail was
then pulled out from below.
When his boot was removed
a miraculous cure appeared
to have taken place. Despite
entering proximal to the steel
toecap the nail had
penetrated between the
toes: the foot was entirely
uninjured.
- J P FISHER, senior house officer, D T HASSAN,
senior registrar, N O'CONNOR, registrar, accident
and emergency department, Leicester Royal
Infirmary.

8. HOW DID THIS PATIENT FEEL PAIN?
 Despite no tissue damage,
the patient experienced
extreme pain and had to be
sedated.
 Case report from the British
Medical Journal (BMJ),
1995.
 We need to look
at how the brain
perceives and
interprets
sensory input.

9. THE NEUROMATRIX THEORY OF PAIN
 Inputs include biological,
psychological, and social
factors.
 Outputs include all aspects
of how we experience and
respond to the world.
 Many different
forms of inputs
affect how the
brain interprets
incoming
sensory data to
create our
experience(s) of
reality.

10. BIOLOGICAL FACTORS IN PAIN
 Nociceptive input
is transmitted to
brain via
peripheral nerves
and the
spinothalamic
tract.
 Other forms of
sensorimotor
input are
received and
processed by
various parts of
the brain to
create a mental
image of where
pain occurs.

11. Figure 1 Schematic drawing of
the pathways between the
substantia nigra and pain-
processing areas
Wasner, G. & Deuschl, G. (2012) Pains in Parkinson disease—many
syndromes under one umbrella
Nat. Rev. Neurol. doi:10.1038/nrneurol.2012.54
Efferent pathways from the substantia
nigra project to pain-processing areas (red
boxes), as indicated by black arrows.
Together with further pain-processing
areas (yellow boxes), these brain
structures form a network that is essential
for transmission of nociceptive input and
central pain processing, as indicated by red
dotted lines.
Sensory cortices (S1 and S2) are
suggested to be involved in the descriptive
component of pain, whereas the anterior
cingulate and prefrontal cortices seem to
be essential for the affective dimension of
pain.
Abbreviations: S1, primary sensory
cortex; S2, secondary sensory cortex.
NEUROBIOLOGY OF PAIN

12. PSYCHOSOCIAL FACTORS OF PAIN
 Conscious
cognition,
including
thoughts and
feelings
 Unconscious
(conditioned)
responses to
various stimuli
 Unconscious
stimuli without a
conditioned
response  Context provided by psychological and
social factors play an important role in
determining how biological factors are
interpreted.

13. PSYCHOSOCIAL FACTORS OF PAIN
 The frontal
cortex and
temporal
lobes are of
primary
importance in
determining
the
psychosocial
context.
 Context provided by psychological and
social factors play an important role in
determining how biological factors are
interpreted.

14. HOW DID THIS PATIENT FEEL PAIN?
 Despite no tissue damage,
the patient experienced
extreme pain and had to be
sedated.
 Case report from the British
Medical Journal (BMJ),
1995.
The patient would have…
 Felt the sensations of
landing and possibly of
having an object
penetrate his boot
 Heard the sound of his
landing
 Seen a huge nail
through his boot
 Seen and heard the
reactions of his
coworkers

15. HOW DID THIS PATIENT FEEL PAIN?
 Despite no tissue damage,
the patient experienced
extreme pain and had to be
sedated.
 Case report from the British
Medical Journal (BMJ),
1995.
The patient would have…
 Expected that a nail
penetrating his boot
would probably
penetrate his foot
 Perceived that his foot
had been punctured by
the nail
 Had both conditioned
and unconditioned
negative responses to
being punctured by a
sharp object

16. HOW DID THIS PATIENT FEEL PAIN?
 Despite no tissue damage,
the patient experienced
extreme pain and had to be
sedated.
 Case report from the British
Medical Journal (BMJ),
1995.
 This patient
perceived an
experience of what
seemed to have
happened, and
responded to that
 His pain was
created by his
brain, despite the
lack of any
nociceptive input
from his peripheral
nerves

17. HOW DID THIS PATIENT FEEL PAIN?
 This patient
perceived an
experience of what
seemed to have
happened, and
responded to that,
even though it was
not real
 His discomfort was generated solely
from psychosocial factors, yet was as
intense as if his foot had actually been
punctured

18. A FASCINATING ORGAN
 Understanding the Brain: The
Neurobiology of Everyday Life with
Peggy Mason, Ph.D. is a great
Coursera class
 The course provides a foundation for
understanding the roles and
relationships of the various parts of
the nervous system in relation to
itself, to other organs/systems, and
the world around us.
 Though pain was not addressed in
detail, the course material covered
sensorimotor inputs, perception,
memory, and cognition, which are
essential for analyzing the biological
and psychosocial elements of pain.

19. FOR MORE INFORMATION ON PAIN
 Video “Why Things Hurt” – Lorimer Mosely, http://youtu.be/gwd-
wLdIHjs
 Book Explain Pain by David Butler and Lorimer Mosely, from
http://NOIgroup.com
 Paper “Pain” by Ronald Melzack and Joel Katz,
http://onlinelibrary.wiley.com/doi/10.1002/wcs.1201/full
 Commentary on “Pain” paper by Diane Jacobs, PT,
http://humanantigravitysuit.blogspot.com/2013/05/melzacks-and-
katz-new-paper-pain-part-1.html
 Paper “Getting the pain you expect: mechanisms of placebo,
nocebo and reappraisal effects in humans” by Irene Tracey,
http://www.nature.com/nm/journal/v16/n11/full/nm.2229.html

20. CONTACT
 For more information about this slideshow,
contact Jason Erickson via
JasonEseminars@gmail.com