Introduction to Pain
Kevin Ozaki, PT, DPT, OCS
DPT 732
California State University Long Beach
College of Health & Human Services
Department of Physical Therapy
Key Definitions: IASP
Noxious Stimuli: A stimulus that is damaging or threatens damage to normal tissues.
Nociceptive Stimulus: An actually or potentially tissue-damaging event transduced and encoded by
nociceptors.
Peripheral Sensitization: Increased responsiveness and reduced threshold of nociceptive neurons in the
periphery to the stimulation of their receptive fields (1st order neurons: A-delta and C-fiber nociceptors)
Central sensitization: Increased responsiveness of nociceptive neurons in the central nervous system to
their normal or subthreshold afferent input (2nd order neuron: Nociceptive Specific and Wide-Dynamic Range
Neurons)
Hyperalgesia: Increased pain from a stimulus that normally provokes pain
Allodynia: Pain due to a stimulus that does not normally provoke pain
Key Definitions: Pain Types (Not a Medical Diagnosis)
Nociceptive Pain: Pain that arises from actual or threatened damage to non-neural tissue and is due to
the activation of nociceptors
Peripheral Neuropathic Pain: Pain caused by a lesion or disease of the peripheral somatosensory
nervous system
Nociplastic Pain: Pain that arises from altered nociception despite no clear evidence of actual or
threatened tissue damage causing the activation of peripheral nociceptors or evidence for disease or lesion of
the somatosensory system causing the pain.
What is Pain?
https://docs.google.com/document/d/1xHenEbkUc4eY2kiirmeUC62nLJSICVRs7mNYbFj19TA/edit?usp=sharing
Pain is Always Individualized
Pain
”AN UNPLEASANT SENSORY AND
EMOTIONAL EXPERIENCE
ASSOCIATED WITH, OR
RESEMBLING THAT
ASSOCIATED WITH,
ACTUAL OR POTENTIAL
TISSUE DAMAGE.”
INTERNATIONAL ASSOCIATION FOR THE STUDY OF
PAIN (2020)2
PROTECTION
6
Pain is a Protector
”AN UNPLEASANT
SENSORY AND
EMOTIONAL
EXPERIENCE
ASSOCIATED WITH, OR
RESEMBLING THAT
ASSOCIATED WITH,
ACTUAL OR POTENTIAL
TISSUE DAMAGE.”
Pain = Protection
Twin Peaks: Pain Becoming
2
OverProtective
Actual or potential tissue injury
RESEMBLING actual or
potential tissue injury
Short term: aides in recovery
Integrated Pain
Management Department
9
Long Term: inhibits recovery
Pain is Always Real, but can
become OverProtective and
thus the relationship
between pain and tissue
injury is less clear.
What Causes Pain?
https://docs.google.com/document/d/10376FdQc0MCYdhfvJIK9QWcg2su69mci6K-STjssCRU/edit?usp=sharing
Kahoot: Neurophysiology of Pain
Questionnaire
Cartesian Model of Dualism
Dualism: Separation of Mind and Body
Once “pain” receptors are activated, one
will experience pain
The Pain Pathway
Nociceptive Pathway
The BRAIN will
decide what to do
with the “danger”
signals based on…
Pain Believes
PAST EXPERIENCES
WITH THE SPECIFIC
DANGER SIGNAL(S)
If enough evidence of danger
is detected and a need for
PROTECTION is needed then
you will experience pain
Current
mood/emotions
Pain Self-Efficacy,
Psychological Distress,
Pain-Related Fear,
Catastrophization3
Past experiences
with environmental
information
Expectations/motivations/value
Dorsal Horn: Descending Inhibition or Excitation
Mature Organism Model4
1.
Pain is an output, not an input
a.
Pain is just one of the many protective
outputs/responses/behaviors
b.
Immune, neuroendocrine, autonomic
nervous system, motor system, cognitive,
emotional, etc
2.
Nociception alone is not sufficient or necessarily
needed to experience pain
3.
Having pain is ultimately decided by the Brain
4.
Thoughts, emotions, and moods are nerve
impulses that can start the pain cycle
(descending modulation )
•Gifford, L.S., Pain, the tissues and the
nervous system. Physiotherapy, 1998. 84: p
27-33
Biopsychosocial Model
Water
Bucket
Analogy
Biological/Physical
a. Genetics
b. Systemic disease
c. Tissue capacity
d. Systemic inflammation (sleep, stress,
exercise, nutrition)
Psychological/Cognitive
a. Stress
b. Psychiatric Disorders
c. Pain-related
unhelpful beliefs and
behaviors
d. Expectations
Social/Environmental
a. Health care system
b. Work environment
c. Family support
d. Resources in the
community
Key Points
Pain is always a real and an individualized experience (may not be
objectifiable)
Pain is always protective (may that be in the present of an actual or
potential injury), but does not always indicate tissue injury/damage
Tissue damage/injury and/or nociception does not automatically
lead to pain. The brain will decide based on the need for protection
of that body region
Key Points (Continued)
The longer pain persists, the more protective your “pain
system” will be and the relationship between pain and tissue
injury is less clear
Pain is multifactorial (biopsychosocial influences)
Focus on the Person (and not just their pain)
References
1.
2.
3.
Terminology: International association for the study of pain. International Association for the Study of Pain (IASP).
(2022, April 19). Retrieved September 17, 2022, from https://www.iasp-pain.org/resources/terminology/
Butler, D. S., Moseley, G. L., & Butler, D. S. (2019). Explain pain supercharged: The Clinician's Manual. Noigroup
Publications.
Gifford, L.S., Pain, the tissues and the nervous system. Physiotherapy, 1998. 84: p 27-33