Pain
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Types of Pain

Acute Pain
– Complex combination of sensory, perceptual, &
emotional experiences as a result of a noxious
stimulus
– Mediated by rapidly conducting nerve pathways &
associated with increased muscle tone, heart rate, &
blood pressure (sympathetic nervous system
response)
– Intensity depends of the degree of injury
– Serves as a protective function
– Tx – reduce inflammation & modify transmission of
pain
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Types of Pain

Chronic Pain
– Starts as acute pain but persists ≥ 3 – 6
months
– Continues even after noxious stimulus is
absent (unlike chronic inflammation)
– Associated with physical (strength,
endurance), psychological, & social
dysfunction
– Source maybe increased sympathetic
response (increased sensitivity of nociceptors)
or financial gain
– Tx – decrease risk of chronic pain by using
physical agents &/or meds to tx acute pain
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Types of Pain

Chronic pain
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Types of Pain

Referred Pain
– Felt at one area distant from the source
 Ex – spinal nerve root impingement, angina
– Pain may be referred from a nerve to innervation site
or from different areas of the same dermatome
– Clinicians should not “chase” pain
– Rule-out proximal sources of pain
– Determine the structure(s) that are responsible for
the pain
 Rotator cuff injuries can refer pain to the lateral &
upper arm
 Kidney pathologies can refer pain to the low back
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Mechanisms of Pain Reception
and Transmission

Specificity Theory
– Type of pain depends
on the stimulation of
specific nerve endings

Pattern Theory
– Type of pain depends
on intensity or
frequency of
stimulation of
receptors that also
respond to touch,
pressure, or
temperature
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Mechanisms of Pain Reception
and Transmission

Pain Receptors
– Nociceptors can be
activated by thermal,
mechanical, or
chemical stimuli
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Mechanisms of Pain Reception
and Transmission

Peripheral Nerve
Pathways
– C fibers (80%) – cause
sensation of dull,
throbbing, aching, or
burning pain
– A-delta fibers (20%) –
cause sharp, stabbing,
pricking pain
– Both types of fibers
may or may not be
stimulated
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Mechanisms of Pain Reception
and Transmission

Pain-spasm cycle
– Muscle guarding
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
Whiplash injury
– Muscle guarding
– “Protective guarding”
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Pain Modulation and Control

Gate Control Theory
– Proposed by Melzack &
Wall (1965)
– Degree of pain is
determined by the
balance of excitatory
and inhibitory inputs
to the spinal cord
– Increased activity of
the non-nociceptive
fibers causes inhibition
of nociceptive fibers
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Pain Modulation and Control

Gate Control Theory
– Physical agents and interventions “close the
gate” for pain by activating nonnociceptive
nerves
– Ex’s – traction, compression, & massage
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Pain Modulation and Control

The Endogenous Opioid System
– Pain can be modulated by endogenous
opioids
– Opioids bind to opioids receptors in the
nervous system which inhibits pain
– Electrical stimulation has been shown to
release endogenous opioids
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Measuring Pain

Visual Analog & Numeric
Scales
– VAS – draw a line on
the scale to indicate
the present level of
pain
– Numeric scale – rate
pain from 0-10/10 or 1
to 100
– Face Scale - Used for
individuals who have
difficulty
understanding the VAS
and numeric scales
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Measuring Pain

Comparison with a Predefined Stimulus
– May allow greater intrasubject & intersubject
reliability
– The subject compares the present pain to a
predefined stimulus
 Tourniquet pain, electrical pain, thermal pain, or
pressure pain
 You can imagine the limitations to this form of
assessment!!!
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Measuring Pain

Semantic Differential
Scales
– Consists of word lists
and categories that
represent various
aspects of pain
– McGill pain
questionnaire
– Attempts to quantify
pain
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Measuring Pain

Other Measures
– Daily activity/pain logs
– Body diagrams
– Open-ended,
structured interviews
– Pain response to
examination
tests/measures
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Pain Management Approaches

Pharmacological Approaches
– Systemic Analgesics
– Non-steroidal anti-inflammatory drugs
(NSAIDS)
– Acetaminophen
– Opiates
– Antidepressants
– Spinal Analgesia
– Local Injection
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Pain Management Approaches

Physical Agents
– Cryotherapy – reduce local metabolism & slow
production of histamine, bradykinin, &
prostaglandins
– Cryotherapy, thermotherapy, & traction
stimulate non-nociceptive nerve fibers
– Physical agents have some advantages over
medications
 Ex – less side-effects and can be readily used by
the patient (ice pack or hot pack)
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Pain Management Approaches

Multidisciplinary Pain Treatment Programs
– Teams consist of the patient, families, PTs,
MDs, RNs, psychologists, etc
– Management techniques include:
medications, physical agents, therapeutic
exercise, &/or psychological intervention
 Pain Clinics
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