Pathophysiology of Pain and Pain Assessment

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Pathophysiology of Pain and Pain Assessment
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Pain is.

• Sensory
• Emotional
• Cognitive

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. . . . 3 Hierarchical Levels

• Sensory-discriminatory component (location,
  intensity, quality)
• Motivational-affective component ( depression,
  anxiety)
• Cognitive-evaluative component (thoughts of
  cause, significance of the pain)

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Who Has Pain?

• 90 of adults more than one day a month
• 42 report pain everyday
• 9 of adults suffer moderate -severe chronic
  non-cancer pain (75 million Americans)

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Pathophysiology

• Nociceptive Pain Mechanisms
• Neuropathic Pain Mechanisms
• Psychological or Idiopathic Pain Mechanisms

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Nociceptive

• Receptor stimulation (by process causing tissue
  injury)
• Normal activation (of nociceptive system)
• Afferents A-delta and C-fibers, to dorsal horn,
  ascending neural pathways, thalamic,other brain
  structures
• Acute and/or chronic inflammation
• Sensory/discriminatory, motivational/affective,
  cognitive/evaluative

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Nociceptive Pain Modulation

• Endorphinergic endogenous opioid compounds
  acting at mu, delta, kappa receptors
• Opioid associated systems that regulate
  homeostasis, response to stress, and pain
• Serotonin, norepinephrine and other
  neurotransmitters also involved

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Types of Nociceptive Pain

• Acute and Chronic
• Somatic localized,described as aching,
  throbbing, stabbing (i.e. arthritis, bone mets)
• Visceral generalized, described as cramping,
  gnawing, varying intensity, often referred ( I.e.
  bowel obstruction)

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Neuropathic Pain Mechanisms

• Pathophysiologic changes in the peripheral or
  central nervous system
• Changes become independent of the initial injury
  or damage, and can sustain a chronic pain state
• Often described as burning, lancinating,
  electrical

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Neuropathic Pain Altered Pain Responses

• Allodynia pain induced by light touch
• Hyperalgesia increased response to noxious
  stimuli
• Hyperpathia exaggerated responses to painful
  stimuli, with continued sensation of pain after
  the stimulation has ceased

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Psychological or Idiopathic Pain

• We all have pain, yet not everyone suffers
• The patients psychological state contributes
  significantly to pain and suffering pain is
  objective and subjective
• Affective and psychological disorders should be
  assessed and treated
• psychogenic pain

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Initial Pain Assessment

• History and Physical Exam
• Psychosocial Assessment
• Diagnostic work-up, or review of previous
  diagnostic studies and consultations
• Assessment should be ongoing, individualized, and
  documented
• The patient self-report is the gold standard in
  assessment

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Most Experts Believe

• That repeated evaluation of the
• same painful site in a patient with
• long-standing chronic pain rarely
• yields useful results and may divert
• attention from symptom control and
• functional restoration.

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Assessing Pain Character and Intensity

• Select a method, incorporate it
• Unidimensional Pain Scales
• Verbal Rating Scale (none, mild)
• Numeric Rating Scale (010)
• Visual Analog Scale (10cm line)
• Faces, Color, other scales
• Multidimensional Pain Scales
• McGill Pain Questionnaire
• Memorial Pain Assessment Card
• Brief Pain Inventory

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Post-Test
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Which of the following are components of the pain
experience?

• a. Sensory-discriminatory
• b. Motivational-affective
• c. Cognitive-evaluative
• 1. a only
• 2. a and b
• 3. a and c
• 4. All of the above

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True or False?

• 1. Nociceptive pain involves normal activation by
  noxious stimuli
• 2. Neuropathic pain involves injury to
  peripheral, central nervous system
• 3. Nociception with chronic inflammation and
  persistent tissue injury can cause chronic pain
• 4. Pain that appear idiopathic need not be fully
  investigated, as there is no physical cause

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Which are components of initial pain assessment?

• a. Detailed history, including pain
  characteristics and intensity
• b. Physical exam, with emphasis on the
  neurological examination
• c. A psychosocial assessment
• d. An appropriate diagnostic work-up
• 1. a only 2. a and b 3. a,b,c 4. all

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Which is the best indicator of a patients pain?

• a. Patient self-report
• b. Caregiver accounts
• c. Evaluation of facial expressions
• d. Sympathetic signs and symptoms
• 1. a 2. a and b 3. a,b,c 4. all

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Which of these tools does not provide a measure
of pain intensity?

• a. Faces Pain Scale
• b. Numeric Rating Scale
• c. Visual Analog Scale
• d. Brief Pain Inventory
• 1. a only 2. d only 3. None 4. all