Acute Pain + Analgesia 2 Flashcards

1
Q

How is pain modulated?

A
  • Involves multiple descending modulatory pain pathways that can have excitatory or inhibitory effects
  • Endogenous pain modulation explains variation how ppl perceive + report pain
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2
Q

Which inhibitory NT’s are involved in modulation of pain?

A
  • Endogenous opioids (encephalin + endorphins) -> prevent release of excitatory NT’s = neuropeptide + sub P
  • Serotonin (5-HT)
  • GABA
  • Noradrenaline
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3
Q

What is involved in the descending endogenous pain modulatory system?

A
  • PAG = key in pain-inhibition system
  • Some descending pathways facilitate pain + contribute to chronic pain
  • Higher cortical brain systems contribute
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4
Q

What is the role of PAG?

A
  • Primary control centre for descending pain modulatory system
  • Receives info from ascending pain + temp fibres of spinothalamic tract
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5
Q

Describe the role of PAG

A
  1. PAG activates encephalin - releasing neurons
  2. = release of serotonin which descends to dorsal horn + binds to substantia gelatinous interneurons
  3. activated interneurons release endogenous opioid NT’s which bind to mu opioid receptors on A-delta + C-fibres
  4. = inhibit release of Sub P
  5. Activation of cortical regions inhibit or facilitate pain processing
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6
Q

How does attention to pain affect how it is experienced?

A
  • Focus on pain = perceived as more intense
  • Attentional distraction reduces pain related Brian activity in S1, S2 + thalamus and increases activity in PFC, ACC + PAG
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7
Q

Explain cognitive appraisal of pain

A

Pain intensity reduced when pain perceived to be controllable

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8
Q

What effect does the acute light//flight stress response have on pain?

A

Dampens pain via release of noradrenaline + activation of PAG and endogenous opioids

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9
Q

What effect does chronic stress and negative emotions have on pain?

A

Increase pain intensity + reduce sense of perceived control over pain

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10
Q

Explain the placebo effect in regards to pain

A
  • Expectation of pain relief = powerful analgesic effect

- Positive expectation activates descending pain inhibition systems (inc. PAG)

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11
Q

Explain why patients experience chronic pain

A
  • Dysfunctional descending inhibitory system or activated/enhances descending facilitatory system
  • Alterations to higher level brain systems (PFC,ACC, PAG)
  • Generation + maintenance of central sensitisation states + hyperalgesia (dorsal horn implicated)
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12
Q

What is seen in the grey matter density of those who experience chronic pain?

A
  • Reduced neocortical grey matter volume

- Brain atrophy

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