Acute Pain + Analgesia 2 Flashcards
How is pain modulated?
- Involves multiple descending modulatory pain pathways that can have excitatory or inhibitory effects
- Endogenous pain modulation explains variation how ppl perceive + report pain
Which inhibitory NT’s are involved in modulation of pain?
- Endogenous opioids (encephalin + endorphins) -> prevent release of excitatory NT’s = neuropeptide + sub P
- Serotonin (5-HT)
- GABA
- Noradrenaline
What is involved in the descending endogenous pain modulatory system?
- PAG = key in pain-inhibition system
- Some descending pathways facilitate pain + contribute to chronic pain
- Higher cortical brain systems contribute
What is the role of PAG?
- Primary control centre for descending pain modulatory system
- Receives info from ascending pain + temp fibres of spinothalamic tract
Describe the role of PAG
- PAG activates encephalin - releasing neurons
- = release of serotonin which descends to dorsal horn + binds to substantia gelatinous interneurons
- activated interneurons release endogenous opioid NT’s which bind to mu opioid receptors on A-delta + C-fibres
- = inhibit release of Sub P
- Activation of cortical regions inhibit or facilitate pain processing
How does attention to pain affect how it is experienced?
- 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
Explain cognitive appraisal of pain
Pain intensity reduced when pain perceived to be controllable
What effect does the acute light//flight stress response have on pain?
Dampens pain via release of noradrenaline + activation of PAG and endogenous opioids
What effect does chronic stress and negative emotions have on pain?
Increase pain intensity + reduce sense of perceived control over pain
Explain the placebo effect in regards to pain
- Expectation of pain relief = powerful analgesic effect
- Positive expectation activates descending pain inhibition systems (inc. PAG)
Explain why patients experience chronic pain
- 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)
What is seen in the grey matter density of those who experience chronic pain?
- Reduced neocortical grey matter volume
- Brain atrophy