4 – Central Modulation of Pain

Question 1

Central modulation of pain transmission

Answer 1

• Conditions where level of pain experienced is LESS than what would be expected
  o Emotional state
  o Attention
  o Expectations
  o Exposure to chronic pain
  o Altered pain threshold/experience

Question 2

Periaqueductal grey matter (PAG)

Answer 2

• Pain-modulating region in the brain (don’t want to be hyperexcitable)
• Receives info from relay spinal neurons AND higher cognitive structures
• Sends descending signals to the relay neurons in the SC

Question 3

• Receives info from relay spinal neurons AND higher cognitive structures (PAG)

Answer 3

o Provide info about emotional state, etc
o *integrates the info from both
o *RISK ASSESSMENT

Question 4

• Sends descending signals to the relay neurons in the SC (PAG)

Answer 4

o Release NE which binds to the NE alpha-2 receptors on the pre- and post-synaptic neuron
o REDUCES the amount of signal being sent back up
>Prevents the AP from happening

Question 5

Alpha-2 agonists

Answer 5

• Xylazine
• (dex)medetomidine
• *bind to NE receptors and block the pain transmission
  o Decrease excitability of cells (ex. mimicking the presence of NE)

Question 6

Opioid receptors

Answer 6

• On post-synaptic cell of pain relay neuron
  o When bound=inhibit cell from making an AP=can’t send pain signal to the CNS=perception of pain is reduced
• *use opioids: bind receptors at SC and higher level structures (PAG)

Question 7

Approach to analgesia

Answer 7

• Drug mechanism of action
• Dose
• Pre-emptive analgesia
  o Not always possible
  o Try to reduce amount of noxious stimulus they will perceive later on