Pain Flashcards
(19 cards)
What is Phantom pain?
Pain sensation without any sensory input
What are the suggested causes of Phantom pain?
Cortical Reorganisation:
In homunculus
Central sensitisation: Permanent change in synaptic structure of dorsal horn
What receptors do endogenous opiates interact with to form Endogenous analgesia?
Opiate receptors on the nociceptor synaptic terminal. Prevents substance P release.
What is hyperalgesia?
An increased sensitivity to pain usually bc tissue has been damaged before.
What may be the result of chronic nociceptive pain?
Neuropathic/mixed pain
What may be the adverse effects of acute pain? (THINK STAB WOUND)
CV stress, respiratory compromise, hypercoagulation
Where do non-opioids act?
Nociceptors
Where do opioids act?
2 sites
1) Hyperpolarise post synaptically - reduce AP potential.
2) Presynaptic reduce transmission
What non-opioid prevents prostaglandin formation through the inhibition of COX?
NSAIDs
What non-opioid has a toxic liver damage risk?
Paracetamol
What activates the endogenous analgesic system?
Opioids
What are some of the side effects of opioids?
Nausea, vomiting, constipation, dizziness, somnolence, dry skin.
What opioids should be avoided with renal failure?
Morphine and codeine, toxic metabolites accumulate.
Where do spinal opioids act?
Dorsal horn of spinal cord.
What is neuropathic pain?
Pain arising bc of damage to nervous system.
Hyper excitable spinal cord is one mechanism of neuropathic pain, what is it?
Trauma or damage, increases the nociceptor input to the dorsal horn = more sensitive to pain (hyperalgesia)
What is the mode of action of antidepressants?
Prevent re-uptake of noradrenaline and serotonin
What are the most effective antidepressants?
Tri-Cyclic agents. Serotonin re-uptake inhibitors quite useless.
What is the mechanism of Gabapentin?
Ca2+ channel blocker - stops excitatory neuropathic pain (not nociceptive)
