Intro To Pain Flashcards
At what period does acute pain become termed chronic pain?
12 weeks
What period of time is termed ‘sub-acute’ Pain?
<6 weeks
Which are the main afferent pain fibres that transmit pain from the nociceptors?
Where do they travel to and synapse?
A delta and C
They synapse with secondary afferent neurones in the dorsal horn root ganglion
What is the main pain pathway (tract)?
Is it anterior or posterior sub-division?
The lateral spino-thalamic pathway
What does the thalamus do?
Relays sensory information
What division of the brain is the thalamus in?
Diencephalon
Where are opioid receptors located with respect to the structure of nerves?
Nerve terminals
What are the advantages of multi-modal analgesia?
1) opioid sparing = if benzo is used, opioid can be reduced by 20-30%
2) analgesics work synergistically
3) better side effect profiles
Name the weakest 2 opioid.
Tramadol
Codeine - weakest
Name the strongest opioids, from morphine upwards.
Morphine Oxycodone Methadone Fentanyl Remifentanyl
What is the other name of paracetamol?
Acetaminophen
What are the 2 non-opioid drugs for pain relief?
Paracetamol
NSAIDS
What are all other drugs that aid pain relief but do not treat it called?
Adjuvants
What is central sensitization?
Constant pain and nociception input remodels the way it is processed
What is allodynia?
Pain sensitization to things that are not normally painful
What is hyperalgesia?
Painful stimuli becomes increasingly more painful
What is the main excitatory neurotransmitter in the CNS?
Glutamate
What is the main inhibitory neurotransmitter in the CNS?
GABA
What is the NMDA receptor?
A glutamate receptor
Name an NMDA receptor antagonist.
Ketamine
What is pharmacokinetics?
What the body does to the drug
What is pharmacodynamics?
What the drugs do to the body
Name the 4 main parts of pharmacokinetics.
Absorption
Distribution
Metabolism
Excretion
What class of drug is amitriptyline?
Tricyclics antidepressant
What class of drug is pregabalin/gabapentin?
Anticonvulsant
What are anticonvulsants and tricyclics antidepressants used for other than their main uses?
Neuropathic pain
What receptors are found in nociceptors?
What triggers them?
TRPV1
They are triggered by temp/pH/capsasin
Where do the primary and secdary afferent neurones in the spinothalamic tract decussate?
At level of entry (or 1-2 spinal nerve segments above)
What are the 2 receptors for glutamate called?
AMPA
NMDA
What are substance P receptors called?
NK receptors
Where are opioid receptors located in relation to the synapse and what do they do when activated?
They are pre-synaptic
They hyperpolarize cells by opening K+ channel and also block Calcium influx, which in turn prevents neurotransmitter release
Which neurotransmitter is both excitatory and inhibitory?
Dopamine
What is the main inhibitory neurotransmitter in descending pain pathways?
5-HT
