Chronic pain

Question 1

describe chronic pain prevalence

Answer 1

3.24million aussies
53.8% are women
restricts activitis for 56%, 68.3% are working age
prevalence will inc 5.23 2050

Question 2

what is pain definition + chronic pain

Answer 2

unpleasant, sensory, emotional associated with or resembling that associated with actual tissue damage
chronic pain persists or recurs for longer than 3 months

Question 3

why do we need pain

Answer 3

info about potential damage, actual damage, recovery process

Question 4

describe chronic nociceptive, neuropathic, nociplastic pain

Answer 4

nociceptive = inflam/tissue damange (osteoarthitis)
neuropathic = damage pns/cns (migraine, MS)
nociplastic = pain arising altered function pain-related sensory pathways in pns/cns (fibromyalgia, lower back pain)

Question 5

what is primary pain + egs

Answer 5

chronic pain in 1+ areas that persists 3+ months + emotional distress, functional disability
chronic widespread pain, regional pain, headache + orofacial, primary visceral + musculoskeletal

Question 6

difference between pain and nociception

Answer 6

nociception detects potential/actual harm NOT measure pain
dorsal root ganglion -> spinal cord -> brain neurons for conscious awareness

Question 7

Is there only 1 type of nociceptor?

Answer 7

NO
eg there is mechanical allodynia (P2X3)
thermal hyperalgesia (TrpV1)

Question 8

what has to be activated to elicit pain

Answer 8

small unmyelinated + lightly myelinated nociceptors

Question 9

what type of threshold do nociceptors have

Answer 9

super high, high intensity stimuli
many potential stimuli

Question 10

describe the structure of nociceptors
eg why redness when scratch

Answer 10

not just afferent for modulation/processing, but also releases things as neurogenic inflammation upon stimulation eg sub P, ATP

Question 11

different types of nociceptive neurons

Answer 11

A & C fibres
can be polymodal, CMH, AM, silent
can be peptidergic, non-peptidergic (lab animals)

Question 12

where do sensory inputs/motor outputs go

Answer 12

sensory input = dorsal horn
motor outputs = ventral horn

Question 13

where do nociceptive fibres terminate

Answer 13

defined areas of the spinal cord
lamina I + 2 (upper section, grey matter)

Question 14

can you modulate nociceptive processing in the spinal cord?

Answer 14

yes
grabbing area of pain activated skin mechanoreceptors
act on inhibitory interneurons to weaken signal sent to thalamus

Question 15

describe pain signalling in brain

Answer 15

1st neurons DRG neurons
end and synapse on neurons on the dorsal horn (2nd neuron)
projection neurons of neuron 2 cross to other side
travels via spinothalamic tract (3rd neuron)

Question 16

describe ascending fibres

Answer 16

spinothalamic tract - sensory discriminative = 1st pain
fibres ending in PBN - affective emotional 2nd pain

Question 17

describe descending fibres

Answer 17

important for placebo effect, pain inhibition after severe injury
release serotonin and noradrenalin

Question 18

how to stop chronic pain?

Answer 18

multimodal:
change in lifestyle eg exercise, sleep, weight reduction
pharmacological therapies
physio
psychotherapy (cognitive behavioural therapy)

Question 19

what drugs can be used for chronic neuropathic pain

Answer 19

anti-epileptic (gabapentine, pregabaline)
analgesic antidepressants (tricyclic antidepressants (amitriptyline)), serotonin reuptake inhibitors (duloxetine)

Question 20

describe chronic non-neuropathic pain drugs

Answer 20

NSAIDs
opiods

Question 21

what’s the problem with opioids

Answer 21

dont work after 20 days
need higher sensitivity
big side effects with increased dosage

Question 22

describe the receptors that opioids act on

Answer 22

mu-opiate = beta endorphin endogenous ligand (euphoria, sedation, addiction)
delta = enkephalin endogenous ligand (supra +spinal analgesia)
kappa = dynorphin A endogenous ligand (supra + spinal analgesia, diuresis respiratory depression)

Question 23

where do we find the opioid receptors

Answer 23

everywhere there is pain signalling at DRG
peri aquaductal grey
processing areas in cortex/cortical areas

Question 24

how to treat non-neuropathic chronic pain

Answer 24

non-steroidal anti-inflam drugs = NSAIDs
ibuprofen, aspirin (acetylsalicylic acid), paracetamol (acetaminophren)
block cyclooxygenases, block prostaglandin synthesis, activate endogenous cannabinoid system

Question 25

what procedures can treat chronic pain

Answer 25

minimally invasive:
steroid injections, radiofrequency ablation (kill nerve fibres), spinal cord stimulation, DRG stimulation

Question 26

describe the project research for monitoring pain

Answer 26

serum -> pain sensing cells -> biochip -> detect -> support diagnosis and monitroing for specific type of pain
AND
isolating exosomal miRNA from CSF to investigate presence of unique markers of pain