Pain Flashcards

1
Q

what is pain

A

unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage

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2
Q

what is pain influenced by

A

biological. social, cultural and emotional factors

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3
Q

what is sensing pain for

A

protective adaptation
rare genetic mutations in pain-sensing ion channels can cause congenital indifference to pain

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4
Q

what is acute pain

A

pain that lasts from a few minutes to less than 6 months

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5
Q

what is chronic pain

A

pain that lasts for more than 3 months

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6
Q

what communicates noxious stimuli to the brain

A

spinothalamic tract

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7
Q

describe peripheral sensation of pain

A

specialised nociceptive neurons sit in the epidermis
stimulus causes ion channels to open and depolarisation generates an action potential to pass the signal centrally
sensitisation increases the magnitude of the response to pain when the degree of noxious stimuli remains the same

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8
Q

what contributes to chronic pain

A

inappropriate sensitisation of ion channels

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9
Q

describe central modulation of pain

A

when the signal arrives at the thalamus, emotional, cognitive and sensory inputs come together and modulate the perception of pain

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10
Q

what is a possible explanation for why some people are more prone to chronic pain than others

A

variations in central pain modulation

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11
Q

what occurs after the noxious stimuli has been removed

A

under normal conditions, there is descending inhibition of pain sensation
emotions or anticipation of pain relief (placebo analgesia) can enhance this downregulatory system

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12
Q

what occurs in the periaqueductal grey matter

A

serotonin released here travels downwards and triggers endogenous opioid release in dorsal horn spinal cord interneurons
endogenous opioids reduce incoming pain pathway activity via opioid receptors (mu, kappa, delta) on inhibitory neurons
release of inhibition allows onward dopamine signalling, calming the pain stimulus and emotional response to pain

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13
Q

how is acute pain managed

A

promptly identify and treat underlying cause where possible
start at bottom of pain ladder, and work way up if pain still persists
if pain is very severe clinicians may start at top of pain ladder and work their way down
treat pain ‘around the clock’ with regular prescription, top-up with breakthrough dose as required
think about psychological factors, reassure and relax the patient

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14
Q

what is the pain ladder

A

bottom - non-opioid medication alone (paracetamol, NSAIDs)
middle - non-opioid medication and weak opioid (codeine) with or without adjuvant analgesic
top - non-opioid medication with strong opioid (morphine), with or without adjuvant analgesic
if starting at bottom review pain burden regularly and step up if pain persists
if starting at top, review response and step down or halt where possible to avoid adverse effects

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15
Q

what are features of neuropathic pain

A

pain in the absence of stimuli
painful sensation with innocuous stimuli (allodynia)
numbness
tingling (parasthesia)
feeling of insects crawling over the skin (formication)
abnormal sensation in affected areas (dysesthesia)

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16
Q

treatment for neuropathic pain

A

tricyclic antidepressants (amitryptiline) and SNRIs (duloxetine) act at the synaptic cleft
gabapentin and pregabalin
opioids (tramadol, morphine)
second-line patches (lidocaine, capsaicin)

17
Q

what is the mechanism of gabapentin and pregabalin

A

act on calcium channels pre-synaptically to reduce the release of pro-nociceptive neurotransmitters they decrease excitability, especially in the spinal cord

18
Q

what is the mechanism of action for opioids

A

manipulate dopamine signalling in the thalamus, brainstem and spinal cord

19
Q

how do second-line patches work

A

act upon the nociceptors in the epidermis
work to lower the firing of action potentials from skin to brain