Week 10: Pain Flashcards

1
Q

What is pain?

A
  • an unpleasant sensory AND emotional experience associated with actual or potential tissue damage or described in terms of such damage
  • measurement is subjective
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2
Q

What is the area that lights up as you imagine pain?

A

the insula cortex (behind the lateral sulcus)

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3
Q

What are the components of the pain matrix?

A

Sensory/discriminative:

  • thalamus
  • somatosensory cortex

Affective:

  • brain stem
  • limbic system
  • amygdala
  • hippocampus
  • basal ganglia
  • pre frontal cortex
  • insula

Associative:
-posterior parietal cortex

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4
Q

Which area in the brain is responsible for the visceral nature of pain?

A

the brainstem as it controls autonomic functions of the body e.g heart rate, GI

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5
Q

Which pathway is pain transmitted through?

A

the lateral spinothalamic tract

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6
Q

How is excessive pain disproportionate to injury?

A
  • pain is worse if patient is tired/ anxious

- suggestion that something is going to be very painful makes it painful

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7
Q

What is a nocebo?

A

delivering negative information when given treatment e.g saying a LA cream will increase pain when it won’t

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8
Q

How is pain modulated?

A

You can become more or less sensitive to pain:

  • gate control theory of pain or descending inhibitory pain fibres
  • these fibres come down from the brain and act to inhibit pain
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9
Q

What type of fibres do nocioceptors send?

A

Ad and C fibres

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10
Q

What happens when inhibitory interneurons are activated?

A

this releases opoids at the synapse to reduce the chance of any depolarisation at the synapse to reduce the C fibre input

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11
Q

Which fibres modulate pain?

A

Descending pain modulating fibres

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12
Q

Where do pain fibres synapse?

A

substantia gelatinosa

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13
Q

What is the main neurotransmitter in the descending inhibitory pathway

A

serotonin and noradrenaline

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14
Q

What are the two important classifications of pain?

A
  1. Nociceptive vs neuropathic

2. acute vs chronic

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15
Q

What is nociceptive pain?

A

Pain due to tissue damage and inflammation

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16
Q

What is neuropathic pain?

A
  • Pain initiated or caused by a primary lesion or dysfunction in the CNS or PNS (damage to nerve fibres)
  • intense continuos pain that can be accompanied with pins and needles, hyperalgesia, numbness, loss of co-ordination
  • often constant, not reduced by rest
  • associated with severe co morbidity and poor quality of life
17
Q

What are some conditions that can cause neuropathic pain?

A
  • post herpetic neuralgia
  • painful diabetic neuropathy
  • trigeminal neuralgia
  • phantom pain
18
Q

What is allodynia?

A

brushing of the skin causes intense pain

19
Q

How do we treat noiceptive pain?

A
  • rest
  • exercise
  • allow repair
  • normal WHO ladder - paracetmol, NSAIDs, weak opioids (usually responds to pain killers)
20
Q

How do we treat neuropathic pain?

A
  • neuropathic pain killers - gabapentin, amitriptyline
  • spinal cord stimulation
  • often doesn’t respond to pain killers
21
Q

What is acute pain?

A
  • associated with trauma or injury
  • usually nociceptive
  • proportional to magnitude of injury
  • evolutionary protective function
  • assists with wound healing
  • resolves with healing
22
Q

What is chronic pain?

A
  • pain that persists past normal duration of tissue healing
  • 3 months but arbitrary
  • may be dissociated from tissue damage
  • no obvious protective function
  • causes distress and suffering
23
Q

Explain the WHO analgesia ladder from bottom to top:

A
  1. Non-opoid
    - paracetmol
    - NSAIDs
  2. Opoid (in increasing severity)
    - tramadol
    - dihydrocodeine
    - codeine
    - fentanyl
    - morphine
24
Q

What type of pain is the WHO analgesia ladder for and why?

A

acute pain

should NOT apply in chronic pain due to the addictive effects of opoids

25
Q

When should opioids not be used?

A

In chronic pain:

  • when the risk of harm from opioids increases with increased dose but there is no increased benefit
  • if a patient is using opioids but is still in pain, the opioids are not effective and should be discontinued
26
Q

How do we measure pain?

A

Pain = noiceptive input + biopsychosocial phenomena

27
Q

What is the VAS scale?

A
  • 0-10 VAS numeric pain distress scale

- ask patients where they are on the scale

28
Q

Why might pain killers not work?

A
  • biopsychosocial factors
  • tolerance
  • misdiagnosis
  • incorrect dose
  • aren’t tolerated
  • they aren’t very effective
29
Q

What are the four dimensions of pain conceptualized by Loeser?

A
  1. Nociception
  2. Pain
  3. Suffering
  4. Pain behaviours
30
Q

What is lumbar radiofrequency?

A
  • burning nerves at joints

- to reduce back pain

31
Q

What is spinal cord stimulation?

A
  • reduces nerve pain by stimulating dorsal columns
  • involves the delivery of energy to the spinal cord through electrodes in the epidural space
  • works by delivering small electrical pulses to the pain sensing pathways of the spinal cord, effectively altering the pain signals travelling to the brain
32
Q

What is the celiac plexus block most commonly used for?

A

pancreatic carcinoma and upper abdominal neoplasia