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Flashcards in Pathophysiology of Pain Deck (44):
1

what is pain?

an unpleasant sensory and emotional experience which we primarily associate with tissue damage or describe in terms of damage.

2

is pain a stimulus?

no

3

describe the pain pathway from the periphery to modulation

> periphery there is detection and transmission to the spinal cord via first order neurons
> spinal cord there is processing and transmission to the brain (thalamus) via second order neurons
> brain there is perception, learning and response
> modulation is the descending tracts

4

what is nociception?

the detection of tissue damage by specialised transducers connected to A-delta and C fibres

5

what are nociceptors?

free nerve ending of A delta and C fibres

6

what do nociceptors respond to?

thermal, chemical, mechanical noxious stimuli

7

where is the first order neurons cell body?

in the dorsal root ganglion

8

describe A alpha and A beta fibres

> myelinated
> large diameter
> proprioception and light touch

9

describe A-delta fibres

> lightly myelinated
> medium diameter
> nociception
> fast/sharp pain

10

describe C fibres

> unmyelinated
> small diameter
> slow conducting
> innocuous temperature, itch, dull pain

11

describe the neurons that will receive the input in the spinal dorsal horn

> nociceptive specific
> low threshold mechanoceptive
> wide dynamic range

12

what does the lateral spinothalamic tract convey?

fast and slow pain (pain and temperature sensations)

13

what does the anterior spinothalamic tract convey?

sensation of simple touch

14

what rexed lamina does the spinothalamic tract arise from?

2 and 5

15

what is the second relay station?

the thalamus

16

what are the connections to the thalamus?

> cortex
> limbic system
> brainstem

17

where does pain perception occur?

in the somatosensory cortex

18

what is hyperalgesia?

increased perception of pain or even the perception of non-noxious stimuli as noxious.

19

when does hyperalgesia occur?

whenever there is a tissue injury and inflammation, it occurs in the surrounding uninjured tissue

20

what is allodynia?

is type of hyperalgesia where there is a decreased threshold for pain

21

describe the changes in nociceptor in allodynia

there is decreased threshold for response

22

describe the changes in nociceptor in hyperalgesia

exaggerated response to normal and supranormal stimuli

23

describe gate control theory

non painful input closes the gate to the painful input, stopping it from travelling to the central nervous system. stimulation of a non-noxious input is able supress pain

24

describe the changes in nociceptors in spontaneous pain

there is spontaneous activity in nerve fibres

25

what is central sensitisation?

the response of second order neurons in the CNS to normal input both noxious and non-noxious

26

name three main components in central sensitisation

> wind up
> classical
> long term potentiation

27

describe wind up central sensitisation

> involves only activated synapses
> homosynaptic activity dependent progressive increase in response of the neurons
> manifests over the course of the stimuli and terminated with the stimuli

28

in classical central sensitisation what is opened up in the dorsal horn?

new synapses, silent nociceptors

29

in classical central sensitisation what is heterosynaptic activity dependent on?

plasticity

30

describe onset of classical central sensitisation

it is immediate with the appropriate stimuli

31

can the classical sensitisation outlast the initial stimuli duration?

yes and it can be maintained at low levels of ongoing stimuli

32

describe long term potentiation

> involves mainly activated synapses
> occurs primarily for very intense stimuli

33

what conditions involves supracentral sensitisation?

> fibromyalgia
> chronic widespread pain
> painful physical symptoms of depression/anxiety

34

describe acute pain

> less than a month
> usually obvious tissue damage
> increased nervous system activity
> resolves on healing
> serves protective function
> usually nociceptive

35

describe chronic pain

> 3-6months or more
> beyond expected period of healing
> no protective function
> degrades health and function
> nociceptive/neuropathic/mixed

36

what is nociceptive pain?

a sensory experience that occurs when specific peripheral sensory neurons respond to noxious stimuli

37

in nociceptive pain is there often specific localisation?

yes, often describes and throbbing, aching, stiffness

38

what is neuropathic pain?

pain initiated or caused by a primary lesion or dysfunction in the somatosensory nervous system

39

describe the painful region in neuropathic pain

it is not necessarily in the same region as the site of injury but occurs in the neurological territory of the affected structure

40

which responds to conventional analgesics better, nociceptive pain or neuropathic pain?

nociceptive pain

41

what works on transduction of pain?

> NSAIDs
> Ice
> Rest
> LA blockers

42

what works on transmission of pain?

> nerve blocks
> drugs (opioids, anticonvulsants)
> surgery (DREZ, cordotomy)

43

what works on the perception of pain?

> education
> congnitive behavioural therapy
> distraction
> relaxation
> graded motor imagery
> mirror box therapy

44

what works on descending modulation?

> placebos
> drugs (opioids, antidepressants)
> surgery (spinal cord stimulation)