Physiology and Pathophysiology of Pain Flashcards Preview

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Flashcards in Physiology and Pathophysiology of Pain Deck (39):
1

what is the 1st step of processing pain?

Periphery:
Detection
Transmission to spinal cord (first order neurons)

2

what is the 2nd step of processing pain?

Spinal cord:
Processing
Transmission to brain (Thalamus) (second order neurons)

3

what is the 3rd step of processing pain?

Brain:
Perception, learning, response

4

what is the 4th step of processing pain?

Modulation:
Descending tracts

5

What is nociception?

The detection of tissue damage by specialized transducers connected to A-delta and C fibers

6

what are nociceptors?

Free nerve endings of A delta and C-fibres
Respond to thermal, chemical, mechanical noxious stimuli

7

describe Primary afferents?

Cell body in Dorsal root ganglion
First order neurons
Synapse at spinal cord

8

what are the 4 different types of Primary afferents?

Aα fibres
Aβ fibres
Aδ fibers
C fibres

9

what neurones receive the input from Rexed lamina 2 and 5?

Nociceptive specific
Low Threshold Mechanoceptive
Wide Dynamic Range

10

where does the Spinothalamic tract arise in?

Rexed Lamina 2 & 5

11

what is the Spinothalamic tract ?

Major ascending tract for nociception
sending impulses to thalamus

12

what is the second relay station in the brain?

thalamus

13

where does the Lateral Spinothalamic Tract terminate?

Ventroposterior thalamic nuclei

14

The medial thalamic nuclei receives input from where?

ventral spinothalamic tract

15

where does the Ventroposterior thalamic nuclei project to?

somatosensory cortex

16

where does the medial thalamic nuclei project to?

Cortex
Limbic system

17

where does Pain perception occur?

somatosensory cortex

18

what is the primary control center for descending pain modulation?

Periaqeductal grey

19

describe the defending pathways of pain modulation?

from brain to dorsal horn
Usually decreases pain signal
Noradrenergic system

20

what is hyperalgesia?

abnormally heightened sensitivity to pain
happens whenever there is tissue injury and inflammation.

21

what is allodynia?

Decreased threshold for response

22

what is Spontaneous Pain?

Spontaneous activity in nerve fibres

23

what is Central sensitization?

It is the response of second order neurons in the CNS to normal input both noxious & non-noxious

24

what are the three main components of Central sensitization?

wind-up
classical
long-term potentiation

25

what is the main difference between Central sensitization and peripheral sensitization?

central sensitization happens at the level of spinal cord and acts in tandem.

26

what is wind-up Central sensitization?

Involves only activated synapses

Homosynaptic activity dependent progressive increase in response of the neurons

Manifests over the course of stimuli & terminates with stimuli

27

what is Classical Central sensitization?

Involves opening up of new synapses (silent nociceptors)
Heterosynaptic activity dependent plasticity
Immediate onset with appropriate stimuli
Outlast the initial stimuli duration
Can be maintained even at low levels of ongoing stimuli

28

what is Long-term potentiation

Involves mainly the activated synapses
Occurs primarily for very intense stimuli

29

what is acute pain?

<1 month
Physiological
Presence of noxious stimuli
Serves protective function
Usually nociceptive

30

what is chronic pain?

Pain for 3–6 months or more
Pathological
Presence of noxious
Does not serve any purpose
Nociceptive, neuropathic or mixed

31

What is nociceptive pain?

A sensory experience that occurs when specific peripheral sensory neurones (nociceptors) respond to noxious stimuli

32

What is neuropathic pain?

Pain initiated or caused by a primary lesion or dysfunction in the somato-sensory nervous system

33

describe nociceptive pain

Pain typically localised at the site of injury – often described as throbbing, aching or stiffness
Usually time limited and resolves when damaged tissue heals
Can be chronic
Tends to respond to analgesics

34

describe neuropathic pain

pain occurs in the neurological territory of the affected structure (nerve, root, spinal cord, brain)
Almost always a chronic condition (e.g. postherpetic neuralgia [PHN], poststroke pain)
Responds poorly to analgesics

35

what are some examples of neuropathic pain?

postherpetic neuralgia [PHN]
poststroke pain

36

what drugs are effective when transduction is affected structure?

NSAIDs
Ice
Rest
LA blocks

37

what drugs are effective when transmission is affected structure?

Nerve blocks
Drugs
Opioids
Anticonvulsants
Surgery
DREZ
Cordotomy

38

what drugs are effective when Perception is affected structure?

Education
Cognitive behavioural therapy
Distraction
Relaxation
Graded motor imagery
Mirror box therapy

39

what drugs are effective when Descending modulation is affected structure?

Placebos
Drugs
Opioids
Antidepressants
Surgery
Spinal cord stimulation