Physiology and Pathophysiology of Pain Flashcards

1
Q

what is the 1st step of processing pain?

A

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

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2
Q

what is the 2nd step of processing pain?

A

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

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3
Q

what is the 3rd step of processing pain?

A

Brain:

Perception, learning, response

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4
Q

what is the 4th step of processing pain?

A

Modulation:

Descending tracts

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5
Q

What is nociception?

A

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

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6
Q

what are nociceptors?

A

Free nerve endings of A delta and C-fibres

Respond to thermal, chemical, mechanical noxious stimuli

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7
Q

describe Primary afferents?

A

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

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8
Q

what are the 4 different types of Primary afferents?

A

Aα fibres
Aβ fibres
Aδ fibers
C fibres

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9
Q

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

A

Nociceptive specific
Low Threshold Mechanoceptive
Wide Dynamic Range

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10
Q

where does the Spinothalamic tract arise in?

A

Rexed Lamina 2 & 5

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11
Q

what is the Spinothalamic tract ?

A

Major ascending tract for nociception

sending impulses to thalamus

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12
Q

what is the second relay station in the brain?

A

thalamus

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13
Q

where does the Lateral Spinothalamic Tract terminate?

A

Ventroposterior thalamic nuclei

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14
Q

The medial thalamic nuclei receives input from where?

A

ventral spinothalamic tract

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15
Q

where does the Ventroposterior thalamic nuclei project to?

A

somatosensory cortex

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16
Q

where does the medial thalamic nuclei project to?

A

Cortex

Limbic system

17
Q

where does Pain perception occur?

A

somatosensory cortex

18
Q

what is the primary control center for descending pain modulation?

A

Periaqeductal grey

19
Q

describe the defending pathways of pain modulation?

A

from brain to dorsal horn
Usually decreases pain signal
Noradrenergic system

20
Q

what is hyperalgesia?

A

abnormally heightened sensitivity to pain

happens whenever there is tissue injury and inflammation.

21
Q

what is allodynia?

A

Decreased threshold for response

22
Q

what is Spontaneous Pain?

A

Spontaneous activity in nerve fibres

23
Q

what is Central sensitization?

A

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

24
Q

what are the three main components of Central sensitization?

A

wind-up
classical
long-term potentiation

25
Q

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

A

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

26
Q

what is wind-up Central sensitization?

A

Involves only activated synapses

Homosynaptic activity dependent progressive increase in response of the neurons

Manifests over the course of stimuli & terminates with stimuli

27
Q

what is Classical Central sensitization?

A

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
Q

what is Long-term potentiation

A

Involves mainly the activated synapses

Occurs primarily for very intense stimuli

29
Q

what is acute pain?

A
<1 month
Physiological
Presence of noxious stimuli
Serves protective function
Usually nociceptive
30
Q

what is chronic pain?

A
Pain for 3–6 months or more
Pathological
Presence of noxious 
Does not serve any purpose
Nociceptive, neuropathic or mixed
31
Q

What is nociceptive pain?

A

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

32
Q

What is neuropathic pain?

A

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

33
Q

describe nociceptive pain

A

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
Q

describe neuropathic pain

A

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
Q

what are some examples of neuropathic pain?

A

postherpetic neuralgia [PHN]

poststroke pain

36
Q

what drugs are effective when transduction is affected structure?

A

NSAIDs
Ice
Rest
LA blocks

37
Q

what drugs are effective when transmission is affected structure?

A
Nerve blocks
Drugs
    Opioids
    Anticonvulsants
Surgery
    DREZ
    Cordotomy
38
Q

what drugs are effective when Perception is affected structure?

A
Education
Cognitive behavioural therapy
Distraction
Relaxation
Graded motor imagery
Mirror box therapy
39
Q

what drugs are effective when Descending modulation is affected structure?

A
Placebos
Drugs
    Opioids
    Antidepressants
Surgery
    Spinal cord stimulation