1
Q
Pain classification systems
A
- Temporal
- Mechanism
- Diagnosis
- Body site/organ system
- Etiology
2
Q
Temporal classification system
A
- acute vs chronic
3
Q
Temporal classification system: acute
A
- pain that lasts <3 months
4
Q
Temporal classification system: chronic
A
- pain that lasts >3months
5
Q
Physiological mechanism classification system
A
- Nociceptive pain
- Neuropathic pain
- Nociplastic pain
6
Q
Physiological mechanism classification system: nociceptive pain
A
- pain that arises from damage or disease of non-neural tissue
*pain is a symptom
7
Q
Physiological mechanism classification system: neuropathic pain
A
- pain that arises from damage or disease of the somatosensory nervous system
- pain is a symptom
8
Q
Physiological mechanism classification system: nociplastic pain
A
- pain that arises from dysfunction of the somatosensory nervous system
- pain is a disease
9
Q
Diagnosis classification system
A
- Chronic primary pain
- Chronic secondary pain
10
Q
Diagnosis: chronic primary pain
A
- 1 or more anatomical region
- greater than 3 month duration
- associated with sig emotional distress
- pain is a disease, not secondary to tissue damage/disease
11
Q
Diagnosis: chronic secondary pain
A
- pain is a symptom, secondary to tissue damage/disease
- chronic pain is a co-diagnosis of the underlying disease when pain becomes a problem in its own right
12
Q
Body site/organ system classification
A
- visceral pain
- pelvic pain
- neck pain
- low back pain
13
Q
Etiology classification system
A
- post-traumatic
- post- surgical
- idiopathic
- disease (cancer, MS)
- genetic disease
14
Q
Are these classification systems mutually exclusive?
A
NO
15
Q
Examples of why these classification systems are not mutually exclusive
A
- chronic primary diagnoses predominantly have nociplastic pain mechanisms
- chronic neuropathic pain is a diagnosis, but also describes the temporal nature and mechanism
- initial onset of acute pain is often nociceptive (not always)
- chronic pain (esp>year) will almost always have a component of nociplastic pain mechanisms
16
Q
Where is SOAP notes does a multi-dimensional pain classification go?
A
- analysis
17
Q
How are nociception and pain different phenomena?
A
- NOT ALL nociception results in pain and NOT ALL pain is a result of nociception
- BUT pain is often a result of nociception (nociceptive pain)
18
Q
Which nervous sytem is involved in nociception?
A
- somatosensory (central and peripheral NS)
19
Q
1st order neuron
A
- primary afferent
- peripheral to dorsal horn of spinal cord
20
Q
2nd order neuron
A
- from spinal cord to thalamus
21
Q
3rd order neuron
A
- thalamus to various brain regions
22
Q
Anatomy of a nerve
A
- many neurons (motor and sensory)
- nerve fibre: axon of a single neuron
23
Q
Neuron
A
- cells in the nervous system that receive sensory input from the external world or send motor commands to our muscles
24
Q
What are nociceptive neuron and what type of neuron?
A
- neuron of somatosensory nervous system that is capable of encoding noxious stimuli
- psuedounipolar neurons
25
Nociceptor
- a threshold sensory receptor that is capable of transducing and encoding noxious stimuli
26
Noxious stimuli
- an actually or potentially tissue-damaging event transduced and encoded by nociceptors
27
Type of noxious stimuli
- thermal (extreme hot or cold)
- chemical (poison, infection)
- mechanical (laceration, pressure
28
What is unique about nociceptors?
- free nerve endings
- respond to multiple types of stimuli
29
Types of fibres of nociceptive neurons
1. A-delta
2. A-beta
3. C
30
Myelination of the diff fibre types of NNs
- Abeta/Adelta = myelinated: relatively fast velocity (immediate, sharp pain)
- C-fibres = unmyelinated: relatively low velocity (lingering, achy pain)
31
Stages of nociception
1. Transduction
2. Transmission
3. Perception
4. Modulation
32
What is transduction?
- noxious stimuli activate nociceptors that send nociceptive signals to the spinal cord
33
Physiological steps of transduction
1. noxious stimulus activates nociceptor
2. ion channels open
3. ions enter and depolarize neuron
4. action potential is generated (if depolarization reaches threshold)
34
What stimulus is required to activate an action potential is transduction?
- the noxious stimulus must be relatively high to stimulate that danger is occuring
35
What is transmission?
- nociceptive signals enter the dorsal horn of the spinal cord and the signal is transmitted up to the brain
- signal may be modulated (step 4) before transmission to the brain
36
Which order neurons are involved in the transmission stage?
- 2nd and 3rd order neurons
37
What is perception?
- nociceptive signals enter the brain along with other info (sensory, cognitive, affective) and brain determines whether or not to produce pain
38
Components of the body-self neuromatrix
1. cognitive
2. affective
3. sensory
39
Inputs to body-self neuromatrix
1. cognitive related brain areas (thoughts)
2. sensory signalling systems (sensory input)
3. emotion-related brain areas (feelings)
40
Neuromatrix theory: Outputs to brain areas
1. Pain perception
2. Action programs
3. Stress-regulation programs
41
What is modulation?
- feedback loop
- brains sends descending signals to the spinal cord to modulate ascending nociceptive signals
- can be excitatory (amplify pain) or inhibitory (reduce pain)
42
How does modulation work?
- neurons in midbrain and brainstem have opioid receptors
- activation of these receptors triggers release of inhibitory neurotransmitters
43
What are the inhibitory neurotransmitters that can be involved in modulation?
- seratonin
- noradrenaline
- GABA
44
How do pain treatments work to dampen pain?
- activating descending inhibition
45
Conditioned pain modulation (clinical example)
- also called diffuse noxious inhibitory control
- when a noxious stimulus applied outside of the pain location (ie. shoulder) activates descending inhibition and provides diffuse pain relief at pain site (ie. hand)
46
What is a receptor field of NNS?
- portion of sensory space where stimulation will activate the neuron
47
Clinical significance of receptor fields
- smaller fields = denser innervation = larger representation in sensory cortex = high acuit/precision when perceiving sensation
- ex. fingertips
48
Small receptor fields
- high precision in skin
- less precise in muscle/joint
49
Large receptor fields
- poor precision in viscera
50
Localization of nociceptive pain
- nociceptive pain is highly localized to area of tissue damage compared to other pain mechanisms
51
Referred pain
- receptor fields from multiple NNs located in viscera and elsewhere converge onto a common second order neuron
52
Do all nociceptors respond to all stimuli?
NO
53
What noxious stimuli do nociceptors located in the muscle respond to?
- mechanical
- chemical
54
What noxious stimuli do nociceptors located in the joint respond to?
- mechanical
55
What noxious stimuli do nociceptors located in the viscera respond to?
- mechanical
- thermal
- chemical
56
What noxious stimuli do nociceptors located in the skin respond to?
- mechanical
- thermal
- chemical
57
Key messages
- presence of noxious stimuli almost always results in nociception
- nociception usually results in pain but not always
- you can have nociception without pain
- can have pain without tissue damage/nociception
PT1 Pain science
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