Pain Mechanisms

Question 1

Pain - Definition

Answer 1

Unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.
Personal experience influenced by bio-psycho-social factors.

Question 2

Mature Organism Model

Answer 2

Pain experience: affected thoughts, altered emotions.
Gives value to the experience.
Changes the output.
Changes in behavior (adaptive/maladaptive).

Question 3

Neurosignature/Neurotags

Answer 3

Neural network that evokes a specific output.
Work in collaboration or competition.
Strength influenced by size and synaptic efficiency.

Question 4

Action vs Modulation Neurotags

Answer 4

Action: Influence beyond the brain.
Modulation: Influence within the brain.

Question 5

Adaptive Behavior - Characteristics (4)

Answer 5

Response to tissue injury.
Useful to promote healing.
Proportionate to stimulus.
Creates environment for healing.

Question 6

Maladaptive Behavior - Characteristics (4)

Answer 6

Minimal or no pathology.
Does not promote healing.
Disproportionate.
No biological purpose.
(yellow flags))

Question 7

Cognitive Dimensions of Pain (4)

Answer 7

Cultural background
Previous pain experience
Beliefs
Associations

Question 8

Affective Dimensions of Pain (4)

Answer 8

Emotional context at the time of injury.
Catastrophizing
Anxiety
Social support

Question 9

Nociceptive Pain - Definition

Answer 9

Pain that arises from actual or threatened damage to non-neural tissue and is due to activation of nociceptors.

Question 10

Nociceptors (5)

Answer 10

Free nerve endings.
Sensory receptors: mechanical, temperature, chemical and polymodal.

Question 11

Phases of Nociception (4)

Answer 11

Transduction
Transmission
Modulation
Perception

Question 12

Phases of Nociception - Transduction

Answer 12

Noxious stimuli is converted to electrical impulse.

Question 13

Phases of Nociception - Transmission

Answer 13

A-delta and C nervous fibers transmit electrical impulse from noxious stimuli. Peripheral, synaptic and central transmission.

Question 14

What kind of pain do A-delta and C- Fibers conduct?

Answer 14

A-delta: conducts fast pain, acute, specific.
C-fibers: conduct slow pain, dull, diffused.

Question 15

Phases of Nociception - Modulation

Answer 15

Modulation of signals by afferent and efferent pathways in spinal cord.

Question 16

Phases of Nociception - Perception

Answer 16

Noxious event is consciously recognized as pain.
Processing: PAG-THA-INS-aCC-M1,S1-PFC. Brain stem and AM.

Question 17

Pain Modulation System

Answer 17

Periaqueductal Gray (PAG) - Rostral Ventromedial Medulla (RVM).
Can both inhibit and enhance nociception under different conditions.

Question 18

Neuropathic Pain - Definition, Peripheral - Central

Answer 18

Pain caused by a lesion or disease of the somatosensory nervous system. Peripherally generated: trauma, entrapment, spinal root nerve.
Centrally generated: stroke, MS, spinal cord injury.

Question 19

Neuropathic Mechanisms (3)

Answer 19

Ectopic impulses: nerve generates impulse on its own.
Neuroma: fine nerve sprouts.
Crosstalk: nerve activating proximal nerve.

Question 20

Neuropathic Pain - Consequences (2)

Answer 20

Allodynia: non-noxious stimuli becomes noxious.
Hyperalgesia: increased pain from a noxious stimuli.

Question 21

Nociplastic Pain - Definition

Answer 21

Arises from altered nociception despite no clear evidence of actual or threatened tissue damage or disease or lesion of somatosensory nervous system.

Question 22

Nociplastic Mechanism

Answer 22

Lowered threshold becomes chronic due to neuroplasticity. Super-highway for painful stimuli.
Long-term potentiation -> central sensitization.

Question 23

Nociplastic Pain - Consequences

Answer 23

Excessive activation of afferent pathways.
Changes in inhibitory descending pathways: impaired pain inhibition.

Question 24

How is CNS sensitivity maintained? (3)

Answer 24

Ongoing output.
Psychometric factors.
neuroplasticity of CNS.