Pain Mechanisms Flashcards
Pain - Definition
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.
Mature Organism Model
Pain experience: affected thoughts, altered emotions.
Gives value to the experience.
Changes the output.
Changes in behavior (adaptive/maladaptive).
Neurosignature/Neurotags
Neural network that evokes a specific output.
Work in collaboration or competition.
Strength influenced by size and synaptic efficiency.
Action vs Modulation Neurotags
Action: Influence beyond the brain.
Modulation: Influence within the brain.
Adaptive Behavior - Characteristics (4)
Response to tissue injury.
Useful to promote healing.
Proportionate to stimulus.
Creates environment for healing.
Maladaptive Behavior - Characteristics (4)
Minimal or no pathology.
Does not promote healing.
Disproportionate.
No biological purpose.
(yellow flags))
Cognitive Dimensions of Pain (4)
Cultural background
Previous pain experience
Beliefs
Associations
Affective Dimensions of Pain (4)
Emotional context at the time of injury.
Catastrophizing
Anxiety
Social support
Nociceptive Pain - Definition
Pain that arises from actual or threatened damage to non-neural tissue and is due to activation of nociceptors.
Nociceptors (5)
Free nerve endings.
Sensory receptors: mechanical, temperature, chemical and polymodal.
Phases of Nociception (4)
Transduction
Transmission
Modulation
Perception
Phases of Nociception - Transduction
Noxious stimuli is converted to electrical impulse.
Phases of Nociception - Transmission
A-delta and C nervous fibers transmit electrical impulse from noxious stimuli. Peripheral, synaptic and central transmission.
What kind of pain do A-delta and C- Fibers conduct?
A-delta: conducts fast pain, acute, specific.
C-fibers: conduct slow pain, dull, diffused.
Phases of Nociception - Modulation
Modulation of signals by afferent and efferent pathways in spinal cord.
Phases of Nociception - Perception
Noxious event is consciously recognized as pain.
Processing: PAG-THA-INS-aCC-M1,S1-PFC. Brain stem and AM.
Pain Modulation System
Periaqueductal Gray (PAG) - Rostral Ventromedial Medulla (RVM).
Can both inhibit and enhance nociception under different conditions.
Neuropathic Pain - Definition, Peripheral - Central
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.
Neuropathic Mechanisms (3)
Ectopic impulses: nerve generates impulse on its own.
Neuroma: fine nerve sprouts.
Crosstalk: nerve activating proximal nerve.
Neuropathic Pain - Consequences (2)
Allodynia: non-noxious stimuli becomes noxious.
Hyperalgesia: increased pain from a noxious stimuli.
Nociplastic Pain - Definition
Arises from altered nociception despite no clear evidence of actual or threatened tissue damage or disease or lesion of somatosensory nervous system.
Nociplastic Mechanism
Lowered threshold becomes chronic due to neuroplasticity. Super-highway for painful stimuli.
Long-term potentiation -> central sensitization.
Nociplastic Pain - Consequences
Excessive activation of afferent pathways.
Changes in inhibitory descending pathways: impaired pain inhibition.
How is CNS sensitivity maintained? (3)
Ongoing output.
Psychometric factors.
neuroplasticity of CNS.
