Introduction to Pain Flashcards
Definition of pain
Unpleasant sensory, emotional experience linked with actual/potential tissue damage or described in terms of such damage
Definition of placebo effect
Patient believes in an effective treatment and expects a reduction in symptoms
Definition of hidden treatment
Drug administered by a computer
Definition of active treatment
Drug administered visibly by a healthcare professional
Definition of nociceptive pain
Pain that arises due to physical damage
Definition of inflammatory pain
Pain experienced in an immune response
Definition of neuropathic pain
Caused by damage to somatosensory system
Definition of dysfunctional pain
Chronic pain
Definition of allodynia
Pain threshold lowered so stimuli that don’t normally cause pain do
Definition of hyperalgesia
Increased responsiveness => exaggerated/prolonged pain
Describe the incorrect specificity theory
Intensity of pain directly related to amount of associated tissue injury
What is pain
Unpleasant sensory and emotional experience associated with actual/potential tissue damage or or described in terms of such damage
Describe the role of nociceptors in pain sensation
Noxious stimuli detected by nociceptor receptors
Electrical energy only generated if threshold exceeded
Larger the change in voltage => increased frequency of AP generated
Describe the ascending pathway of pain
-which pathway is involved
Spinothalamic, spinoreticular
Peripheral nociceptors send impulse down sensory afferent
Synapse with 2nd order neurone in dorsal horn
Decussation from dorsal horn=>ventral contralateral horn. Ascends up spinothalamic/spinoreticular
Synapses with 3rd order neurone in thalamus => cerebral cortex
What type of pain is associated with each pain ascending pathway
Spinothalamic
-discriminative fast pain
Spinoreticular
-arousal and unpleasant dull pain
How is pain processed in the spinal cord
Different sensory afferents terminate in different regions of the DH
Pain in regions I and II
Describe the incorrect pain matrix theory and processing in the brain
Areas in the brain responsible for processing nociceptive inputs and generating pain sensation
What are the 3 main opioids released in the brain
What are the receptors for these opioids
Specific opiate receptor (u, s, k) in brain tissue
- endorphins
- dynorphins
- enkaphalins
Describe the descending pain modulatory system
Periaqueductal gray in midbrain produces analgesia when electrically stimulated
Fibres descend from PAG =>on seretonergic neurones in RVM medulla
RVM => inhibition/facilitation of nociceptive processing
What are the 3 weaknesses of specificity
Does not account for pain without damage
Does not account for damage without pain
Psychological factors not considered
Describe the Gate Control Theory of Pain
When inhibitory neurone activated by more sensory pain signal => pain signal not sent to transmission cell => brain
When inhibitory neurone inhibited by more pain => pain signal sent to transmission cell => brain
What 2 fibres are involved in
- pain
- somatosensation
Pain
- Ad
- C
Somatosensation
- Aa
- Ab
What 3 factors regulate the gate
Activity in pain fibres
Activity in other peripheral fibres
Descending pathways, psychology and attention to pain
What are the 3 components of pain
Describe them
Sensory discrimination
-sense of intensity, location and duration
Affective motivational
-unpleasant and desire to escape it
Cognitive component
-involving judgements, beliefs, memories, perception of environment
How would you treat pain
-4 methods
Combination of treatments
- physical therapy
- psychological approaches (CBT)
- relaxation, hypnosis
- placebo
What is the placebo effect
Psychosociobiological phenomenon, patient believes in an effective treatment => expects reduction in symptoms
What are the 2 possible mechanisms of placebo action
- psychosocial
- biochemical
Psychosocial
- conscious cognitions of belief and improvement (verbal suggestions can be enough)
- unconscious conditioning with drug
Biochemical
-cascade of biochemical events in the brain following administration
Describe the open and hidden effect in treatment
What were the effects of both treatments
Hidden treatment
- drug administered by computer
- smaller reduction in pain (actual effect)
Open treatment
- drug administered visibly by doctor
- greater reduction in pain (actual+placebo effect)
What are the 2 types of adaptive and maladaptive pai
Adaptive
- Nociceptive
- Inflammatory
Maladaptive
- Neuropathic
- Dysfunctional
Why do we need to be sensitive to pain
What is the problem with being hypersensitive
Sensitivity allows us to detect potentially harmful stimuli
Hypersensitivity => pain that provides no benefit
What are the effects of both types of pain hypersensitivity
- allodynia
- hyperalgesia
Allodynia
-threshold lowered so stimuli that normally don’t cause pain do
Hyperalgesia
-increased responsiveness => exaggerated/prolonged pain
Describe the 2 mechanisms in pain hypersensitivity
- peripheral sensitisation
- central sensitisation
Peripheral sensitisation
- decreased threshold, increased responsiveness of peripheral nociceptors
- as a result of inflammatory chemicals (prostaglandins)
Central sensitisation
- increased neurone excitability in CNS
- triggered by an activity burst in nociceptors => alters synaptic connection strength in SC
What are the 2 subtypes of pain
- duration
- conduction speed
- treatment
Acute/nociceptive
- strong noxious stimulus activates nociceptors
- short duration
- fast nerve conduction
- analgesia
Chronic
- pain that lasts past normal healing time (3-6+months)
- slow nerve conduction
- more behavioural than drug treatments
Describe the effects of catastrophizing pain
Adding more negative emotions to pain signals
=> pain is harder to control, less likely to recover as fast
What are the psychological trains of thought that are needed for pain relief
Perceiving evaluation as complete
Feeling the received explanation for treatment
Believing that treatment improved daily activity
