Pain Flashcards
What is pain?
Pain – the sensory and emotional experience of
discomfort, which is usually associated with actual or
threatened tissue damage or irritation.
Plays an important protective feedback function
Most common medical complaint
More than 80% of all visits to physicians
Qualities of pain
Sharp Dull Burning Cramping Itching Aching Shooting Throbbing
Organic vs. psychogenic pain
Organic pain – discomfort from tissue damage (e.g.,
stubbed toe, scraped knee)
Psychogenic pain – discomfort without clear organic
basis (e.g., pain disorder – a somatoform disorder)
In the past:
Physicians and researchers thought organic and
psychogenic pain were completely separate.
Today:
Physicians acknowledge that both physical and
psychological factors influence the pain experience.
Acute vs. chronic pain
Acute pain – temporary, lasts less than 6 months
Typically has a definable cause; treated with painkillers
Associated with an increase in anxiety levels
Chronic pain – lasts longer than 6 months
E.g. from rheumatoid arthritis
Associated with high anxiety levels, hopelessness,
helplessness
Influences other behaviours – e.g., sleep
sleep deprivation then increases sensitivity to pain
Types of chronic pain: Part 1
Chronic recurrent pain: Stems from benign causes Repeated episodes of pain and episodes of no pain e.g., myofascial pain syndrome Chronic intractable benign pain: Discomfort that is present all the time Not related to a malignant condition E.g., chronic back pain
Types of chronic pain: Part 2
Chronic progressive pain: Continuous discomfort Associated with a malignant condition Increases in intensity as condition worsens e.g., rheumatoid arthritis, cancer
Types of pain
Referred pain: Pain originating from internal organs perceived as coming from other parts of the body E.g. heart attack Internal organs and skin use same pathway in the spinal cord Due to not being used to pain originating from internal organs
Pain signals
Nociceptors – nerve endings that respond to pain
stimuli and signal injury to the brain
Found in: skin, blood vessels, muscles, joints, etc.
Types of Afferent Peripheral Fibres:
A-delta fibres – coated with myelin, quick
transmission
C fibres – slower impulse – dull, burning, aching
pain
Pain without detectable damage
Neuralgia
Recurrent shooting/stabbing pain along course of nerve
Causalgia
Renamed “Complex regional pain syndrome”
Severe burning pain triggered by minor stimuli (e.g., clothing, puff of air), can occur spontaneously
Sometimes where body has healed – e.g., gunshot, stabbing
Fibromyalgia
Chronic widespread pain with unknown (probably multiple) causes
Phantom Limb Pain
Pain in limb no longer there
Can persist for months and even years
Theories of pain
Early theories of pain:
Specificity theory:
Pain receptors, nerves, brain region; direct and
automatic link between cause of pain and brain
Pattern theory:
Similar; level of pain determined by nerve
impulses from damaged tissue
Commonalities of these theories:
Pain caused by damaged tissue
Psychological consequences only
Pain as an automatic response with a single cause
Psychogenic pain acknowledged but only when no
organic cause can be found
Problems with early theories of pain
Medical treatments (drugs and surgery) tend to work
for acute pain only.
Degree of tissue damage and reports of painful
sensations differ (e.g. soldiers requesting less pain
relief than civilians).
Phantom limb phenomenon; pain felt as coming from
the place where the amputated limb used to be.
Gate-Control Theory of Pain: Part 1
Developed in 1960s by Melzack and Wall
Integrated physiology with psychology and improved
preceding theories; complex pathway mediated by a
network of interacting processes.
The Basics of Gate-Control Theory of Pain
There is a “gating mechanism” located in the spinal cord
(substantia gelatinosa of the dorsal horn)
Gate-Control Theory of Pain: Part 2
Travelling through the gate:
1. Signals of noxious stimulation from nerve fibres at
injury site enter gating mechanism.
2. Brain also sends information about the
psychological state of the individual (e.g. attention,
anxiety, memory of previous experience).
3. If signals pass through gating mechanism, they
activate transmission cells.
4. Transmission cells send impulse to the brain.
Gate-Control Theory of Pain: Part 3
How the gate works
KEY in this theory: gate can be opened or closed
If open: transmission cells send impulses freely
Gates closed/partially closed: output of transmission cells is
inhibited.
Gate-Control Theory of Pain: Part 4
What Controls Opening and Closing of the Gate?
(1) The amount of activity in the pain fibres
Activity of the large fibres due to injury
The stronger the noxious stimulation – the more active the pain fibres
(2) The amount of activity in other peripheral fibres
A-beta fibres – carry information about harmless
stimulation – touching, rubbing, light scratching
Stimulation of the small fibres (e.g. gentle massage, TENS,
medication) tends to close the gate (inhibits pain neurons)
Gating example – TENS machine
TENS = Transcutaneous Electrical Nerve Stimulation
Used for surgery, trauma, long-term pain, or child birth
How it works:
The nerve cannot carry pain impulse and non-pain impulse (from TENS) simultaneously –therefore pain signal is overridden
Also encourages body to produce endorphins
Gate-Control Theory of Pain: Part 5
What Controls Opening and Closing of the Gate?
(3) Messages that descend from the brain
Efferent pathways (brain to spinal cord) can open or close the gate
E.g., emotional factors such as anxiety (open gate) or excitement (close)
Behavioural factors, such as focusing on pain (open) or concentration on other things or distraction (close)
This pathway explains why people who are distracted by environmental stimuli may not notice the pain.
Problems with Gate-Control Theory
No clear evidence yet for precise location of the
supposed “gate”.
Unclear how exactly the psychological factors
interact with the organic basis of pain.
Inhibition of pain
Stimulation-produced analgesia (SPA)
Stimulation to the periaqueductal gray
area of the midbrain produces an
insensitivity to pain (e.g. TENS,
acupuncture); Kotzé & Simpson (2008)
Serotonin activates inhibitory interneurons
release endorphins at pain fibres
endorphins inhibit release of substance P (pain message) from pain fibres
Pain and the role of learning
Classical conditioning: past experience and association can exacerbate pain (e.g., going to the dentist after a bad experience)
Jamner & Tursky (1987): migraine sufferers react with more anxiety to words associated with migraine
Operant conditioning: Reinforcement can exacerbate pain (e.g., getting attention)
Pain and the role of affect
Anxiety
Anxiety and worry make pain worse; problem with
chronic pain, which is harder to treat
High trait anxiety predicts pain experience
Fear
Fear and fear avoidance beliefs (e.g., “It will hurt if I
walk”) can exacerbate pain and predict transition from
acute to chronic pain
Fear of pain might lead to hyper-vigilance of pain and
thus more intense experience of it.
Treatment could work on reducing these avoidance
behaviours.
Cognitions in pain
Catastrophising
Rumination (“I can feel my knee click”); focus on threatening information
Magnification (“I will become paralysed”); overestimation of threat
Helplessness (“Nobody can help me and I just can’t bear the pain anymore”); underestimating personal resources to cope
Each predict pain intensity
Meaning
Positive meaning (e.g., childbirth, muscle strength training) may reduce pain
Negative meaning (e.g., serious illness) may increase pain
Cognitions and behaviour in pain
Self-efficacy
Past positive experiences may improve pain
Locus of control
Attention
Attention to pain increases pain
Distraction decreases pain
Additionally, pain demands attention leaving less attention to other tasks
Assessing pain: Part 1
Interviews:
History of the pain, emotional adjustment, lifestyle factors,
impact on interpersonal relations and work
Pain Questionnaires (e.g. McGill Pain Questionnaire)
Verbal description of pain
Pain Rating Scales
Box Scale (0 = no pain, 10 = worst possible pain)
Visual Analogue Scale:
Assessing pain: Part 2
Observational assessment
Generally considered unreliable, but sometimes required
E.g. children, non-verbal adults, some terminally ill adults
Physiological measures
Assessment of inflammation
Measure of sweating, heart rate, skin temperature
Also often not reliable
Managing pain
Clinical pain – any pain that requires professional
care
Acute
>. Why is this pain important to manage?
- Occurs during surgical procedures
- Following surgical procedures
- Impacts patient adherence to treatment (e.g., returning to the dentist for another filling)
Chronic
>. Why is this type of pain important to manage?
- Important in chronic illness – e.g., arthritis, cancer
- Needs to be managed properly in terminal cases
- Important to the improvement of quality of life
Acute clinical pain
E.g., pain following abdominal
surgery
Many patients experience greater-than-necessary pain following surgery
Can lead to:
Increased infection, slow wound healing (pain and related stress impairs immune and endocrine functioning)
Medical complications and potentially death
Chronic clinical pain
e.g., lower back pain, arthritis, cancer
Can lead to increased hopelessness and despair in the transition from acute chronic pain
While some studies found a relationship between the neurotic triad of personality of the MMPI (hypochondriasis, depression, hysteria) and chronic pain (Armentrout et al., 1982; McGill et al., 1983), others found that the MMPI is not a reliable tool to predict pain perception (Cox et al., 1978; Naliboff et al., 1982)
Other major issues with chronic clinical pain:
Interpersonal and emotional difficulties
Excessive drug use
Frequent sleep disturbance
Medical treatment for pain
Surgical methods
More likely to be effective for
acute pain
Other methods:
Synovectomy – removing membranes of arthritic joints
Spinal fusion – fusing vertebrae to treat severe back pain;
typically using donor bone material to join vertebrae
Behavioural and cognitive treatment: Part 1
Goals: help patients cope more effectively, and reduce
their reliance on drugs; moving client out of comfort
zone back into activities that they had been avoiding.
Operant Approach
Especially used with children
Reinforcement of desirable behaviour (e.g., if you do this
exercise, then we can play a game)
Give praise for desirable activities – sleeping through
naptime, not complaining
Behavioural and cognitive treatment: Part 2
Relaxation and Biofeedback
Helps reduce stress (which is linked to chronic
pain, tension headaches, etc)
E.g., progressive muscle relaxation
E.g., biofeedback – learning control over bodily
functions such as heart rate (through electronic
devices)
Cognitive treatment of pain: Part 1
(1) Distraction
Focusing on a nonpainful stimulus in the immediate environment
Factors:
Attention – greater attention, lower pain ratings
Whether the distractor is interesting
– e.g., watching a movie, being asked to reflect on what’s going on in the movie (used when giving needles to children)
Cognitive treatment of pain: Part 2
(2) Imagery
Guided imagery –alleviation through imaging
mental scene unrelated to the pain
Useful in acute pain
Not clear in terms of its use in chronic pain
Difficult for some people
Cognitive treatment of pain: Part 3
(3) Pain redefinition:
Replacing maladaptive thoughts about threat and harm with constructive and realistic thoughts
Focus often on the internal dialogue
Coping statements: emphasise person’s ability to tolerate
discomfort (e.g., “It hurts, but you’re in control”)
Reinterpretative statements: designed to negate the
unpleasant aspects of discomfort (e.g., “It’s not the worst
thing that could happen”)
Useful for those undergoing medical procedures
But be careful not to create feelings of guilt
Cognitive treatment of pain: Part 4
Pain Redefinition (continued)
1. Medical procedure information – can be provided
by a therapist reduces anxiety and discomfort
2. Coping with chronic pain – therapist can promote
active coping and pain acceptance
Have them perform activities to see they have enjoyment
even with pain present
3. Reducing illogical thoughts in chronic pain patients
Helping to reduce overall discomfort
Effectiveness of MBSR
Pearlman et al. (2010) exposed novice and experienced meditators to painful thermal stimuli and asked them to engage in focused attention in one
condition and open monitoring in another.
During the open m. condition, experienced meditators reported the same intensity of pain, but much less unpleasantness.
Another study found lower pain sensitivity in experienced meditators compared to controls, as well as changes in cortical structure (Grant et al., 2009).
Zeidan et al. (2009) gave people 1-hour mindfulness training for 3 days and then gave painful electrical stimulation. Mindfulness training reduced pain ratings and anxiety. Mathematics distraction had some effect on mild pain, but relaxation did not work.
