Week 10- Pain

Question 1

Defining Pain

Answer 1

• Pain is: “An unpleasant sensory and emotional experience
  associated with actual or potential tissue damage, or described in
  terms of such damage.” International Association for the Study of

-“Pain is a complex sensory and emotional experience that is
heavily influenced by prior experience and expectations of pain”

Question 2

Types of pain (acute versus chronic)

Answer 2

-Acute pain – pain that has rapid onset and goes away quickly;
temporary; associated with increased heart-rate and blood
pressure (SAM activation).

-Chronic pain – pain that lasts longer than 6 months; persistent
beyond normal tissue healing time; often can predict onset of
depression (HPA activation).

Question 3

Types of pain (nociceptive versus neuropathic)

Answer 3

-Nociceptive pain – pain from injury or damage to the body
(burns, cuts, breakage, etc.); most common form of pain; due
to activation of “nociceptors” (specialised peripheral pain
receptors or nerve cells that initiate the pain sequence, akin to
an alarm signal). [from “Nocēre” to harm, hurt, in Latin]

-Neuropathic pain – malfunctioning nerves send pain signals
(no obvious cause of trauma or injury) or due to misfiring of
somatosensory system in brain. Most extreme form = phantom
limb syndrome.

Question 4

Ways of Measuring Pain (behavioural)

Answer 4

Limping / rigidity
 Guarding / bracing
 Restlessness / rubbing
 Grimacing / tearfulness
 Moaning / sighing

-May be required because the person could be elderly, a child, or they may been in too much pain to respond accurately to questionnaire / verbal report

Question 5

Ways of measuring pain: Self-report via visual analogue scales / visual analogue
thermometer

Answer 5

scale where patients rate there pain e.g. 0=no pain, 100= extreme pain

-There are many different versions of VAS

Question 6

Example of a self report questionnaire to measure pain

Answer 6

The McGill Pain Questionnaire
pain intensity scale, a 5-point ordinal verbal scale (Melzack, 1975)

 Mild
 Discomforting
 Distressing
 Horrible
 Excruciating

Question 7

Ordinal face scales

Answer 7

Another way of measuring pain = basically a visual representation of the pain scale and patients choose where there pain falls along this e.g. o= happy face, and 5= crying face

Could be helpful for kids who may struggle to conceptualise number pain scale?

Question 8

Tracking momentary reports of pain using ecological momentary assessment (EMA)

Answer 8

-Could utilise phones i.e. ask at points throughout the day : How much pain are you experiencing right now?
(0 no pain… 10 worst possible pain)

-Advantage is that it allows researchers/ clinicians to under the pain of individuals as it related to someones normal routine/ as they go about there life so greater ecological validity.

Question 9

Advantage of ecological momentary assessment of pain in terms of experienced versus remembered pain difference?

Answer 9

-Memories for pain can
be biased, particularly when summarizing over longer periods
of time (e.g., pain “over the last week”).

e.g strone & Broderick (2007) study where Remembered pain was higher
in intensity than averaged
momentary pain (experienced
pain)

More broadly speaking this shows how psychological processes (in this case memory) can effect pain experience

Question 10

Why are memories of pain biased

Answer 10

Retrospective summary
reports of pain are influenced by peak-and-end effects and
duration neglect.

Question 11

Peak-and-end effects

Answer 11

the tendency to prioritise high intensity
pain episodes (“peaks”) and more recent pain experiences (“ends”)
in retrospective summary judgments of pain.

Question 12

Duration neglect

Answer 12

– the tendency to ignore pain-free periods of time
in retrospective summary judgments of pain.

Makes sense from an evolutionary perspective -> pay attention to shifts/ changes not long periods of the same

Question 13

Example of peak and end effects: memories of colonoscopies (Redelmeier, Katz & Kahneman)

Answer 13

• Almost 700 people
• Hospital setting
• Randomly assigned to receive normal colonoscopy (conventional group) or modified ending group (tip of the colonoscope was kept in the rectum for a period-> less painful ending)
• Pain rated continually across the course of the 30 minute procedure
• Peak same for modified ending group
• BUT Did the end effect (same as recency effect) result in a difference in overall recall of pain for the procedure?
• YES it did = Those in the modified procedure showed a 10% increase in the return to colonoscopies (because they remembered it as less painful).

-Specifically overall pain was rated as 4.4 for the modified and 4.9 for the conventional with a significant P value of .006

-ALSO… in follow up those in the modified ending group were 10% more likely to go for rectum colonoscopy in the future because experienced it as less painful.

Question 14

How might the peak/ end effect colonoscopy study findings apply to other thing?

Answer 14

• Lollipop at the end of doctors’ appointments
• Better ending in relationship? Remember it as not as bad.
• Memories for vacations and holidays : better to design itinerary to have high peaks and impactful/ strong ending.

-Designing a rollercoaster to have the best memory

Question 15

Ways of Measuring Pain through objective indicators : fMRI

Answer 15

-Not a 1:1 correspondence between pain, brain activation, and subjective experience i.e. same level of activation in the pain matrix can result in different subjective experiences of pain for different things.

• Complex brain network (not a “pain center” in brain)

Question 16

Are objective methods of pain more valid than subjective methods

Answer 16

-No, they are both important in gaining an overall picture of the pain experience.

Question 17

Psychology and Pain

Answer 17

-Pain is not a straightforward process; it
is malleable through psychological
factors.

-There are complex ascending (bottom
up -> from spinal cord to brain) and descending (top down -> from brain to spinal cord) pathways between the spinal cord and the brain, and the complex pathways within the brain. These pathways represent multiple entry points for psychological modulation and, in turn,
individual differences in pain
experiences.

Question 18

Bottom up effects on pain

Answer 18

-Nociceptors at site of injury are activated

-Nerve impulses due to this activation travel along primary afferent neurons (fibers) through the dorsal root ganglion and into the spinal cord at the dorsal root

-Different fibers carry different information e.g.
- non-noxious mechanical stimulus= Abeta fibers
- Noxious mechanical stimulus = a-delta (sharp pain)
-Noxious heat and chemical stimulus = C fibers (dull constant pain)

-Fibers transport signal to the spinal cord and then travel to the brain where we get perception

Question 19

Bottom up effects: gate control theory

Answer 19

-Gate in the brain -> normally gate is open and you would feel the pain.

-There are things that can modulate the gate and effect whether you experience pain

• Stimulating the touch-related Aβ fibres reduces transmission of pain signal by activating the inhibitory neuron (purple) which deactivates the projection neuron (green). This is why mechanically
  activating the skin near an injury (e.g. rubbing, holding) can reduce pain sensations.

Question 20

Top Down Effects on pain

Answer 20

There are also descending analgesic nerves (from brain to spinal cord) with receptors that match:

 Exogenous opiates (opium, codeine, morphine, heroin etc.)
 Endorphins (“nature’s painkiller”)

When opiates or endorphins are ingested or activated,
they inhibit ascending pain signals by closing the gate
from the spinal cord to the brain (by activating the
inhibitory interneuron)

Question 21

Endorphins: what releases them

Answer 21

-Exercise (10 minutes minimum)

-Acute stress

-Childbirth and surgery

-Acupuncture

-Placebo effects

Question 22

Anterior Cingulate Cortex

Answer 22

The ACC is critical brain region involved in the “affective component” of pain
(e.g., how distressed we feel in response to pain; the interpretation of the sensory component of pain). The ACC modulates the limbic system and links to the prefrontal cortex. Interestingly, the ACC also plays an important role in emotional and social processing. Complex pattern of activation.

-Emotional/ effective component of pain is the role of the ACC as such the ACC can be seen as the interface of psychological processes effecting the experience of pain.

Question 23

Link between endogenous opioids and drugs

Answer 23

Endorphins are the body’s natural painkiller; exogenous opiates like
codeine, morphine, and heroin activate on these same pathways.

Question 24

Psychology & Pain Pathways

Answer 24

-Pain pathways are complex; there are multiple entry points for psychological
modulation and, in turn, individual differences in pain experiences.

• Some pathways involve activating endorphins, which reduce pain by activating the descending nerves, which block the gate at the spinal cord. Any factors that affect the anterior cingulate cortex (ACC), can turn up or down our interpretations of pain.
• There are common brain regions between emotional pain and physical pain. Emotional pain, including heightened negative emotion and stress, increases pain evoked activity in the anterior cingulate cortex (ACC) and anterior insula; emotional
  pain activates pain regions.
• There are common brain regions between social pain and physical pain (a “common neural alarm” Anisman, p. 339). Social pain, including isolation and rejection, increases pain-evoked activity in the anterior cingulate cortex; social exclusion activates pain regions similar to physical pain.

Question 25

Psychological Factors
that Increase Pain: Pain catastrophizing

Answer 25

=is the tendency to magnify the threat value of pain stimulus, to
feel helpless in the context of pain, and to have problems inhibiting pain-related thoughts in anticipation of, during, or following a painful encounter

this is linked in with anxiety and neuroticism

-encompasses = magnification, rumination, helplessness

If score on this then pain experience is likely to be worse as it reinforces brain circuits that magnify the actual sensory experience.

Question 26

Psychological Factors
that Increase Pain

Answer 26

-Pain catastrophizing – increases salience of pain

-Negative emotion – increases pain-evoked activity in the ACC; emotional pain activates regions similar to physical pain.

-Isolation and rejection – increases pain-evoked activity in the ACC; social
exclusion activates pain regions similar to physical pain (“common neural
alarm”)

-Greater brain connectivity, and dysfunction of pain inhibitory pathways
increases likelihood of developing a chronic pain condition or “pain
chronification” like fibromyalgia

Question 27

Chronic pain + it’s influences

Answer 27

“Pain that lasts 6 months or longer or longer than necessary for
healing to occur”

Chronic pain susceptibility is influenced by genetics, traumatic births and prematurity, injury, stressful events, and personality
(pessimism, neuroticism, anxiety, catastrophizing).

Question 28

Psychological Factors
that Decrease Pain

Answer 28

Distraction
- Reduces transmission of pain signals ascending from spinal cord (possibly due to endogenous opioids)
-Reduces impact of pain signals in the brain through refocusing attention

Reduction in emotional or social pain (mindfulness decreases activity in the
ACC and insula; control and self-efficacy decreases intensity of appraisal;
social support decreases activity in the ACC)

 Stress-induced analgesia – increases endorphin activity in brain and activates
descending analgesic pathways (acute stress, temporary)

 Psychological treatments reduce the experience of pain (cognitive
behavioural therapy, mindfulness, relaxation training, hypnosis, biofeedback,
distraction, multimodal treatment strategies)

Question 29

Video clip 1

Answer 29

-23 year old Caleb was on a motor bike accident and suffered second and third degree burns

-Armed with the knowledge the pain is experienced in the brain -> researchers are using psychological treatments to counteract pain

-Wherever visual gaze is where attention is. For patients like caleb they look at tools the nurses use to dress wounds/ undergo physiotherapy and these become associated with pain. As such looking at them amplifies the pain experience.

-Physiotherapy = most painful part of rehabilitation so the target of researchers:
-> Give the patient an experience to distract him through VR (snow world)
-This means visual experience isn’t focused on the processes occuring in the hospital room (i.e. attention elsewhere and so less pain).
-With VR saw a 50% reduction in pain related activity in the brain for caleb during physiotherapy
-Caleb brain is not able to process the pain signals he is getting even though he has getting the same amount of input which lessens the pain he feels.

Question 30

Video clip 2

Answer 30

-Rebecca had a stroke

-Since she has had chronic pain of her left side -> feels like there is something stabbing her eye, and huge pressure on the left side of her face even though physical cause has disappeared

-Huge loss of function in everyday life, she speaks of hiding pain from other people so that not to be a burden/ constant downer.

-With chronic pain activity in the pain matrix is constant i.e pain system continues to fire. There are also
Structural and chemical changes that occur in the brain as a result -> e.g. motor cortex

-A way to reverse the changes made in the brain? Transcranial magnetic stimulation = fire electrical impulses into the brain.

-When the researchers fire impulses into the area of the brain that normally moves her hand -> Rebecca’s arm moved instead= this demonstrates the rewiring that has occurred of the motor cortex map.

-With repeated stimulation via transcranial magnetic procedure the hope is to be able to rewire the motor cortex back to its original function so it’s more able to control pain.

-For the first time in 5 years Rebecca feels complete relief from her pain. Unknown whether the effect with be permeant but there is hope .