Lecture 4: Pain Measurement in Humans and Animals Flashcards
What would be a subjective definition of physical tiredness?
-feeling of tiredness with a physical appearance (eg. heavy and tense feeling in the body, mild pain)
What would be an objective definition of physical tiredness?
-any practice induced reduction in the ability to exert muscle power of force. (impairment of muscle fibers, decline in motoneuron input
What would be a subjective definition of mental tiredness?
-feeling of tiredness with a mental flavour (mild sadness, cannot think straight, relaxed in a pleasant way, tensed and irritable, heavy feeling in the head)
What would be an objective definition of mental tiredness?
-any practice induced reduction in the ability to perform mental work. (inability to concentrate, slowness in thinking, learning and memory difficulties, lack of creative force in thinking)
What is a thermode?
- machine that can heat up or cool down
- the temperature can hold for a few seconds
- apply it usually on the volar forearm.
- they measure ether pain threshold or pain tolerance
What is a pain threshold?
-at what point does the stimulus become painful (it’s starting off at belong painful)
What is pain tolerance?
How much pain you’re willing to accept.
What were the findings of the study where they compared pain threshold and pain tolerance for people with normal blood pressure and people with hypotension?
- they are given the thermode
- hypotensive showed shorter latency for pain threshold and tolerance
Why do they measure time (latency) in pain studies? What is time a proxy for?
- you’re interested in the temperature at which the person reacts
- time is a good proxy for temperature as long as you assume people’s skin all warm up at the same temperature
What is the verbal pain intensity scale?
-gives verbal descriptors (ex: severe, very severe) from no pain, to worst possible pain
What is the issue with VPS ? (Verbal Pain intensity scale)
- Can be hard to know exactly what each term means
- Hard to translate in order languages without altering the meaning of it
What is the NRS? (Numeric Rating Scale)
-Scale with numbers form 0 to 10, with sometimes some descriptors called pegs, for 0, 5, and 10.
What is a Visual Analogue Scale? (VAS)
-Line with pegs on left and right, and you put a stroke in the line corresponding to where your pain is at
Why is the VAS better than the NRS?
-VAS, much less likely to be biased by a number you gave before. (ex: chiropractor story)
What is the faces scale?
- faces showing different expression from good to bad.
- especially helpful with kids
What is the problem with the faces scale?
-no hurt: smiling. but this is not necessarily the case because not being in physical pain is not associated with being particularly happy.
What are things that are hard to capture in a rating?
- when? right now, last week, average last week, worst pain last week…
- in what context? at rest, at the end of the day, i the morning…
- pegs
What other ways are there to use rating scales?
-dual VAS using specific terms for the pain (eg, unpleasant, intense)
What did they find in a McGill study where they measured 2 pains, heat pain and ball blown in the oesophagus ?
- They wire the 2 pains so that are both a 4.
- They found that unpleasantness scores of oesophageal distension were alot higher than for heat pain.
About the two scales found on the internet that go from 0 to 10 with precise descriptions of each stage. Why are they not used in pain research?
-descriptions are asserted but no proof that they are true
How is the patient’s rating accuracy is confounded ?
-When patient is asked to rate their pain , they will often give a high number, because they want the doctor to take it seriously, and not make them feel like they came for no reason.
What is the problem with the interpretation of pegs?
- The individual interpretation of pegs depends on each people experience.
- A woman who has experienced childbirth pain has a larger scale than a man who hasn’t experienced kidney stone or gunshot wound.
What were the findings in the study where they compared the imagined pain of a certain pain state to the actual pain experienced by someone?
- General trend: people imagine that things are gonna hurt more than they actually do.
- But the sample size is to small to actually count on these results
What is the lumping and splitting problem with pain scales?
- attempt to list the things that contribute to the pain (ongoing pain, allodynia, hyperalgesia, functioning)
- the pain has alot of symptoms and alot of meanings but we’re boiling it down to a number. But how much of each symptom are responsible for the pain? we don’t really know. Maybe that’s way we stay on a single number.
How do you rate pain when the patient isn’t able to do it themselves? (eg. babies)
-FLACC Scale for babies: 5 categories are observed (face, legs, activity, cry, consolability). Rated from 0 to 2
How does the FACS (Facial Action Coding System) work?
Who created it?
- Paul Ekman
- coded the facial muscle action to infer emotions.
How was the McGill pain questionnaire developed ?
- Ron Melzack asked participants to come up with all adjectives they can think of that can describe pain.
- He made a questionnaire from these words. In each category you choose what word goes best with your pain.
- There is also a PPI: 6 points NRS.
- The idea is that it would be useful in diagnosis
- Problem: it’s long.
What is the DN4 questionnaire?
- 4 categories of questions
- 2 are patient interview
- 2 are patient examination
What is the oswestry disability index?
-Measures disability: how are people living with the pain
What are the three components of catastrophizing in the pain catastrophizing scale?
- Rumination: focus on negative content, generally past and present, and results in emotional distress.
- Magnification: exaggeration
- Helplessness
What is the controversy with the pain catastrophizing scale?
-Some people feel it decredibilizes their pain, makes them feel unvalidated, and like they don’t have the right to express their pain and be treated.
What is the WOMAC questionnaire?
- special questionnaire for arthritis.
- Not ideal as a pain questionnaire, but good to assess how bad the patient’s arthritis is.
What are the three main sections in the WOMAC questionnaire?
- Section A: context (walking, at rest, standing up…)
- Section B: Stiffness
- Section C: disability
What are the two types of testing and the stimulus done in the QST? (Quantitative Sensory Testing)
- Bedside examination
- Quantitative sensory testing: -Mechanical and thermal stimuli
What are the methods used in QST?
-Bedside examination, mechanical stimuli: paintbrush, cotton swab, gentle pressure with fingertip, pinprick
-Bedside examination, thermal stimuli: metallic roller kept at 20c or 40c, acetone/menthol.
-QST, mechanical: Von Frey Hair, Pressure alogometry
.QST, thermal: thermotest.
In an experiment with QST what are the temperature threshold relative to skin temperature?
- cool threshold: 31.1 C
- warm threshold: 37.7 C
- cold pain threshold: 13.8 C
- heat pain threshold: 43.5 C
According to a study with QST and heat hyperalgesia, how big is the change in pain heat threshold when the skin is injured?
-injuries cause anything from 4.8 to 5.6 degrees of hyperalgesia (meaning the pain threshold is 4.8 to 5.6 lower than on normal skin)
What was found in the study with QST and mechanical allodynia?
- applied dynamic mechanical stimuli on hurt side and unaffected side: no activation of nociceptive afferents on normal side, moderate pain on hurt side.
- three types of stimuli applied: cotton wisp, cotton-tipped, brush.
- Found: you would expect the brush to be more painful than qt because higher force exerted but it’s actually less painful.
What are the two types of PHN according t the german study with QST?
- PHN I: Peripheral and central sensitization, there is sensitization
- PHN II: deafferentation of small and large fibers, loss of function because they lost so many fibers.
In the german study according what does the QST parameter allow to make decisions on ?
The treatment used for the pain patients
What are the different ways in which you can cause pain directly onto a muscle?
- inject chemicals
- apply mechanical pressure
- apply intramuscular or intraneural electrical stimuli.
- apply miscellaneous stimuli with heated isotonic saline or focused ultrasound.
What is the dermatological biomarker of pain?
-tissue damage
What are the cardiovascular biomarkers of pain?
- heart rate
- blood pressure
- heart rate variability