Measurements

Pain threshold vs tolerance

• threshold is when something becomes pain

• Tolerance is when pain gets too much to handle

Time is a proxy for __

temperature, latency is the measure of time

Rating Scales of pain: VAS

visual analogue pain scale

• coding faced and using it as measure

• good for animals and kids

NRS pain scale

numeric pain intensity,

• 11 categories because 0 is one

3 questions for context in pain rating scales

1. when are you measuring pain: average/now/average of last week

2. in what context: at rest/standing

3. pegs: what is the worst possible pain/unbearable

Issue with alternative pain scales: 4

1. decriptions are arbitrary

2. person giving the rating has different goal than person asking

3. scale differences

4. real vs real

Issue with alternative pain scales: descriptions being arbitrary

the order of the descreiptive words are arbitrarily chosen

Issue with alternative pain scales: rater vs rating

have different goal

• person giving rating might want drugs/help/resources

Issues with alt pain scale concepts: scale differences

• subjective scale differences eg women and childbirth

which is normally larger, real pain or imagined how much pain

imagined except in childbirth

What is “driving” clinical pain scores by order

1. ongoing pain

2. allodynia

3. hyperalgesia

4. functioning

Non self report scales 2

baby pain and facial pain scale

facial pain coding is reliable becasue it seems to be…

stable across culture

overview of malzack’s pain descriptor study

compiled and rated pain words

• not very uselful except for differentiating neuropathic pain becasue iots described as electric or burning

what is the DN4

a neuropathic pain questionnair

• faster way to distinguish neuropathic paon

hypoasthetia means

numbness

The DN4 has two parts

the interview and the examination

Oswesty disability index

measures non direct variables of pain

• impact of pain on life

pain catastrophising scale

measures rumination, magnification and helplessness

The WOMAC questionnaire is for what

arthritis

which questionnair is for arthritic pain

WOMAC

which questionnaire is for measuring the impact of pain on other life functions

Oswestry

QST relies on

examination and test, no questionnaire

QST overview

quantitative sensory testing

• measures touch/cold/warm/thresholds and tolerances

• bedside or clinical methods

QST: clinical mechanical stimuli

from low to high order or vise versa to find detectable threshold

QST clinical thermal tests

find where pain starts

cold pain normally starts at__ degress and hot at __

14 and 43

what is the german way of QST

seperating pain, learn its type and bio underpinnings

• gain of function vs loss of function differences

QST is good at identifying what

neuropathy not neuropathic pain

Biomarkers of pain: cardio vasc

HR, BP and HR variability

Biomarkers of pain: stress related

cortisol

galvanic skin response

Biomarkers of pain: Neural

• EEG

• microneurography C fibers

• imaging

Biomarkers of pain: Chemical

level of chem is corr with pain

• substance

• nerve growth factor

Biomarkers of pain: Molecular

• DNA

• mRNA

issue with molecular biomarkers of pain

DNA doesnt chnage since conception

FMRI as biomarker of pain

yes imaging agress with pain ratings but it also compares with hipnotic and imagined pain

why use animals in pain research

can find causation control for genetics

why has mice research taken off

because of ability to edit genes

one reason animal research is an issue (prey)

animals tend to hide pain becsue they are prey

2 ethical schools of pain research

1. deontological

   • morality of the action is dependent on whether the action aligns with set of rules

2. consequentioalist

   • what matters i sthe consequence of what we do

Algesiometry in Rodents: 6 types of pain measurement

1. chemical

2. cold

3. electrical

4. heat

5. mechanical

6. spontaneous

thermal assays: 2 acute thermal pain threshold measures

1. hot plate: measure how fast rats respond

2. tailflick: use tailflick as reflex for pain, dip foot in water

Thermal assays: hargreaves

put on glass shine heat on one paw, good because you can target one paw

Mechanical Assays: 2

von frey fiaments

randall selitto

Mechanical assays: Von frey

use fibers to poke foot, find fibre that causes withrawal 50% pf the time

randall selitto tests can be used on all rodents T or F

false, only rats

Mechanical Assays: randall selitto

measure of wriggles after force is dropped on paw

indirect mechanical assays overview and three types

1. induce pain in animal

   • weight bearing eg if mouse is guarding one foot

   • grip force

   • gait, favouring certain paw

Chemical assays: 2

writhing test

formalin test

Chemical assays: writhing

inject acetic acid into stomach, causes constriction

Chemical assays: formalin test

inject formaldahide

• measure licking

which assay shows an interesting time course of pain

formalin

• increases, decreases then peaks at late phase

Tonic chronic inflammatory assays

• injecting chem that lasts a long time and simulates chronic pain

• then measure

  • thermal hyperal

  • mechanical allod

  • cold allod

chronic neuropathic assays

damage some nerve then measure thermal hyperalgesia, cold and mechanical allodynia

axotomy vs partial denevation

cutting entire nerve vs only some

autotomy

biting off a ligament after axotomy

examples of chronic neuropathic assays

giving a virus or inducing other issues with an animal and then measuring pain

eg HIV or diabetes

big three criticisms of animal models

1. reflexive vs conditioned measures

2. pain affected measures

3. symptom epidemiology vs dependent measure use

Reflexive vs conditioned measures

• reflexive is not reflective of clinical pain

• new idea is to get animal to make decision based on pain and a thing it wants

conditioned place preference to analgesia

measure how much time rat spends in the side of the rooom which is the analgesic

Pain affected measures (sleep/anxiety)

we dont’t measure them in animals and they are important to clinical pain

disconnect between symptoms that are common in humans vs animal

issue with animal research we use facial pain scales yet certain animals don’t do some pain related reflexes