What is chronic pain?
experiencing pain for 3 months of the year or more
How many adults experience pain?
What % of these are adult women and men?
37% adult women and 31% adult men
In which groups is chronic pain more prevalent?
Older people and low income households
How many times more likely are those experiencing pain going to visit the GP?
5 times more likely to visit the GP
What consequences can severe pain lead to?
What percentage of those with severe pain develop these consequences?
clinical anxiety and depression
69% of those with the most severe pain have these features
What % of adults reported pain in the last 12 months?
What % report more than 1 site of pain?
87% of adults reported 1 pain in the last 12 months
75% reported more than 1 site of pain
What is the consequence of having more pain sites?
More disability and distress
It is not simple cause and effect
How does the number of pain sites change with age?
What is this linked to?
it changes little after 20 years
There are links with maternal pain
Why is pain not an extraordinary experience?
It is a common day-to-day experience and a fundamental characteristic of living
What is congenital analgesia?
When someone cannot experience pain and register that their body is damaged
What does congenital analgesia lead to in childhood?
Increased amount of injury and physical health problems
Bones do not heal properly after being broken as children start becoming active far too early after injury
What is the IASP definition of pain?
An unpleasant and emotional experience associated with actual or potential tissue damage, or described in terms of such damage
What is meant by “potential tissue damage” is identifying the source of pain?
The root cause of pain may not be able to be found
There may be no detectable reason in a physical examination to describe why someone may be in pain
What is the alternative definition of pain?
Pain is what the patient says it is and exists when s/he says it does
How is detection of the intensity of pain linked to the alternative definition?
You cannot detect the intensity of pain and must go off the patient’s definition of where/how intense the pain is
Why is pain difficult to diagnose?
People build up their own internal representations of pain so it is a subjective experience
What are the 5 constructs used to assess pain?
- physiological - nocioception
What is meant by nocioception as a construct?
The physiological responses to threat
It can be measured but it is quite invasive
What is meant by sensory as a construct?
The quality and the intensity of the pain
What is meant by affective as a construct?
This is the unpleasantness of the pain and how it affects someone’s mood
What is meant by cognitive as a construct?
Expectations of pain and models of pain that are built up on previous experiences of pain
What is meant by behaviour as a construct?
How the individual vocalises their pain, how it affects their posture
What are typical pain behaviours?
- facial expressions
- para-vocalisation - “ouch”
- posture changes
- reduced behavioural repertoire
- taking pain relief
How is pain assessed using the pain thermometer?
The patient rates how bad their pain is on a scale of 1 to 10
This is repeated on a number of different occasions to see what factors changed their experience of pain
What is significant about the appearance of the pain thermometer?
It is a fixed point rating scale with vertical orientation
What are visual analogue scales in pain rating?
They are 100 mm long and a line that reaches from “no pain” to “extremely painful”
How are visual analogue scales used to rate pain?
The patient marks the severity of their pain on the scale
The distance from the start is measured to give a numerical value for the severity of the pain
Why are visual analogue scales preferred to the pain thermometer?
Scale of 0-100 rather than 0-10
this gives more reliability and reflects differences in people’s subjective experience to pain as it gives more precision in the way they communicate their experience
How does the McGill pain questionnaire work?
The patient picks out words that describes their current experience of pain
They colour in the body area affected
The pain rating index comes from summation of their pain descriptors
What are the descriptors in the McGill pain questionnaire?
- temporal (how much pain varies)
What is the standardised paediatric pain assessment?
Faces pain scale
The child picks a face or level between the faces that resembles how the pain makes them feel
Why is the faces pain scale reliable?
It is standardised
What was Descartes concept of the pain pathway?
It is a sensory experience and is reflex like
Peripheral receptors for pain lead to the brain
If pain is detected, the limb is moved away from the cause of the pain
What is Melzack and Wall’s pain theory?
Gate control theory
When the gate is open there is pain
When the gate is closed, the pain reduces
What is the analogy behind the gate control theory?
Modulation of pain happens around the level of the spinal cord
If there is a gate at the level of the spinal cord, it is opened in intense pain
This stimulates the C fibres (pain fibres)
In which 2 ways can the gate in the gate control theory be closed?
- stimulation of beta fibres
2. expectations/physiological processes that occur in your head
How does rubbing the elbow help with pain?
The beta fibres are touch/vibration fibres
This motion stimulates beta fibres to close the gate
sensory receptors are close to the pain receptors
What are bottom-up processes and how are they driven?
They are processes that organise incoming information
They are sensory driven
What are top-down processes and how are they driven?
They are processes that determine perception in ambiguous settings
They are driven by knowledge, experience and expectations
What is transcutaneous electrical nerve stimulation (TENS) used for?
Small battery is placed in pocket and 2 small electrodes are placed close to the area of pain
This stimulates large nerve fibres to try and close the gate
What conditions is TENS used for?
What is the clinical evidence?
- postoperative pain
- chronic musculoskeletal pain
Clinical evidence is not very good
What are the advances in the gate control theory?
- pain as a perception
- individual as active
- individual variability expected
- multiple causes of pain
What are the problems with gate control theory?
- there is no physical evidence of the gate
2. it still assumes an organic basis for pain
What is phantom-limb pain?
Phantom sensations experienced by almost all amputees
This pain is real, normal and occurs in the same position as the lost limb
How does phantom-limb pain change with progression?
It persists but the vividness often diminishes
How many amputees experience phantom-limb pain?
It is often stronger than other senses
What are changes in phantom-limb pain linked to?
Changes in mood, behaviour and environment
What method is used to reduce phantom pain of paraplegia?
The patient, who has no use of their legs, legs are hidden from view
The patient watches themselves walking in a in a mirror and this information is fed to the brain
How does pain in the legs change in paraplegia after using virtual walking?
15 days of virtual walking for 10 min/day
It addresses a motor output leading to sensory feedback mismatch
It changes the rating of pain and the areas un which pain appears
How does overall pain change after the virtual walking task?
Duration of pain relief increases
Pre-task pain decreases
What 3 characteristics make up what is painful?
- pain thresholds
sensation, perception, tolerance, encouraged/motivated tolerance
- pain duration
phasic, acute or chronic
- pain quality
superficial, deep, referred
What are the cultural differences in pain treatment?
Pain is subjective and differs between people
In some cultures it is more normal to express pain and talk about it
What is the positive Western cultural response to pain?
the stoical patient
they do not complain about pain or share their experiences
How is relative anaesthesia used to cope with acute pain?
It doesn’t change the intensity of the pain
It reduces the unpleasantness of the level of pain
What type of therapy is used to manage pain?
Cognitive-behavioural therapy is used in pain management
How does chronic pain threaten identity?
- it takes over so the patient feels trapped
- the changes their sense of body (makes them feel older)
- pain relief becomes their primary goal in life
What are the stages in the self-maintaining cycle of pain?
- tension and sleeplessness
- decreased pain tolerance
the cycle repeats and causes psychological distress
How are multidisciplinary clinics used to treat chronic pain?
- practical advice, physiotherapy and psychological interventions
- less reliance on medical controls
- allows for social and family support