Mechanism & Risk factors for Chronic Pain

Question 1

Define pain

Answer 1

An unpleasant sensory & emotional experience associated w/ actual or potential tissue damage

Question 2

Why do we experience pain?

Answer 2

Pain as a homeostatic emotion:

• signifies a threat to bodily integrity.
• a specific emotion that reflects homeostatic behavioural drive.
• Requires & drives “action”

Question 3

How is pain classified?

Answer 3

1. Nociceptive:
   - Pain arising from activation of nociceptors following tissue injury
   - Aδ & C-fibre terminals
   - Proportionate to injury
   - Protective
   - Enables healing w/ resolution of pain
   - Learn future avoidance
   - Physiological
2. Neuropathic Pain:
   - Pain arising from disease or damage to nervous system
   - Frequently long-lasting
   - Pain not proportional to tissue injury
   - Pain serves no “benefit”
   - e.g. fibromyalgia, cancer pain, persisting post-surgical pain
   - Pathological

Question 4

What is a key factor in chronic pathological pain?

Answer 4

The limbic system

The limbic system is the emotional brain
- Reward
- Anxiety
- Mood
- AND PAIN – the “unpleasantness” component…we can’t ignore it.

Enhanced activation of the limbic system amplifies the negative interoceptive state.(Interoception is sensing internal body state.)

Made up of:
- amygdala
- hippocampus
- thalamus
- hypothalamus
- basal ganglia
- cingulate gyrus.

Question 5

How is pain perceived? Which areas of the brain are involved?

Answer 5

1. Nociceptive input from tissue damage enters superficial dorsal horn through Aδ fibres.
2. Enters spinothalamic tract pathway.
3. The brainstem, thalamus & interoceptive cortex are areas which are associated w/ assessing body’s interoceptive state rather than assessing where & how large the pain is.
4. Activation of these areas produces a negative effect & the need to alter behaviour.
   - This aims to alleviate a perceived threat or achieve a reward.

Question 6

How do you modify distress and emotion - stop an overactive limbic system?

Answer 6

• Physiotherapy
• Occupational therapy
• Education
• Pain Management Programme
• Psychological therapies e.g. Cognitive Behavioural Therapy. NOTE: psychology can change things biochemically that cause pain.
  
  • Reduction in IL-6
  • Reduction in TNF⍺

Question 7

Lifestyle risk factors for chronic pain?

Answer 7

• smoking
• drinking
• inactive lifestyle

Question 8

Demographic risk factors for chronic pain?

Answer 8

• female
• age (over 45 yrs)
• socio-economic status - depravation increases risk.
• employment - more common in the unemployed & manual workers.

Question 9

Clinical risk factors for chronic pain?

Answer 9

• Acute back pain with neurological signs.
• Multimorbidity
• History of trauma or chronic pain
• Obesity
• Sleep disorders
• Psychological distress

Question 10

Psychological risk factors for chronic pain?

Answer 10

Attitudes & beliefs about pain:

• Active beliefs- where individuals have strong self-efficacy beliefs & see pain as malleable (i.e. they can change it).
• Passive beliefs - hoping pain will get better.
• Catastrophizing pain - i.e. “It will never get better” Associated w/ worse pain & psychological dysfunction.
• Health beliefs e.g. if individuals belief their pain is caused by damage, they are more likely to avoid doing things that encourage pain = leads to physical mobility reduction.

Question 11

Social risk factors for chronic pain?

Answer 11

Identity - patients can feel pride in not complaining & maintain a stoic face in order to keep their identity of being ‘strong’.

Interpersonal relationships- people w/ chronic pain often describe friends, family & colleagues as being suspicious which leads to coping strategies such as concealing the illness. - Strong relationships can, however, provide resilience & aid.