1. Basics of chronic pain
Venugopal Kochiyil
Rehabilitation and Pain Medicine Physician

2. Pain
• An unpleasant sensory and emotional experience
associated with actual or potential tissue damage or
described in terms of such damage (IASP)
• Acute and chronic pain
• Somatic and visceral pain
• Nociceptive and neuropathic pain

3. Chronic pain
• Pain that persists beyond the expected time frame for
a given disease or injury
• May not have any temporal relationship with the
inciting cause
• Maladaptive
• Time frame?
• Pain without apparent biological value that has
persisted beyond the normal tissue healing time (3
months) - IASP

4. Neuropathic pain
IASP clinical update September 2010

5. Neuropathic pain
IASP Pain Update
September 2010

6. http://www.medscape.org/viewarticle/498353

7. Process by which we feel pain
• Transduction – noxious stimulus converted to
electrical impulse by nociceptors
• Transmission – Transmission of these impulses from
periphery to spinal cord and brain
• Perception – Appreciation of these signals arriving in
the higher structures
• Modulation – What influences nociceptive
transmission

8. Ascending tracts

9. Cortical and subcortical connections

11. Peripheral sensitization

13. Wind up – Temporal summation
• Repeated peripheral stimulation causes increased
firing at the level of DH
• NMDA receptors play a key role

14. Central Sensitization
• Nervous system gets upregulated in a persistent state
of high reactivity – a state of hyperexcitability
• Tissue injury and nerve injury can cause this
• Continue even after stimuli has stopped
• Associated with reduction in central inhibition,
spontaneous dorsal horn activity, alteration of
neuronal connections
• Allodynia and hyperalgesia, persistent pain, referred
pain

15. Woolf CJ. Pain 2011;152(3): S2-15

16. Central sensitization
Woolf CJ. Pain 2011; 152(3):S2-15

18. Cortical plasticity

20. Psycholoy – Affective - Depression
• More prevalent in chronic pain than other chronic
illness
• Prevalence varied in studies (10 – 75%)
• Somatic symptoms of depression in common in
patients with chronic pain
• What is the first symptom
• Predictors
• High levels of pain, less activity, greater
disability, pain behaviours

21. Psychology – Affective - Anxiety
• High levels of anxiety is another disabling effect of
chronic pain
• Activity avoidance
• Implicated in imbalance between excitatory and
inhibitory descending system

22. Psychology – Affective - Anger
• Up to 70% had anger feelings – towards themselves
or others
• Anger was related to pain intensity and decreased
function
• Perceived injustice
Burns JW, Gerhart JI. Health Psychol 2015;34(5):547-55
Scott W, Trost Z. Pain 2013;154:1691-8

23. Cognitive factors
• Passive life style / passive coping
• Somatic focus
• Pain related fear
• Pain Catastrophizing
• Kinesiophobia
• Maladaptive behaviours

24. Sleep
• Relationship is well documented
• More than 50% of patients are affected
• Decreased quality of sleep, longer sleep latency and
fragmented sleep
• Associated with depression, Diabetes, obesity
• Sleep disturbances may be a stronger predictor of pain
• Sleep deprivation increases pain sensitivity
• Affect pain processing in multiple levels of neuaxis
Finan PH, Goodin BR. J Pain 2013; 14 (12): 1539-1552