- Chronic post surgical pain (CPSP)
- Most have a neuropathic element, but not all
- Can occur in >50% in mastectomy, thoracotomy, amputation
- Central sensitisation occurs and there is dorsal horn activity which amplifies sensory flow, and can lead to death of inhibitory neurons and microbial activation.
- Any link between nerve damage and pain is tenuous and complex
- Risk factors for CPSP
- Existence of severe pre-op pain (> 1 month)
- Increasing age is inversely related
- Genetic susceptibility
- Polymorphisms of COMT, for example
- Longer and more complex procedures
- Laparoscopic is associated with less CPSP
- Adjuvant treatments eg RXT
- Future developments
- Minocycline has an inhibitory effect on microglial cells
- Dorsal horn purogenic receptors have been implicated in the development of CPSP and their inhibition may prevent its development.
- Altered expression of Na⁺ channels occurs in animal models, and their blockage has altered animal pain behaviour
- Preventative anaesthetic techniques
- Little benefit from pre-emptive regional anaesthesia (pre-incision)
- Preventative regional anaesthesia (eg epidural post op) has reduced CPSP after laparotomy and thoracotomy. Paravertebral block, if continued post op, may reduce mastectomy CPSP.
- Gabapentin failed to reduce amputation CPSP
- Clonidine with the LA and ketamine infusions are also under investigation
- Limited evidence for multimodal approaches
- CEACCP
Link:ceaccp.oxfordjournals.org/content/10/1/12.full.pdf