Preventive analgesia: Preventive analgesia is a broad term used to describe an analgesic regime given during surgery to control post - op pain and its aim is to reduce the impact of the process known as central sensitization. This refers to an increase in synaptic efficacy in the somatosensory neurons following tissue injury (e.g. surgery) or nerve damage. This leads to a reduction in pain threshold, an amplification of pain responses and a spread of pain sensitivity to non-injured areas resulting in increased post -op pain intensity and analgesic requirements. Preventive analgesics (including nerve blocks) have been incorporated into a range of surgical procedures, with a recent review identifying its strong positive impact on post-operative pain and analgesic consumption.