Table 4.

Glossary of terms used in the neurophysiology of pain

Term	Explanation
Peripheral sensitisation	Reduced pain thresholds that occur following tissue damage, which are caused by an increase in the concentration of chemical mediators in the damaged tissue. There are many mediators of peripheral sensitisation and as a group they are called eicosanoids
Central sensitisation	Reduced pain thresholds that occur following tissue damage, which are caused by altered sensitivity of the nociceptive pathways because of repeated stimulation. The main sites of central sensitisation are the dorsal horn of the spinal cord and the higher centres of the brain, especially the cerebral cortex
Hyperalgesia	Increased pain due to stimulation of damaged tissue by a stimulus that would normally be perceived as painful. The stimulation is felt as more painful than it would be if the tissues were not damaged. Hyperalgesia is a clinical sign of peripheral and central sensitisation
Allodynia	Pain due to stimulation of damaged tissue by a stimulus that would not normally be perceived as painful. The stimulation is felt as painful because the tissues are damaged. Allodynia is a clinical sign of peripheral and central sensitisation
Persistent postoperative pain	Pain perceived following surgery that lasts longer than it usually would. Persistent postoperative pain is a common consequence of poor or absent pain relief at the time of surgery

Adapted from Steagall et al (2021) ⁴⁴