What is pain?
Pain is ‘an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage’1. It is a subjective perception resulting from the brain’s interpretation of inputs and expectations.
Pain perception may be a consequence of:
- noxious stimuli that threaten or damage tissues (see What is nociception? and nociceptive pain in Pain types)
- damage to certain sensory nerves, spinal cord or brain pathways (see neuropathic pain in Pain types)
- sensitisation processes that affect areas of the spinal cord and brain involved in modulating and perceiving pain (see nociplastic pain in Pain types).
The inability to communicate verbally (eg infancy, dementia) does not negate the possibility that an individual is experiencing pain and is in need of appropriate pain management; pain may be perceived from 28 weeks’ gestational age.
The function of acute pain is to alert the body to a potential threat, prevent the body from further harm (eg by moving away from the trigger), and to learn to avoid similar harm in the future. Although pain accompanying chronic conditions may continue to serve these functions, chronic pain often occurs in the absence of tissue damage or noxious stimuli.
Patients often find the concept of pain difficult to understand. Videos that can assist clinicians when explaining pain to patients can be found here.