Week 2 (Pain) Flashcards
Define pain
An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage
What is a noxious stimuli?
A stimulus that is damaging or threatens damage to normal tissues
What are nociceptors?
High threshold sensory receptor of peripheral somatosensory nervous system that is capable of transducing and encoding noxious stimuli
What is peripheral sensitisation?
Increased responsiveness and reduced threshold of nociceptive neurons in peripheral tissues
What is primary hyperalgesia?
Increased pain from a stimulus that normally provokes pain in the area of injury
What is central sensitisation?
Increased responsiveness of nociceptive transmission neurons in the CNS to their normal or sub-threshold afferent input
What is secondary hyperalgesia?
Spread of pain hypersensitivity beyond the area of tissue damage so that adjacent non-damaged tissue is tender, due to sensitisation of CNS
What is alloydnia?
A non-noxious mechanism or thermal stimulus is painful
Classification: Nociceptive pain
Pain that arises from actual or threatened damage to non-neural tissue and is due to activation of nociceptors (i.e. a normally functioning nervous system)
Examples of nociceptive pain
Bee stings, sprains, fractures, burns, bumps, bruises, inflammation, tumours
Classification: Neuropathic pain
Pain caused by a lesion or disease of the somatosensory nervous system (i.e. an abnormally functioning nervous system)
Examples of neuropathic pain
Sciatica, injury, spinal cord damage, nerve compression, phantom limb damage, carpal tunnel syndrome
Classification: Nociplastic pain
Pain that arises from altered nociception despite no clear evidence of actual or threatened tissue damage causing the activation of peripheral nociceptors or evidence for disease or lesion of the somatosensory system causing the pain
Examples of nociplastic pain
Fibromyalgia, complex regional pain syndrome, chronic low back pain, irritable bowel syndrome and bladder pain syndrome
What happens at the signal generator
Nociceptors detect a noxious stimuli and chemical substances activate and sensitise nociceptors
- Peripheral sensitisation
- Primary hyperalgesia
What happens at the amplifier
Mechanisms at the signal generator result in central sensitisation. Nociceptive input can cause changes in function and structure in the dorsal horn leading to amplification of signal transmission system and pain hypersensitivity.
- Secondary hyperalgesia
- Allodynia
What happens at the gain setter
Descending pathways from the brainstem to the spinal cord can modulate nociceptive processing and the experience of pain. Descending pain facilitatory and inhibitory systems function together to maintain a baseline however injury can result in dysfunction of pain inhibition and facilitation is always on. Descending modulation dysfunction can also happen in those with chronic pain where there is increased patterns of neuronal activation in pain-related cortical areas.
What can physiotherapists do to help with pain?
- Restore normal input to sensory nervous system
- Activate inhibitory pathways in the spinal cord and higher brain setters
- Promote positive neuroplastic changes to normal neural processes involved with pain experience
