pain review Flashcards
pain define
unpleasant sensory and emotional experience associated with actual or potential tissue damage
an unpleasant sensory or emotional experience associated with or resembling that associated with, actual or potential tissue damage
- Pain is always a personal experience that is influenced to varying degrees by biological, psychological, and social factors.
- Pain and nociception are different phenomena. Pain cannot be inferred solely from activity in sensory neurons.
- Through their life experiences, individuals learn the concept of pain.
- A person’s report of an experience as pain should be respected.
- Although pain usually serves an adaptive role, it may have adverse effects on function and social and psychological well-being.
- Verbal description is only one of several behaviors to express pain; inability to communicate does not negate the possibility that a human or a nonhuman animal experiences pain.
models of pain
How can it be possible
to experience pain
without tissue damage?
How can it be possible to
experience tissue damage
without pain?
How can it be possible to
experience pain after
tissue damage has healed?
i.e. chronic pain
Pain system can be overrrided for short period of time to allow you to get to safety
clinical relevance
insidious onset of pain - muscle recognise presence of ongoing irritant and remove to stop cycle of tissue micro trauma
models of pain - chronic / persistent
biopsychosocial model
social - culture
social interactions
psycho - illness behaviour
beliefs, coping strategies
emotions, distress
bio - neurophysiology
physiologic dysfunction
(tissue damage)
pain pathways
Nociceptors are free or bare nerve endings that respond to painful stimuli.
Joint capsule & periosteum are most sensitive tissues, followed by subchondral bone, tendons and ligaments.
Pain receptors are supplied by variety of different nerve fibres
only when it hits cerebral cortex do you perceive pain
nociceptors
A delta fibres (smaller than a beta) Mechanical 1st / Fast Pain Well-localized Sharp / Prickling Glutamate neurotransmitter
C fibres - slow fibres Polymodal 2nd / Slow Pain Diffuse Dull Aching Burning Substance P neurotransmitter
spinothalamic
pain signals are filtered selected and modulated at every level
pain signals
descending innibitory system
primary source is periaqudcutal grey matter
inhibit downward towards the dorsal horn
direct structural components from limbic system
neuromatrix
Spinal cord & brain are best seen as integrated Neuromatrix not simply tracts – i.e. computer
Other inputs can modify pain signals – basis for Rx
Pain strongly linked with emotions – limbic system
Stress, endocrine responses, autonomic & immune system inputs & mental functions
CNS is plastic – neurophysiology changes over time with development of chronic pain
Pain and nociception are different phenomena: the experience of pain cannot be reduced to activity in sensory pathways
CNS very plastic
related to pain
neuroplasticity + pain
system has potential to experience chronic pain
pain and nociception are different phenomena
hyperalgesia
primary and secondary
Hyperalgesia: increased pain from a stimulus that normally provokes pain
more nociceptive drive from periphery causing more irritation
Primary Hyperalgesia: increased sensitivity to input at the site of the injury and due to processes in damaged tissues. It is largely due to the sensitisation of peripheral nociceptors.
Secondary Hyperalgesia: sensitivity in uninjured tissues around the original injury. This is most likely to arise from central mechanisms.
Allodynia: pain evoked by stimuli that are not normally painful
e.g. touch or cold / heat
neuropathic pain
Neuropathic Pain: Pain caused by a lesion or disease of the somatosensory nervous system.
Peripheral Neuropathic Pain: Pain caused by a lesion or disease of the peripheral somatosensory nervous system.
Central Neuropathic Pain: Pain caused by a lesion or disease of the central somatosensory nervous system.
nociplastic pain
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.
central sensitisation
Central sensitization: Increased responsiveness of nociceptive neurons in the central nervous system to their normal or subthreshold afferent input.
peripheral sensitisation
Peripheral sensitization: Increased responsiveness and reduced threshold of nociceptive neurons in the periphery to the stimulation of their receptive fields.
neuropathy
a disturbance of function or pathological change in a nerve. eg radiculopathy
in one nerve, mononeuropathy; in several nerves, mononeuropathy multiplex; if diffuse and bilateral, polyneuropathy
nociceptive pain
Nociceptive Pain (Somatic Pain):
Dull, deep, aching type pain.
Mechanical / physiological processes in injured tissue: tends to be localised.
Predictable response to stretch, compression or movement
Responds to simple painkillers & NSAIDs
Improves with appropriate passive (manual) treatment
types of spinal pain Referred / nonradicular pain = any somatic structure of spine causing pain with referral
Radicular pain = caused by spinal nerve or root e.g. radiculopathy – disc bulge irritating nerve root in foraminal space e.g. L5/S1
