Pain Flashcards
What is the definition of pain
an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such danger
what is the classification of acute pain
short term, less than 12 weeks duration
what is the classification of chronic pain
continuous long term pain, more than 12 weeks duration OR pain tat persists after the time that healing would have been theought to have occurred after trauma/ surgery
what are the divisions of chronic pain
cancer pain and chronic non-cancer pain
what are the 3 parts of coping with chronic pain
Pacing, Planning, Prioritising
what is a flare up (in terms of pain)
increase in patient’s usual pain; not a new pain sensation
what is the definition of nociceptive pain
pain that arises from actual or threatened damage to non-neural tissue and is due to the activation of nociceptors
- used in conjunction with a normally functioning somato-sensory system
what is the definition of neuropathic pain
pain arising as a direct consequence of a lesion or disease of the somato-sensory system
what does allodynia mean
pain due to stimulus that does not normally provoke pain
what does dysesthesia mean
an unpleasant abnormal sensation, whether spontaneous or evoked
what does hyperalgesia mean
increased pain from a stimulus that normally provokes pain
what does hypoalgesia mean
diminished pain in response to normally painful stimulus
what does hypoesthesia mean
dimisinished sensitivity to stimulation, excluding special senses
describe the path of 1st order/ primary afferent neurones of the pain response
enter spinal cord through spinal nerve or brainstem through CN V, ipsilateral to peripheral receptor
Remain ipsilateral and synapse with 2nd order neurones in the CNS
describe the path of 2nd order neurones in the pain responses
cell body located in spinal cord/ brainstem
axons decussate to other side of CNS and ascend to thalamus where it terminates
describe the path of 3rd order neurones in the pain response
cell body located in thalamus
axon projects to somatosensory cortex in post central gyrus of parietal lobe
what are nociceptors
sensory neurones found in any area of body that can sense pain either externally or internally
where are the cell bodies of nociceptors
dorsal root ganglion (body) or trigeminal ganglion (face/ head/ neck)
what can cause hyperalgesia
presence of tissue damage/ bradykinin/ prostaglandin E2 can reduce nociceptive AP threshold so increase sensitivity to stimuli
what is the modality of nociceptors generally
poly-modal; thermal/ chemical/ mechanical
what are the 2 type of afferent fibres associated with the pain response
alpha delta fibres and c fibres
describe alpha delta fibres
thinly myelinated
carry touch, pressure, temperature, FAST pain information
small diameter; 1-5 microns
medium conduction speed; 5-40m/s
describe c fibres
unmyelinated
carry SLOW pain, temperature, touch, pressure, itch, postganglionic autonomic fibres information
smallest diameter - 0.2-1.5 micrometers
slowest conduction speed; 0.5-2m/s
what sort of neurones are a delta and c fibres
1st order
nociceptors
where do 1st order neurons synapse with 2nd order neurones in the pain pathway
substantia gelatinosa in grey matter of dorsal horn of spinal cord
describe a delta terminals
release glutamate as neurotransmitter
- fast acting
describe c fibre terminals
release glutamate and substance P as neurotransmitter
- slow acting, involved in mediation of dull aching pain
what does the spinothalamic tract carry
pain, temperature, crude touch from body
where does the spinothalamic tract enter the spinal cord
Lissauer’s fasciculus
what does the trigemino-thalamic tract carry
pain, temperature, crude touch from face/ head/ neck
where does the trigemino-thalamic tract receive contributions from
CN 5, 7, 10, 12
what does the lateral spinothalamic tract carry
pain and temperature
what does the anterior spinothalamic tract carry
crude touch
where do the spinothalamic/ trigemino-thalamic tracts terminate
ventral posterior lateral nucleus of thalamus
what tracts are involved in the pain response
spinothalamic and trigemino-thalamic
describe dorsal root ganglion
on dorsal root
composed of cell bodies of nerve fibres that are sensory - afferent
pseudo-unipolar neurons
1st order neurons
what are the functions of the nuclei in the thalamus
relay and association
what is the role of the insula
where degree of pain is judged - contributes to subjective aspect of pain perception
where is the insula
within brain via sylvian fissure
where is the cingulate gyrus
medial aspect of cerebral hemispheres
what is the role of the cingulate gyrus
linked with limbic system; involved in emotional response to pain and associated with emotion forming/ processing learning and memory
what the periaqueductal grey
grey matter around aqueduct in the midbrain
where does the periaqueductal grey receive input from
somatosensory cortex (Brodmann 1,2,3)
what pathway is the periaqueductal grey involved in
descending pain pathway
when is the periaqueductal grey activated and why
activated in situations of high stress and contributes to modulation of afferent noxious transmission
has high concentration of opioid receptors and endogenous opioids
where does the periaqueductal grey project to
dorsal horn
what happens when the periaqueductal grey is activated
opioid receptors are activated leading to reduction in pre-synaptic neuronal sensitivity so reducing substance P release so reducing pain sensation
- less impulses travel up 1st/2nd/3rd order neurons to somatosensory cortex so less pain felt
what do opioids do
bind to opioid receptors in periaqueductal grey so reducing pre-synaptic neuronal sensitivity
-result in profound analgesia
what is the definition of analgesia
selective suppression of pain without effects on consciousness/ other sensation
what is the definition of anaesthesia
uniform suppression of pain
- sometimes consciousness is lost e.g. general anaesthetic
what is the Melzack-Wall Pain Gate theory
states that non-painful input closes the gate to painful input
- preventing pain sensation from travelling to the somatosensory cortex to be perceived and thus felt
what are some treatments for pain
analgesics
acupuncture
exercise
hypnotherapy
what is substance P
Peptide neurotransmitter involved in pain transmission
-also a vasodilator
remains bound to receptors for longer time so transmits long lasting pain
