Pain Flashcards
Define pain
Unpleasant sensory and emotional experience associated with, or resembling that associate with actual or potential tissue damage
Define immediate pain
Warns of imminent tissue damage - withdraw from source of injury
Define persisting pain
After immediate pain
Encourages us to immobilise the injured area, giving damage the best chance to heel
Define nociception
Describes neural processes involved in producing and the sensation of pain
Define nociceptive pathways
Transduction in the periphery, through transmission to the dorsal horn of the spinal cord, then on to the brain
What are the phases of pain
Phase 1 - instant
Phase 2 - acute
Phase 3 - chronic (abnormal)
Define acute pain
< 12 weeks duration
Define chronic pain
Continuous pain lasting > 12 weeks
Pain that persists beyond the tissue healing time
Chronic non-cancer pain vs chronic cancer pain
Define nociceptive pain
Pain that arises from actual or threatened damage to non-neural tissue and is due to the activation of nociceptors
Define neuropathic pain
Pain causes by a lesion or disease of the somatosensory nervous system
Define 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 pain
Define allodynia
Pain due to a stimulus that does not normally provoke pain
Define dysesthesia
An unpleasant abnormal sensation whether spontaneous or evoked
Define hyperplasia
Increased pain from a stimulus that normally provokes pain
Define hypoalgesia
Diminished pain in response to a normally painful stimulus
What is the pain pathway
Peripheral receptor - detect relevant stimuli
1st order neuron - from the periphery to the ipsilateral spinal cord
2nd order neuron - which crosses to the contralateral cord and ascends to the thalamus, the systems integrative ‘relay station’
3rd order neuron - from thalamus to midbrain and higher cortical centres
Define nociceptors
Free nerve endings of primarily afferent neurones
A delta fibres
C fibres
Found in any area of the body which can sense pain either externally and internally
Where do cell bodies of nociceptors usually reside
Dorsal root ganglion (body)
Trigeminal ganglion (face/head/neck)
Describe a-delta nerve fibre
Information carried
Myelin sheath
Diameter
Conduction speed m/s
Pain - mechanical and thermal
Myelinated
1-5micrometers
5-40m/s
Describe C fibres
Information carried
Myelin sheath
Diameter
Conduction speed m/s
Pain - mechanical, thermal and chemical
Non-myelinated
0.2-1.5micrometers
0.5-2m/s
Where is the degree of pain is judged
Insula
Contributes to subjective aspect of pain perception
What can hyperactivity of the central nucleus of the amygdala cause
Pain-related emotional response
Anxiety-like behaviour
What maintains reciprocal connections with other pain processing areas
Cingulate cortex
What is the role of opioids in pain
a2-adrenoceptor agonists
Inhibit afferent nerve transmission (descending pain pathway)
3 types of opioid receptors which regulate the neurotransmission of pain signals
Can regulate pain within the spinal cord, brain stem and cortex
Describe the descending pain pathway
Neuronal inhibition
Midbrain receives pain information sends information via the spinomescencephalic tract - processes nociceptive information and relays to the rostral ventral medulla
Send signals down spinal cord and activate endogenous opiate systems to supress pain
