Pain Flashcards
Differentiate between nociception and pain
Nociception - non-conscious neural traffic originating with trauma or potential tissue trauma
Pain - complex, unpleasant awareness of a sensation
Differentiate between stimulus threshold and stimulus tolerance
Threshold - same for everyone
Tolerance - variable reaction to a painful stimulus
Discuss the ascending pathways of pain and their projection to the brain
Lateral spinothalamic tract = pain
Direct (fast) lateral STT - discriminative pain, contralateral, no synapses in brainstem, parietal lobe, temperature, crude touch, from lamina I, IV, V
Indirect (slow) lateral STT - affective (arousal), bilateral, synapses in brainstem, hypothalamus, reticular formation, limbic structures, from lamina I, IV, V (VII, VIII) e.g. spinoreticular, spinomesencephalic, spinotectal, spinohypothalamic
List the stages of nociception
Transduction
Transmission
Modulation
Perception
Define the terms ‘transduction’, ‘transmission’, ‘modulation’, ‘perception’ in respect to pain
Transduction - activation of nociceptors by a stimulus
Transmission - relay of action potentials along nociceptive fibres to CNS
Modulation - by other peripheral nerves or CNS mechanisms
Perception - interpretation by brain that stimulus is painful
Describe the different types of pain fibre
A Y (A delta) - sharp, stabbing pain, well localised, first pain/phase 1, lower threshold, initiates withdrawal reflex C - dull, throbbing pain, poorly localised, second pain/phase 2' higher threshold, tissue damage occurs
Discuss methods of pain modulation
Analgesia - hypnosis, morphing, TENS
Central - gate control (massage, acupuncture), endogenous opioid peptide analgesics e.g. enkephalins, endorphins, dynorphins
Define the term ‘chronic pain’
Pain/discomfort persisting continuously/intermittently for 3 months/12 weeks
Define the terms ‘hyperalgesia’, ‘allodynia’
Hyperalgesia - increased pain at normal threshold stimuli
Allodynia - pain from not normally painful stimulus, pain occurs other than area stimulated
Explain the concept of ‘wind up’ pain
Tissue injury and nerve damage may cause persistent activation –> increased glutamate release, increased NMDA receptor activation –> long term changes in nociceptive neurones –> hyperexcitable
Can lead to receptive field expansion
List different types of pain
Acute Chronic: Nociceptive - arthritis Neuropathic - central/peripheral Visceral - organ disease, inflammatory Mixed - cancer, lower back
Discuss chronic pain syndromes, causes and signs/symptoms
Complex Regional Pain Syndrome Type 1 - no identifiable lesion Type 2 - identifiable nerve lesion Causes - minor trauma, bone fracture, surgery, stroke, MI Signs/symptoms - severe continuous burning pain, hyperalgesia, allodynia, temperature asymmetry, skin colour asymmetry, oedema, sweating changes, decreased range of movement, motor dysfunction Stage 1 - acute Stage 2 - dystrophic Stage 3 - atrophic
Describe the differences between T1 and T2 weighted MRI scans
T1 (useful for assessing cerebral cortex, identifying fatty tissue):
Bright - fat, blood, protein rich fluid
Dark - water, low protein density, calcification
T2 (useful for detecting oedema and inflammation)
Bright - water
Dark - low protein density, calcification, fibrous tissue, protein rich fluid
Define the term ‘pain’
An unpleasant sensation and emotional experience associated with actual or potential tissue damage
Visceral or somatic origin
Elicits sensation with autonomic, somatic, endocrine and emotional responses
List three types of painful stimuli
Chemical (prostanoids, histamine, substance P, acids)
Mechanical (distension of skin, pressure)
Thermal (extremes of hot or cold)
