Physiology and Pathophysiology or Pain Flashcards
What is pain?
An unpleasant sensory and emotional experience which we primarily associate with tissue damage or describe in terms of such damage or both
What is nociception?
The detection of tissue damage by specialised transducers connected to A-delta and C-fibres
What are the basic steps in the pathway of pain?
Periphery, Spinal cord, Brain, Modulation
What are nociceptors?
Free nerve endings of A-delta and C-fibres that respond to thermal, chemical, mechanical noxious stimuli
Where are primary afferents located and synapse?
Cell body in dorsal root ganglion
Synapse at spinal cord
What is the difference between A and C fibres?
A fibres conduct sharp pain
C fibres conduct dull pain
What type of tract in the spinal dorsal horn takes charge of pain?
Lateral spinothalamic tract
Where does the spinothalamic tract arise?
Rexed lamina 2 and 5
Where does pain perception occur in the brain?
Somatosensory cortex
What change occurs in the nociceptor with allodynia?
Decreased threshold for response
What change occurs in the nociceptor with hyperalgesia?
Exaggerated response to normal and supernormal stimuli
What change occurs in the nociceptor with spontaneous pain?
Spontaneous activity in nerve fibres
What is central sensitisation?
Response of second order neurons in the CNS to normal input both noxious and non-noxious
What are the 3 components of central sensitisation?
Wind-up
Classical
Long-term potentiation
What are the key points of wind up in central sensitisation?
Only involves activated synapses
Homosynaptic activity dependent progressive in response to neurons
Manifests over courses of stimuli an terminates with stimuli
What are the key points of classical in central sensitisation?
Involves opening new synapses
Heterosynaptic activity dependent plasticity
Immediate onset
Outlast the initial stimuli duration
What are the key points of long term potentiation in central sensitisation?
Involves mainly activated synapses
Occurs primarily for very intense stimuli
What are the differences between acute and chronic pain?
Acute: presence of noxious stimuli, usually nociceptive
Chronic: Noxious stimuli not essential, nociceptive, neuropathic or mixed
What is neuropathic pain?
Pain initiated or caused by a primary lesion or dysfunction in the tomato-sensory nervous system
What can be used to treat neuropathic pain?
Anti-depressants and anticonvulsants
What are the treatment options for pain associated with transduction?
NSAIDs
Ice
Rest
LA blocks
What are the treatment options or pain associated with transmission?
Nerve blocks Opioids Anticonvulsants Cordotomy DREZ
What are the treatment options for pain associated with perception?
Education Cognitive behavioural therapy Distraction Relaxation Graded motor imagery Mirror box therapy
What are the treatment options for pain associated with descending modulation?
Placebos
Opioids
Antidepressants
Spinal cord stimulation
