Pain mechanisms Flashcards
What are the 3 forms of pain?
Nociceptive, inflammatory and pathological pain
What is nociceptive pain?
Adaptive - an immediate protective response, short lived
What is inflammatory pain?
Adaptive - assists in healing, persists over days, possibly weeks
What is pathological pain?
Maladaptive - no physiological purpose, persists over months, years or even a lifetime
How is acute pain normally managed?
Generally effectively controlled by NSAIDs, paracetamol and in moderate/severe cases the addition of opioids of several classes
Chronic pain can sometimes be managed by a number of alternative classes of drug such as?
Antidepressants
Anticonvulsants
Local anaesthetics
What kind of pain is not managed well by opioids?
Neuropathic pain
How is pain originating from the skin typically described?
Well localised
Pricking, stabbing, burning
How is pain originating from muscle typically described?
Poorly localised
Aching, soreness, tenderness, cramping, stabbing, burning
How is pain originating from viscera typically described?
Poorly localised
Dullness, vagueness, fullness, nausea
Somatosensory pathways often comprise three neurons in series. Where is the cell body location of the 1st order neuron?
Dorsal root ganglia (innervation of limbs, trunk, posterior head) or cranial ganglia (innervation of anterior head)
Somatosensory pathways often comprise three neurons in series. Where is the cell body location of the 2nd order neuron?
Dorsal horn of spinal cord or brainstem nuclei
Somatosensory pathways often comprise three neurons in series. Where is the cell body location of the 3rd order neuron?
Thalamic nuclei
What are nociceptors?
Specific peripheral primary sensory afferent neurons normally activated preferentially by intense stimuli (e.g. thermal, mechanical, chemical) that are noxious
Nociceptors are first order neurons that relay information to 2nd order neurons in the CNS by chemical synaptic transmission
Nociceptive pain is adaptive and high threshold. What does this mean?
Adaptive - an early warning system to detect and minimise contact with damaging stimuli
High threshold - generally provoked only by intense stimuli that active nociceptors