Sympathetic Pain 2

Question 1

pathophysiology of CRPS: 3 characteristics?

Answer 1

central sensitization (increased excitability + spont activity in dorsal horn of SC). altered function of descending pain control pathways from limbic structures. pain worsened by stress.

Question 2

CRPS pathophysl: interaction between?

Answer 2

must be an interaction between sympathetic and sensory systems. not normally present, but injury causes sprouting of perivascular sympathetic nerves

Question 3

CRPS: injury causes sprouting?

Answer 3

perivascular sympathetic nerves sprout into neuroma at sight of injury + dorsal root ganglia

Question 4

CRPS: sensory nerves after injury express what receptors?

Answer 4

ectopic alpha 2 adrenoreceptors - will be excited by NA from sympathetic nerves

Question 5

stimulate symp nerve, record sensory nerve activity: what do you see? after phentolamine?

Answer 5

see response both before and after crushing by neuroma. phentolamine = no more response

Question 6

after nerve injury, DRG neurons are responsive?

Answer 6

responsive to NA (before adding NA = no effect, now adding NA = nerve is more excited)

Question 7

after injury: calcium channel currents in DRG neuron?

Answer 7

calcium channel currents are more effectively inhibited by NA

Question 8

CRPS: increased excitability is due to?

Answer 8

attenuation of calcium sensitive K+ conductances following reduced Ca influx. less K+ activity = less hyperpol = cell more excitable