Pain Flashcards
pain
most common symptom that brings a patient to a doctor. function is to protect tissue by detecting, localizing, and identifying tissue-damaging processes.
acute pain
1 week or less
chronic pain
pain for at least 6 months
chronic regional pain syndrome
limb is cold, red, muscle wasting, nail changes
mechanism of endorphin activity in CNS
inhibiting GABA, thus disinhibiting dopamine. receptors in the descending pain circuit
mechanism of endorphin activity in PNS
primary afferent neurons, peripheral sensory nerve fibers, dorsal root ganglia. inhibition of substance P (pain driver) and other tachykinin release
mechanisms of release
peripheral: mediated by stress and ACTH co-release. Central: involves innervation of the hypothalamus, midbrain, and rostral medulla
what does blocking glutamate do?
since glutamate upregulates pain system, blocking it helps prevent hyperalgesia.
what type of pain are NSAIDs used for?
inflammatory.
what are safer, NSAIDs or opioids?
NSAIDs! much less side effects.
what are the function of antiepileptic drugs?
lowering a neuron’s ability to fire, by hyperpolarization or disallowing depolarization
what happens in full pain response?
significant Ca and Na influx noted, leading to acute pain since the nerves are firing
what happens in chronic pain?
system goes awry, gets stuck. leads to central sensitization and excessive pain. the system keeps firing, and pain is from Na, Ca, and now glutamate release.
what three things can you block to stop neuropathic pain?
Glu, Na channel, Ca channel
AED side effects
generally may cause sedation, psychomotor/cognitive impairment, ataxia, tremor
the role of norepinephrine and antidepressants in stopping pain
add norepi reuptake inhibition to strengthen the descending pathway, and it impinges upon a GABA interneuron system that dampens the ability of ascending pain fibers to fire and pain symptoms may resolve
normal NE/GABA system
normal amounts of NE stimulate GABA, which inhibits pain
Abnormal NE/GABA system
low amounts of NE can’t activate GABA, allowing pain transmission
what antidepressants are used for pain?
duloxetine and milnacipran are SNRIs. they cause serotonin and norepi side effects. Amitriptyline is a TCA that has a lot of side effects and Na+ channel blockade.
interventional approaches
nerve blocks, facet injection, epidural, radio frequency ablation, dorsal column stimulator, intrathecal pain pump, acupuncture, TENS, physical therapy, aqua therapy, massage therapy, cognitive behavioral therapy
