Final Pain Flashcards
What are the 3 brain circuits?
Peripheral pain Circuitry
Spinal Pain Circuitry
Brain Pain Circuitry
What are the 2 types of pain?
Acute
Chronic
What is considered “chronic” pain?
Pain lasting > 3 months
What are the 4 types of chronic pain?
Nociceptive
Neuropathic
Visceral
Mixed
What is nociceptive pain?
Related to inflammation/inflammatory condition
What is neuropathic pain?
Neuronal origin (neurogenic)
What is visceral pain?
Pain/pressure around internal organs
Diabetic neuropathy is an example of what type of pain?
Chronic -> Neuropathic -> Peripheral
What is the “fifth vital sign”?
Pain
-considered this
What are the 3 functions of pain?
-Warning system (avoid injury)
-Aid in repair (make area hypersensitive to avoid use of area so tissue can heal)
-Can be maladaptive (inflammation may lead to more damage)
How do we characterize pain?
Temporal features (onset, duration, course, pattern)
Intensity (average, least, worst)
Location
Quality
Pain from inflammation may have what qualities?
Throbbing
Pulsating
Neuropathic pain may have what qualities?
Stabbing
Shooting
Burning
Tingling
Visceral pain may have what quality?
Squeezing
What is opioid induced hyperalgesia?
Chronic opioid use makes pain worse and more pronounced
-This is an adaptive response by the body to opioid treatment
What is referred pain?
Pain that comes from another area of the body but the patient feels it in a different area
(ex: MI pain may extend down arm or in jaw)
What is the relation between pain and mood?
Pain is an EMOTION and impacts mood
*may make the Wong-Baker face rating scale less accurate if child is upset
What is the transmission pathway that pain takes in the periphery?
Periphery -> Spinal Cord -> Central Effect (brain) -> Back to Spinal Cord
The release of which inflammatory mediators at a site of trauma stimulates the afferent neuron to send signals to the spinal cord?
Prostaglandins
Bradykinin
Potassium
In the periphery, what is activated after trauma?
Peripheral Nervous System
What are the 3 groups of receptors in the periphery involved in pain signaling?
Temperature Sensitive
Acid Sensitive
Chemical Irritant Sensitive
What are the 3 temperature sensitive receptors?
Transient receptor potential cation channel (TRP)
TRPV (Vanniloid)
TRPM (Melastatin)
What is the role of the Transient receptor potential cation channel (TRP)?
Conducts Na, K, or Ca
What is sensed by the receptor TRPV (Vanniloid)?
Heat
(and spice/ capsaisan)
What is sensed by the receptor TRPM (Melastatin)
Cold
(also menthol)
What is the acid sensitive receptor in the periphery?
Acid sensing ion channel (ASIC)
What molecule activates the Acid sensing ion channel (ASIC)?
H+
What molecule does the Acid sensing ion channel (ASIC) conduct?
Na+
What are the chemical irritant sensitive receptors in the periphery?
Histamine
Bradykinin
True or False: the reflex upon painful stimuli does not require CNS processing and does not need to go to the brain to occur
True
What channels are important for action potential conduction?
Na+ and K+
(*specifically Na1.8)
Which sodium channel is most important for action potential conductance?
Na 1.8
What neurotransmitter is important in pain conduction?
Glutamate
-in spinal cord
What are teh glutamate receptors?
AMPA (ion channel)
NMDAR (ion channel)
mGluR (metabotropic receptor)
What are the 3 different pain fibers?
A beta fibers
A delta fibers
C-fibers
What pain signals are transduced by A beta fibers?
Non-noxious (not pain producing)
ex: touch, pressure
What pain signals are transduced by A delta fibers?
Pain, Cold
“First Pain” -reflex arc (sends initial feeling to brain)
-sharp, prickly
What pain signals are transduced by C-fibers?
Pain, Temp, Touch, pressure, Itch
(polymodal) -involved with prolonged pain
“Second pain”
-dull, aching (nagging persistent pain)
Does not having a myelin coating make a signal pathway faster or slower?
Slow
Rank the 3 different pain fibers in order of Fastest to Slowest
F:
A beta- fibers (thick myelin coating)
A delta fibers (myelinated but not thick)
C-fibers (unmyelinated)
S:
What is peripheral sensitization?
Repeated stimuli reduce firing threshold
-easier for pain conducting neurons to fire and conduct the painful stimuli
-more heightened pain response
What substance is responsible for peripheral sensitization?
Substance P
(a neuropeptide released upon injury)
What are the 4 functions of substance P?
Vasodilation
Degranulation of mast cells
Release of histamine
Inflammation and prostaglandin release
How do the functions of Substance P contribute to peripheral sensitization?
Increase expression of pain receptors
What leads to neuropathic pain sensitization in the spinal cord?
Change in neuropeptide release
-CGRP and Substance P released
-Chemical and biochemical changes occur on postsynaptic neurons in the spinal cord causing increased sensitivity
**Also increased AMPA and NMDA receptor expression which leads to more sensitivity
-these enhance the excitability of spinal neurons and pain conduction
*Also possibly enhanced sodium channel subtype expression leading to:
–Enhanced cellular excitability
–Generation of ectopic action potentials
Where in the brain is there a high expression of opioid receptors?
In the brain stem along the descending pathway
*note: endogenous opioids stimulate descending inhibition
What is the main opioid receptor expressed in the brain?
Mu opioid receptor
What is the function of the descending pain pathway from the brain?
Modulates both the perception of pain and the signal coming up into the brain to allow you to perceive pain
What is the main opioid receptor targeted by drugs?
Mu opioid receptor
(important in modulating pain pathways, also targeted by endogenous opioids)
What are the actions of mu opioid receptors in the brain?
-Alter mood
-Produce sedation
-Reduce emotional reaction
What are the actions of the mu opioid receptors in the brainstem?
Increase the activity of descending fibers
What are the actions of the mu opioid receptors in the spinal cord?
Inhibit vesicle release
Hyperpolarize the post-synaptic membrane
What are the actions of the mu opioid receptors in the periphery?
Reduce activation of primary afferent
Modulate immune activity
What is the function of the somatosensory cortex (cortex) in processing pain?
Tells you where on the body the pain is coming from
What is the function of the amygdala in processing pain?
Anticipates pain and reacts to perceived threats
What is the role of the prefrontal cortex in processing pain?
Decision making, processes pain and plans actions to reduce the pain
What is the function of the right lateral orbitofrontal cortex in processing pain?
Evaluates sensory stimuli, decides response
*Particularly used if fear is involved
What is the function of the nucleus accumbens in processing pain?
Releases dopamine and serotonin
**this is the area associated with pleasure upon opioid use and addiction
What questions would you want to ask to subjectively assess a patient’s pain?
PQRSTU
Precipitating factors (what makes better/worse)
Quality (stabbing, stinging, burning)
Region of pain location
Severity
Time-related nature (worse at certain time of day?)
U: impact of pain on yoU
What objective information should we assess regarding pain?
Behavioral Changes
Physiological Changes
(sweating, pallor, tachycardia, dilated pupil, etc)
What is acute pain?
Pain lasting < 3 months
What is an example of acute pain?
Nociceptive pain
(tissue)
What is an example of chronic pain?
Neuropathic pain
(nerve)
What are the goals of therapy with pain treatment?
Correct underlying cause of pain
Minimize pain and symptoms (may not be able to be pain free, be realistic)
Improve QOL
Limit side effects
What is the step-wise approach for treating nonmalignant pain created by the WHO?
Step 1: Non-opioid + or - Adjuvant analgesic
Step 2: Opioid for mild-moderate pain + Non-opioid + or - Adjuvant Analgesic
Step 3: Opioid for moderate-severe pain + Non-opioid + or - Adjuvant Analgesic
When do we go to the next step in pain treatment?
If pain is persisting or increasing
When do we step down in pain treatment?
If pain is resolving or toxicity occurs
