Pain Pathways Flashcards
an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage
pain
what two things can influence clinical decision making and patient outcomes for each individual patient
pain and pain tolerance
what is the 5th vital sign
pain
what affects more people than DM, heart disease and cancer combined
chronic pain
what are the most common sources of pain
spinal pain, HA, arthritis
what can pain impact
- pain receptors do not follow predictable rules
- pain can lead to changes in autonomic function (increaed HR, BP, RR)
- pain impacts your affect
- pain impacts motivation
pain results from direct nociceptive stimulation and triggers inflammatory response via release of substance P and other chemical mediators at the site of tissue injury
physiologic pain (nociceptive)
pain results from direct injury to CNS/PNS structures and associated with incomplete or maladaptive regeneration of axons following injury in PNS and CNS structures
neuropathic pain
examples of neuropathic pain
DM neuropathy, phantom pain, thalamic pain
what are the 6 steps in nociceptive process
transduction
inflammation
conduction
transmission
modulation
perception
activated by intense pressure on the skin
mechanical nociceptors
what fibers do mechanical nociceptors travel on
A delta
activated by extreme temperatures
temperature nociceptors
what fibers do thermal nociceptors travel on
A delta
activated by intense mechanical, thermal, or chemical stimuli
chemically sensitive and polymodal nociceptors
what do chemically sensitive and polymodal nociceptors travel via
C
what are the 2 types of afferents that allow for conduction from the nociceptor to the spinal cord
afferent a delta to DRG (immediate pain)
afferent C fibers to DRB (slow pain)
small myelinated fibers for fast pain response, sends noxious information from skin and mucous membranes
A deltas
acute, sharp, well localized pain
a deltas
small unmyelinated fibers for slow pain and send noxious information from muscles, tendons, digestive tract, skin and heart
C fibers
chronic pain, dull, burning, aching, poorly localized or referred pain
C fibers
what is triggered to be released when tissue to damaged to trigger an inflammatory response and what is an example
cytokines - prostaglandins
sensory nerve fibers (primary afferent) receive the signal and carry it to the info to the dorsal horn of the spinal cord via the
1st order neuron
a delta and C fibers for mechanical/thermal pain go to which laminar level
1 and 2
A beta and C fibers for mechanical and pain stimulus from muscle, viscera and skin go to which laminar levels
4 and 5
sensory information after passing the DRG will synapse to what and cross over to the opposite ALS
2nd order neuron
which afferent spinal tract carries pain
ALS
what 2 types of cell bodies allow for transmission of the afferent to the gray dorsal horn
nonspecific/wide dynamic range neurons (WDR) and specific neurons
where are cells bodies for nonspecific/wide dynamic range neurons located and which fibers do information travel via
lamina V
A beta and C afferents
nonspecific wide dynamic range neurons area activated by what
mechanical and nociceptive stimuli from viscera, muscle, and skin
axons from the nonspecific wide dynamic range neurons form which tract
paleospinaothalamic tract (slow pain)
specific neuron cells bodies are located in which lamina and receive information via which afferents
lamina I and II
A delta and C afferents
specific neurons are activated by
mechanical/thermal nociceptive pain
axons of specific neurons form which tract
neospinothalamic tract (fast pain)
what are the main neurotransmitters associated with pain messaging in the spinal cord
glutamate and substance P
what binds with AMPA type receptors that are for fast excitatory post-synaptic potentials (EPSP)
glutamate
what is released from C afferents onto lamina I and II eliciting slow EPSPs
substance P
neurotransmitters that are inhibitory and mediate analgesia and reduction of hyperalgesia
adenosine and GABA
what neurotransmitter is a second messenger enzyme involved in hyperalgesia
protein kinase A
endorphins, enkephalins, serotonin, and norepinephrine for central mediation of pain
supraspinal descending afferents
participate in receptor expression and clearing away of neurotransmitters that remain in the synaptic cleft
glial cells
which tract mediates slow pain
paleospinalthalamic (paramedial ascending system)
what type of pain are associated with paleospinalthalamic tract
- strong emotional response (annoying pain)
- not easily localized and difficult to rate intensity
what fibers carry pain from paleospinalthalamic tract
C
travels to reticular formation, parafasiculus, and then centromedian thalamus and then to several other cortical areas
paleospinalthalamic tract
mediates crude touch, temperature, and fast pain
neospinothalamic
what are the two components of ALS for the transmission of pain
paleospinalthalamic and neospinothalamic tracts
mediates pain that is easily located and rated intensely, but is short lasting
neospinothalamic tract
how to test neospinothalamic tract
pinprick on sharp dull test
what fibers carry information from neospinothalamic tract to the cord
A delta
travels to ventral posterolateral (VPL) nucleus of thalamus and then to the primary somatosensory cortex
neospinothalamic tract
neospinothalamic and paleospinothalamic axons travel together in the
ALS
in the ALS, dorsolateral is associate with and ventromedial is associated with
Dorsal - LE
Ventral - UE
in the ALS, dorsolateral is associate with and ventromedial is associated with
Dorsal - LE
Ventral - UE
in the ALS, dorsolateral is associate with and ventromedial is associated with
Dorsal - LE
Ventral - UE
in the brainstem, which tract are on the lateral edge between the inferior olivary complex and spinal trigeminal complex
neospinothalic
what does the neospinothalamic tract merge with to ascend to the VPM/VPL thalamus
trigeminal nucleus
which tract axons give off branches to reticular formation which produces arousal response to painful stimuli and stays medial
paleospinothalamic tract
which tract has axons that arranged somato-tropically
neospinothalamic
no somatotropic arrangement and courses medially at the brainstem
paleospinothalamic axons
what are the multiple tracts that make up the paleospinothalamic tract
spinoreticular tract
spinomesencephalic tract
spinohypothamic tract
spinomeotional tract
at the level of the medullar and pons via raphe nuclei and responsible for arousal/attention/sleep wake cycles (slow pain alters sleep)
spinoreticular tract
goes to periaqueductal gray at midbrain to superior colliculus and periaqueductal gray (PAG); has superior colliculus and PAG
spinomesencephalic tract
what part of the spinomesenchalic tract turns eyes toward the pain location
superior colliculus
what part of spinomesencephalic tract activates descending pathway to inhibit pain
PAG
travels to the hypothalamus and activates autonoimic and endocrine responses to pain
spinohypothalamic tract
located at VPM which projects to dorsolateral prefrontal cortex, anterior cingulate gyrus, and amygdala and activates in controlling emotional, sensory and motor response to pain
spinoemotional tract
thalamocortical pathways carry nociceptive information to the cortex which is the _____, a complex network of synaptic links
pain neuromatrix
the VPL to where responds to intensity and location of pain from the contralateral body and face
Brodmann’s area 1 (primary somatosensory cortex)
the VOL to where recongnizes and signals eyes/head turn toward pain stimulus, learns about and remembers painful events
secondary primary somatosensory area in insula (SII)
from the palospinothalmic and trigeminothalamic pathways to the VPM to what provides affect, motivation toward, and response selection for nociceptive stimuli
cingulate gyrus
endogenous opioids bind to peripheral afferents receptors to limit nociceptive response
level 1 periphery
local interneurons release encephalin/dynorphin via counterirritant effect, the gating mechanism
level 2 dorsal horn
descending cortical input or endogenous opioids bind to receptors; narcotic bind to these same receptors, serotonin and norephinephrine
level 3 fast acting descending from PAG, medulla, locus coeruleus
periventricular gray and pituitary gland release beta-endorphine, and adrenal medulla; low frequency TENS, rhythimic activities, stress mediated
level 4 hormonal system
emotional aspects of pain; placebo, distractions, excitement and also activated by opiate drugs
level 5 amygdala and cortex
two types of cortical modulation of pain
descending cortical pain modulation and ascending cortical pain modulation
descending cortical pain modulated comes from ____ and ___ and terminated on _____ in midbrain
cortex
hypothalamus
PAG
descending cortical pain modulation also have projections from _____ in the brainstem to ______ using noradrenergic neurotransmitters
locus coeruleus
dorsal horn
ascending cortical pain modulation occurs bc neurons in the ______ pathway have receptors that bind with interneurons in the dorsal horn that trigger the release of enkephalin or dynorphin inhibiting 1st and 2nd order neurons
paleospinothalamic
cortical pain responses is a _____ regulation
top down
what does cortical pain response depend on
psychologic, physiologic, social and genetic factors
during cortical pain response, what determines response to either inhibit afferent nociceptive input or amplify afferent nociceptive input
pain neuromatrix
neurons in the PAS pathway have receptors that are sensitive to and will bind with
endorphins
modulate pain signals by blocking signal to inhibit release of Ca++ into presynaptic terminal of DRG to decrease neurotransmitters or by opening K+ channels in post synaptic membrane to hyperpolarize to inhibit action potentials of 2nd order neurons
endorphins
what can activate descending opioid system without noxious stimuli
endorphins
3 classes of endorphines
beta-endorphin, met-enkephalin, dynorphin
what is the way pain is modulated locally in the periphery
gate control theory
what located in the spinal cord may modulate the transmission of pain signal in the gate control theory
interneurons
pain modulation in the gate control theory is only achieved if _____ fibers are activated bc they are able to excite interneurons in lamina V to inhibit pain messsage by closing the gate to both pre and post synaptic neurons
A beta
what can be used in the clinic to apply gate control theory
TENS, exercise, trigger point massage, acupuncture
what are the 3 ways the dorsal horn processes nociceptive input
normal
anticociceptive - suppressed
pronociceptive
what are the two types of pronociception
- sensitized - hyperalgesia –> heightened response to less stimuli
- reorganized - allodynia –> changes to dorsal horn
what can occur with sensitization and reorganization
neuropathic pain
occurs when receptors become increasingly responsive or the threshold for a noxious stimulus decreases
hyperalgesia
sustained inflammatory response during hyperalgesia occurs due to
- release of histamine and serotonin at site of injury by mast cells
- prostaglandins released by fibroblasts
- indirectly by interleukin-1, bradykinin, substance p
altered processing by WDR neurons in lamina V of non-nociceptive incoming information on A-beta afferents
allodynia
if input by C fibers is intense and there is an increased of glutamate and substance P released in the dorsal horn, WDR neurons are _____
depolarized
reduces pain by increasing local blood circulation to flush out inflammatory irritants at the site of tissue damage and also stimulated A beta resulting in gate control theory
touch and massage
high frequency TENS stimulated which fibers and low frequency TENS stimulates which fibers
A delta/A beta - gate control theory
C fibers - activates descending inhibitory pathway
how does acupuncture work to decrease pain
activation of descending central modulation
how long do you have to have pain for it to be considered chronic
> 3 months
neuropathic pain is produced by what 3 main mechanisms
central sensitization
ectopic foci
ephaptic transmission
what is associated with an injury to the somatosensory system and what are examples
neuropathic pain
phantom limb, thalamic pain syndrome, complex regional pain syndromes
during phantom limb pain, the brain perceives that the limb is still present until ______ is complete
cortical reorganization
pain following CVA or thalamus lesion on the ventrobasal complex; described as unremitting pain, aching, boring, gnawing, burning, and/or crushing
thalamic pain syndrome
occurs following a lesion or series of traumas; results in abnormal sensory changes, altered blood flow, excessive sweating due to sympathetic denervation; pain described as severe, persistent or burning
complex regional pain syndrome CRPS
reflex sympathetic dystrophy - trauma to distal extremity
CRPS 1
causalgia - trauma to peripheral N
CRPS 2
most common HA that is induced by stress, strain and/or pressure on face, neck and scalp muscles
leads to poor concentration, visual disturbances, tinnitus, dizziness, clumsinnes, TTP, sleep disorders
tension HA
more common in young M; induced by stress, emotional trauma, allergies, alcohol, or high altitudes
throbbing pain behind nose or one eye, usually due to vasodilation of one external carotid A, eye may water and skin may be red
cluster HA
what are the 4 phases of migraines
prodromal
aura
headache
postdrome
premonition that migraine is coming: euphoria, depression, irritable, food cravings, constipation, neck stiffness, yawning
prodromal
visual disturbance that develops 5-20 minutes and last less than 1 hour and is due to cortical spreading depression
aura phase
what is the primary source of intracranial pain in migraines and what N innervates this
dura matter
trigeminal N
what are examples of ablative techniques
rhizotomu, sympathectomy, cordotomy
destruction of dorsal root
rhizotomy
disruption/destruction/removal of sympathetic chain
sympathectomy
disruption/destruction of spinal cord segment
cordotomy
