Chapter 6: Pain Modulation Flashcards
what is pain
unpleasant sensory and emotional experience that is associated with actual or potential tissue damage
-duality based on physiological or psychological experience
function of pain
- warning for withdrawal
- alerts that something is wrong
- protective function (spasm)
goals pain treatment
- resolve underlying pathology causing pain
- modify pt perception of pain to allow participation
- allow pt to maximize functional abilities
categories of pain: nociceptive (somatic)
- activation of nociceptors found in most body tissue
- respond to mechanical and chemical stimuli
- found in skin, joint, mucles
- caused by injury, disease, surgical intervention
- “normal pain”
- treated with electrophysical agents (EPA)
categories of pain: nociceptive (visceral)
activation of nociceptors found in viscera
- referred
- diffuse and poorly localized
- specificity: not all viscera are sensative to pain
- EPA not effective
categories of Pain: neuropathic
Peripheral: disease associated with peripheral nerves (EPA treated)
- Central: due to pathological functioning of CNS
- -often delayed as in stroke, MS, parkinson’s disease
- -seldom treated EPAs
Categories: psychogenic
non organic source
-assocaited with emotional, cognitive, behavioral responses
carcinogenic pain
- caused by cancerous pathology
- EPA not effective
types of pain
- acute
- chronic
- referred
- radicular
acute
-perception of pain is combination of unpleasant sensations with emotional and psychological reactions, but in response to noxious stimulus provocted by acute injury
acute pain
- tmie limited
- mediated through rapidly conducting pathways
- assocaited with increased sympathetic nervous system activity
- intensity: related to extent of tissue damage
- location: well organized and defined
- duration: as long as noxious stimulus persists
- serves protective function
- may impair function
treatment acute
- facilitate resolution of underlying disorder
- reduce inflammation
- modify transmission of pain from periphery to CNS
chronic pain
continuous, long term pain
-more than 12 weeks
chronic pain
duration: several months or years
symptoms: simliar to original symptoms
history of many treatment failures
-history many medications tried
-continued use of analgesics and tranquilizers despite no long term effects
-intensirty: unbearable or incapacitating
-often seeking right treatment to cure pain
chronic pain psychosocial changes
- ex
- depression
- disturbed sleep
- decreased energy
- altered moods
- etc
chronic pain result of
result form changes in sympathetic NS, adrenal activity, reduced production of endogenous opioids, or sensitization of primary afferents
-increased sensitivity to both noxious (hyperalgesia) and non-noxious (allodynia) stimuli
hyperalgesia
increase in perception of pain due to stimulus thought to be painful before, but is more painful now
allodynia
-pain response when a stimulus which was previously none painful is now presented as painful
referred pain
felt at location distant from its source
- from nerve to area of innervation
- from one area to another derived from same dermatome
- from one area to another derived from same embrionic segment
- peripheral nerve pathways from different areas converge on same area of spinal cord
- =synapse with same second order neurons to ascend to cerebral cortex
example referred pain
- pain referred from diaphragm to tip of shoulder-both areas initially develop in the neck region during embryonic development
- both have efferent innervation from phrenic nerve
- both have afferent innervation to second to forth level of C-spine
radicular pain
- originating from irritated nerve root
- follows dermatomal reference
danger alarm system
- transduction-danger receptros
- peripheral transmission
- modulation
- central transmission
- perception
- pain control theories
transduction
- sensors: danger receptors:
- in walls and at ends of neurons
- convey info to spinal cord
- can be specialized:
- mechanical
- chemical
- temp
how does it work
- respond to stimuli by opening, allow (+) particles in, sets off action potential
- chemicals can open or shut: pain medication closes sensor (no transmission to spinal cord), bee sting opens receptor
- recycled every few days, environment determines number and type of sensor
sensors rate of production
- generally stable
- can change sensitivity of neuron if change rate of sensor receptor
nociceptor
- responds to all manner stimuli
- enough activated (opened), a danger message sent to spinal cord
nociceptor def:
- free nerve endings involved in danger detection
- in skin=cutaneous danger
- in tendons and joints=somatic danger
- in body organs=visceral danger
- have high activation threshold, pain threshold vs tolerance
nociception
perception of danger
peripheral transmission
-afferent nerve pathway
perpheral nerve afferent fibers
- A beta fibers: 6-12 um diameter myelinated transmit impulses at >30 m/sec
- A delta fibers-
