Lecture 7 - Pain (2/4) Flashcards
Things like touch, vibration, coolness or warmth are sensed by ____ threshold receptors
low threshold receptors
high threshold receptors sense stimuli such as
noxious heat or cold, pinch, crush, laceration, chemicals)
what are the 2 main types of high-threshold afferents we discuss
- A-delta fibres
- C-polymodal (CPM)
Which highthreshold fibres are myelinated and involved in sensing quick-sharp and localized pain?
A-delta fibres
C polymodal (CPM) fibres are responsible for what type of pain due to the fact that they are unmyelinated?
dull ache, onsets slower after initial injury
what is this image demonstrating?
that free nerve endings express a number of receptor terminals that respond to many things including noxious temp., chemical irritation or pressure. Also, the receptors present on each nerve ending vary.
what about an action potential changes in the presence of noxious stimuli resulting in the body becoming more sensitive? (2)
- the resting membrane potential might increase and activation threshold may decrease
- the duration of the refractory period may decrease
what changes about an action potential increase the sensitization of a cell?
a. amplitude
b. frequency
b. frequency
Label parts A,B,C and D
a. myelinated axon
b. Schwann cell
c. fascicle
d. peripheral nerve
what are the two secondary neurons we discussed?
- Nociceptive specific
- Wide Dynamic range (WDR)
label the missing parts
A. lateral spinothalamic tract
B. Dorsal root ganglion
what 3 factors affect the input of a A-delta or CPM nerve to a second-order neuron? (3)
- descending input from CNS
- A-beta fibres that synapse onto an interneuron (substantia gelatanosa) to create an inhibitory response as found in gate control theory.
- electrical impulses through electrode stimulation
what is the proposed role of glial cells in pain?
believe they have receptors for substance P and release NT of their own which might be picked up by WDR and stimulate the pain response. Because there are so many - can lead to chronic pain or pain moving to different areas outside of the injury site.
Allodynia
pain due to a stimulus that does not normally provoke pain
what causes allodynia?
convergence of signals from nociceptors and mechanoreceptors onto the lamina of the dorsal horn. when substance p is released due to pain sensation it can make other receptors more sensitive resulting in the feeling of pain with touch, etc.
why is the neuromatrix model important in terms of treatment as physiotherapists?
demonstrates their are a number of different areas for and modes of treatment that may work to relieve patients symptoms
what is this picture demonstrating in terms of chronic pain?
with chronic pain there is a shift In the neuroplasticity of the brain leading to pain sensation felt in many areas of the brain and rewiring’s taking control.
can the brain of an individual with chronic pain be reversed back to a healthy brain threw rehabilitation? what example did we discuss in class?
yes effects of chronic pain in the brain can be reversed.
look at a study of 2pt discrimination of the index finger in people with and without complex regional pain syndrome
what are the 5 pain mechanism classifications?
- nociceptive (physiologic)
- neuropathic (non-physiological)
- central (nociplastic)
- emotional
- Visceral
pain that is primarily driven by tissue stimuli that is intense enough to cause potential or actual damage is…
nociceptive
which pain mechanism is orthodromic only?
A. Nociceptive
B. Neuropathic
A. Nociceptive
neuropathic also has action potentials that travel antidromically
what are 3 types of stimuli sensed by nociceptive receptors?
1) mechanical (cut, crush)
2) thermal (burning, freezing)
3) chemical (inflammatory)
clinical indicators such as:
predictable, consistent, associated with movement or pressure, tissue-based abnormality, and responds to NSAIDS are common to which type of pain mechanism?
nociceptive
some clinical indicators of neuropathic pain include:
must be related to nerve pathology, can have unpredictable and inconsistent association with movement, localized to nerve distribution, strange symptoms, not responsive to NSAIDS
some clinical indicators of nociplastic pain include:
usually more chronic, poor association with movement, no clear association with tissue abnormality, might be amendable to opioids but not NSAIDS
the clinical indicators such as difficult to locate at time, pain usually related to negative emotions, no clear association with movement or tissue abnormalities, no response to NSAIDS is said to be which pain mechanism?
emotional
what are some clinical indicators of visceral pain
poorly localized, not normally related to movement but may be worse in certain postures depending on the organ, often occurs with other symptoms, no response to NSAIDS or mechanical therapies
pain that is primarily driven by action potentials arising from a damaged nerve is
neuropathic (non-physiological)
pain that is primarily driven by abnormal CNS activity is:
central (nociplastic)
pain that is primarily driven by strong negative emotions is:
emotional
pain that is primarily driven by stimuli arising from the viscera more likely due to inflammation, chemical irritation or ischemia is:
visceral
what is his preferred definition of pain duration?
it’s not the duration of pain that differentiates acute from chronic but rather the inability of the body to restore homeostasis.
time frame of acute pain
3-6 weeks
time frame of subacute pain
3-6weeks to 3-6months post injury
time frame of chronic pain
pain lasting 3-6months after onset
what type of pain duration is seen as adaptive or protective?
acute
what type of pain duration is seen as non-adaptive or non-protective
chronic
