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Flashcards in Control: Pain Deck (16)
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1
Q

What is nociception?

A

The sensory process that provides the signals that trigger pain.
Transduction of nociceptive stimuli occurs in the free nerve endings of unmyelinated ‘C’ fibres & thinly myelinated ‘Ad’ fibres

2
Q

4 important points on types of sensory afferents?

A

1) Large diameter, rapidly conducting afferents (I/II) associated with low threshold mechanoreceptors
2) Small diameter, slow conducting afferents (III/IV) associated with nociceptors & thermoceptors
3) Thermal & mechanical nociceptors have Adelta fibres
4) Polymodal nociceptors have C fibres

3
Q

Features of 1st pain?

A
Fast A-delta fibres
Sharp or prickling
Easily localised
Occurs rapidly 
Short duration
Mechanical or thermal nociceptors
4
Q

Features of 2nd pain?

A
Slow C-fibres
Dull ache, burning
Poorly localised
Slow onset
Persistent
Polymodal nociceptors
5
Q

Where do nociceptive fibres have their cell bodies? What happens after they enter the dorsal horn?

A

Within the dorsal root ganglion.
After terminals enter the dorsal horn, they travel up/down a short distance (1 or 2 spinal segments) within the Zone of Lissauer. Afferent terminals then synapse within the superficial laminae of the dorsal horn.
They synapse with neurons in lamina I & II (substantia gelatinosa)

6
Q

Referred pain of:

a) Bladder
b) Ureter
c) Prostate
d) Appendicitis

A

a) Perineum
b) Lower abdomen & back
c) Lower trunk & legs
d) Navel wall area

7
Q

What excitatory neurotransmitter do pain afferents release?

A

Glutamate

8
Q

What important neuropeptide do synaptic terminals have?

A

Substance P. (most dense in superficial dorsal horn)

9
Q

WHO analgesic ladder?

A
  • ->Aspirin, NSAIDS, Cox-2 inhibitors
  • ->Codein, Tramadol
  • ->Morphine, Fentanyl, Methadone
10
Q

Mechanism of action of non-opioid analgesics? (NSAIDS/ COX-2 inhibitors)

A

Act mainly peripherally (paracetamol has central activity)

11
Q

Mechanism of action of opioid analgesics? (tramadol, codeine, morphine)

A

Act at 2 sites in the spinal cord:
Presynaptically pain signal transmission is reduced.
Postsynaptic membrane is hyperpolarised, decreasing the probability of action potential generation.
-Main eficacy in nociceptive pain.

12
Q

What pain relief would you use in Renal failure?

A

NOT morphine/codeine.

Use fentanyl or oxycodone

13
Q

What are the features of neuropathic pain?

A

Often persistent or recurrent
Associated with sever comorbidity & poor quality of life
(MECHANISM: trauma/amputation etc leads to hyperexcitable spinal cord which leads to expanded hyperexcitable dorsal horn with new inputs)

14
Q

How are Antidepressants (TCAs) used in neuropathic pain therapy?

A

Inhibition of neuronal reuptake of noradrenaline & serotonin.

15
Q

Types of Anticonvulsants used in neuropathic pain therapy?

A

Gabapentin, Pregabalin, Carbamazepine

16
Q

What is used to measure pain quality?

A

McGill Questionaire