PAIN- Ballyk lecture

Question 1

what is algesia?

Answer 1

Sensitivity to pain

Question 2

what is analgesia?

Answer 2

Absence of sensitivity to pain

Question 3

What is hyper/hypoalgesia?

Answer 3

Increased or decreased sensitivity to pain

Question 4

what is allodynia?

Answer 4

Pain sensation elicited by a normal non painful stimulus

Question 5

What is dysesthesia?

Answer 5

Abnormal unpleasant sensation

Question 6

What is nociceptive pain?

Answer 6

Normal pain functioning system

1. Tissue damage
2. Inflammatory pain

Question 7

What is neuropathic pain?

Answer 7

Pain-reporting system is malfunctioning - perceive pain but no damage

1. post-herpetic neuralgia
2. central pain
3. phantom limb pain
4. diabetic neuropathy

Question 8

What are the three types of nociceptors?

Answer 8

1. Thermal (Adelta)
2. Mechanical (A delta)
3. Polymodal (C fibers)

Question 9

Describe characteristics of thermal Nociceptors

Answer 9

1. Respond to >45 and <5 degree temps
2. Adelta fibers
3. Fast pain (well-localized, not distressing)
4. part of cutaneous nerve

Question 10

Describe characteristics of Mechanical nociceptors

Answer 10

1. Respond to intense pressure, nociceptive mechanical stimulus, pinch, pin prick
2. HIGH threshold mechanoreceptors
3. Adelta

Question 11

Describe characteristics of polymodal nociceptors

Answer 11

1. respond to mechanical, thermal or chemical stimuli
2. DIFFUSE pain not well-localized, aching burning, SLOW Pain, distressing
3. C fibers

Question 12

What 2 things happen when a noxious stimulus is applied?

Answer 12

1. Withdrawal reflex

2. Perception of pain - (post central gyrus)

Question 13

2 mechanisms that inflammation results from

Answer 13

1. Neurogenic inflammation (axon reflex)

2. Tissue damage

Question 14

During the inflammatory event are pain signals sent to CNS?

Answer 14

YES, and nociceptors are sensitized

Question 15

What are 3 things characterize inflammation?

Answer 15

1. Redness
2. swelling
3. warmth

Question 16

Neurogenic inflammation (axon reflex) characterized by

Answer 16

1. C fiber transmit signals
2. CGRP and Substance P are released from peripheral nerve
3. change in blood vessels
4. Mast cells release histamine
5. platelets release 5-HT - serotonin

Question 17

What are the effects on blood vessels after neurogenic inflammation?

Answer 17

1. Vasodilate
2. Increase permeability - plasma extravasation
3. Release bradykinin -

Question 18

What 3 things are released during an axon reflex that ACTIVATE nociceptors?

Answer 18

ALL ACTIVATE NOCICEPTORS

1. Histamine
2. Serotonin (platelets)
3. Bradykinin (plasma)

Question 19

What 3 things are released during an axon reflex FROM DAMAGED CELLS? SENSITIZE NOCICEPTORS

Answer 19

1. K+ - sensitizes nociceptors
2. Prostaglandins -
3. Leukotrienes

Question 20

What is released from the axon?

Answer 20

Substance P - also sensitizes

Question 21

What does sensitization do?

Answer 21

Decreases activation threshold

Question 22

Where does primary hyperalgesia occur?

Answer 22

In the skin region that is damaged

Question 23

where does secondary hyperalgesia occur?

Answer 23

Adjacent region of the skin that was not damaged

Question 24

What is mechanical hyperalgesia?

Answer 24

hyperalgesia to a mechanical stimulus that would not normally be painful

Question 25

What is thermal hyperalgesia?

Answer 25

Hyperalgesia to a temperature that would not normally produce pain

Question 26

What is the pain we feel due to?

Answer 26

sensitization of C fibbers by prostaglandins

Question 27

3 effects of PGE2

Answer 27

1. has no effect on its own 2. enhances responses to Bradykinin 3. produced from arachidonic acid by COX

Question 28

Pain due to tissue damage is decreased by NSAIDs how?

Answer 28

1. Analgesic effects 2. Antipyretic effects 3. anti-inflammatory effects

Question 29

How do NSAIDs work?

Answer 29

Block COX, so block PGE2 synthesis

Question 30

4 examples of NSAIDs

Answer 30

1. ibuprofen 2. indomethacin 3. Naproxen 4. Aspirin

Question 31

What are the two ways in which inputs are integrated in the dorsal horn in nociception?

Answer 31

1. Referred pain (convergent afferents from viscera) | 2. Gate-control theory (inhibition from touch afferents)

Question 32

How does referred pain work?

Answer 32

First order sensory neurone from 1) body wall 2) viscera (afferents) converge onto second order spinal neurons!

Question 33

How does inhibition from touch afferents work?

Answer 33

1) First order neurone (C-fiber or Adelta pain fiber) ACTIVATES/OPENS the gate to STT 2) Abeta fiber activates inhibitory interneurons - collaterals, inhibit SECOND order neuron cLOSE the gate

Question 34

What is the basis of the transcutaneous electrical stimulation for pain relief?

Answer 34

Inhibition from touch afferents

Question 35

What is the function of the periaqueductal Grey Matter?

Answer 35

1) descending input to the dorsal horns | 2) Release of enkephalins, endogenous opioids from dorsal horn interneurons

Question 36

Enkephalins act on specific opioid receptors to inhibit pain 2 ways...

Answer 36

1) Inhibit NT release from the FIRST ORDER afferent nerve terminal 2) hyper polarize the post-synaptic SECOND order neurons

Question 37

How do exogenous opioids act?

Answer 37

1. Inhibit pain transmutation by binding.activating opioid receptors in first order and second order dendrite/cell body

Question 38

What is responsible for the emotional response to nociception?

Answer 38

1. SECOND order neurons in SL synapse onto 2. THIRD order neurons in thalamus (RETIC?) project to 3. Cingulate gyrus NOT POST CENTRAL GYRUS

Question 39

Does neuropathic pain activate nociceptors?

Answer 39

NO

Question 40

When does neuropathic pain occur?

Answer 40

Damage to nerves/neural tissue in PNS, CNS (by injury or diseasE)

Question 41

What 3 things may be involved with neuropathic pain?

Answer 41

1. Allodynias 2. Dysesthesias 3. Hyper algesias

Question 42

Give examples of neuropathic pain

Answer 42

1. Peripheral damage a) Diabetic neuropathy b) Trigeminal neuralgia c) Post-herpetic neuralgia 2. CNS damage a) Post-stroke pain b) brachial plexus avulsion pain c) spinal injury pain