Lecture 4 - Pain

Question 1

what areas of the brain interpret pain?

Answer 1

brainstem, midbrain, thalamus and cerebral cortex

Question 2

what is transduction of pain?

Answer 2

process by which a painful stimulus is transformed into a signal that can be carried to the CNA and perceived as pain

Can be targeted by NSAIDs and gabapentinoids

Question 3

what is transmission?

Answer 3

neurotransmitters send pain impulses along axons in dorsal root ganglion – impulse travels to dorsal horn – up spinothalamic tract to thalamus – impulse distributed for interpretation in different parts of brain

can be target for local anesthetic and gabapentinoids which block Substance P (excitatory) at spinal level

Question 4

what is perception of pain?

Answer 4

awareness by somatosensory cortex of brain

targeted by opiods and NMDA receptor antagonist (ketamine)

Question 5

what is modulation of pain?

Answer 5

inhibitory neurotransmitters from brainstem block pain impulse as a defense mechanism (GABA, oxytocin, serotonin, noradrenaline)

targeted by epidurals, nerve blocks and wound infusions

Question 6

why is it good to know what type of pain a patient is experiencing?

Answer 6

to know which nociceptors have been activated

Question 7

what type of pain do A delta fibers cause?

Answer 7

shooting, stabbing and stinging
fibers are large in diameter
located in fingertips/hands

Question 8

what type of pain do C fibers cause?

Answer 8

slow, dull, aching
small in diameter
located in internal organs

Question 9

what are examples of excitatory chemicals?

Answer 9

bradykinin
prostaglandin
glutamate
aspirate
nitric oxide
calccitonin gene related peptide

Question 10

what are examples of inhibitory chemicals?

Answer 10

norepinephrine
serotonin
endorphins
GABA

Question 11

what are a-beta fibers

Answer 11

substantia gelatinosa sends information from a-beta fibers to brain to deal with pain

when rubbing a sore spot this stimulates a-beta fibers so they carry information related to touch whereas a-delta carry info related to pain and temperature

Question 12

what is somatic pain?

Answer 12

pain of connective tissue, muscles or bone

Question 13

what is visceral pain?

Answer 13

damage to internal organs or cavity linings

Question 14

what is referred pain?

Answer 14

moved from localized area to another part of the body

Question 15

what is neuropathic pain?

Answer 15

burning, electric, tingling or shooting pain

Question 16

how can you tell if pain is neuropathic?

Answer 16

Allodynia and hyperalgesia

Question 17

what is allodynia?

Answer 17

pain resulting from a stimulus that ordinarily does no elicit a painful response (light touch)

Question 18

what is hyperalgesia

Answer 18

increased sensitivity to a normally painful stimuli

Question 19

what are the ABCs of pain management?

Answer 19

Ask about pain
Believe patient
Choose pain control that is appropriate
Deliver interventions properly
Empower patients

Question 20

what are the 3 steps of the WHO analgesic ladder?

Answer 20

1. pain = non-opioid and adjuvant
2. pain persisting/increasing = opioid for mild to moderate pain + non-opioid + adjuvant
3. Pain persisting/increasing = opioid for moderate to severe pain + non opioid + adjuvant

Question 21

what is Trigeminal neuralgia?

Answer 21

chronic pain condition that affects the trigeminal or 5th cranial nerve

possibly caused by herpes zoster virus or demylination of nerve

Question 22

what is type one chronic regional pain syndrome?

Answer 22

develops after initiating noxious event
causes spontaneous pain, allodynia and hyperalgesia, odema, abnormalities in skin blood flow

Question 23

what is type two chronic regional pain syndrome?

Answer 23

develops after nerve injury
pain not limited to territory of injured nerve
odema, abnormalities in skin blood flow