Pain

Question 1

Nocicpetion

Answer 1

Sensory process that provides the signals that trigger pain

Question 2

Pain

Answer 2

Feeling/perception of irritating, sore, stinging, aching, throbbing, miserable/unbearable sensations from a part of the body

Question 3

Congenital analgesia

Answer 3

Don’t sweat, feel no internal/external pain, large scars

Question 4

Nociceptors found in

Answer 4

Periphery as simple free nerve endings, terminate as naked, unmyelinated endings in dermis

Question 5

Normal sensory receptors found in

Answer 5

Cell body in dorsal root ganglion

Question 6

Tissue damage and inflammation leads to

Answer 6

Release of substances (prostaglandins, bradykinin, histamine) - sensitise peripheral nocicpetors and induce hyperalgesia

Question 7

Types of nociceptor

Answer 7

Transduction of nociceptive stimuli occur at free endings of unmyelinated ‘C’ fibres and thinly myelinated ‘Ad’ fibres

Polymodal/only respond to 1

Question 8

Physiological basis of nociceptive pain

Answer 8

Activation of peripheral nociceptors, transmission of impulses via A-delta and C sensory afferents to DH, projection to brain via ascending pathways > avoidance, emotion, withdrawal

Question 9

Transcutaneous nerve recording in human (microneurography)

Answer 9

1. Thermal stimuli applied to receptive field of cutaneous thermoreceptor and nociceptor
2. Record afferent firing to response to incremental temperatures
3. Graph plotting afferent firing frequency vs temp

Question 10

Dissociated sensory loss/Brown-Sequard syndrome

Answer 10

Unilateral spinal lesion, loss of touch, pressure, vibration and proprioception on same side below lesion, pain opposite side

Question 11

Phantom pain

Answer 11

Pain and touch sensations with no sensory inputs

Question 12

Endogenous analgesia/pain modulation

Answer 12

Sensory inputs without pain sensations

Question 13

Hyperalgesia

Answer 13

Increased pain, tissue that has already been damaged/inflamed is extra sensitive (a reduced threshold for pain, increased intensity of painful stimuli, spontaneous pain)

Question 14

Allodynia

Answer 14

Touch-evoked pain

Question 15

Acute pain

Answer 15

Trauma/injury, resolves with healing of underlying injury, protective function, assists wound repair

Question 16

Chronic pain

Answer 16

Persists beyond normal time of healing, 3-6 months beyond onset, tissue damage, not protective, considerable suffering

Question 17

Nociceptive pain

Answer 17

Tissue damage and painful stimuli, regulated by opioidergic system

Question 18

Chronic nociceptive pain

Answer 18

Persists > neuropathic and mixed pain

Question 19

Benefits of acute pain

Answer 19

Trauma response, protective (avoid further damage)

Question 20

Adverse acute pain

Answer 20

Humanitarian, CV stress, resp compromise, hypercoagulation

Question 21

Factors associated with changes in pain perception

Answer 21

Anxiety, depressed, gender, circadian variation, climate

Question 22

WHO analgesia ladder

Answer 22

1 - morphine, fentanyl, hydromorphone, buprenorphine, methadone
2 - Codeine, dihydrocodeine, tramadol
3 - aspirin, NSAIDs, COX-2-inhibitor, acetaminophen

Question 23

Opioids

Answer 23

• Presynaptically pain signal transmission

- Postsynaptic membrane hyperpolarised, decreasing probably of AP generation

Question 24

Non-opioid analegsics - NSAIDS

Answer 24

• Act peripherally
• Act on nociceptive pain
• Inhibit cyclooxygenase, prostaglandin synthesis decreases

Question 25

Side effects of NSAIDs

Answer 25

GI irritation/bleeding, renal toxicity, CV (cox-2)

Question 26

Non-opioid analegsics - paracetamol

Answer 26

- Acts centrally - Analgesic and antipyretic effects - No anti-inflammatory action - Inhibition of central prostaglandin synthesis

Question 27

Paracetamol side effects

Answer 27

Toxic liver damage

Question 28

Examples of weak opiods

Answer 28

Tramadol and codeine

Question 29

Examples of strong opiods

Answer 29

Morphine and oxycodone

Question 30

Efficacy of opiods

Answer 30

Nociceptive pain, less effective in chronic, partially in neuropathic pain

Question 31

Mode of action of opiods

Answer 31

Activate endogenous analgesic system, stimulate receptors in limbic system eliminated subjective feeling of pain, affect descending pathways that module pain perception, reduce ascending pain signal transmission in spinal cord

Question 32

Side effects of opioids

Answer 32

Nausea, vomiting, constipation, dizziness/vertigo, somnolence, dry skin, pruritus, resp depression

Question 33

Best early warning sign of respiratory depression

Answer 33

Progressive sedation

Question 34

Renal failure and opioids

Answer 34

Don't use morphine/codeine - sedative metabolites accumulate, Fentanyl or Oxycodone are okay

Question 35

Epidural analgesia

Answer 35

Directly into epidural space, catheter placed

Question 36

Uses of epidural analgesia

Answer 36

- Postoperatively (thoracic, abdominal, groin/perineal, lower limb surgery) - Labour pain - Chronic pain

Question 37

Benefits of epidural analgesia

Answer 37

- High quality pain relief - Improved pulmonary function - Reduced sepsis and chest infection - Reduced cardiac morbidity - Reduced vascular graft failure - Reduced incidence of DVT

Question 38

Epidural space

Answer 38

Potential space between dura and vertebral canal wall - connective tissue, fat and blood vessels and nerve roots and tissue in folds

Question 39

Morphine

Answer 39

Regular immediate release (4 hourly), allow access for breakthrough pain

Question 40

Celiac plexus block used for

Answer 40

Pancreatic carcinoma and upper abdominal neoplasia

Question 41

Spinal opiods

Answer 41

Act at dorsal horn, lipophobic morphine reaches brainstem, lipophilic fentanyl remains segmentally localised (subarachnoid space)

Question 42

Neuropathic pain

Answer 42

Spontaneous pain and hypersensitivity to pain in associated with damage to/lesion of NS

Question 43

Causes of neuropathic pain

Answer 43

- Post herpetic neuralgia - Painful diabetic neuropathy - Trigeminal neuralgia - Pain after CVA - Post traumatic/post operative

Question 44

Dysaesthesias

Answer 44

Unpleasant abnormal sensations 'ants crawling on the skin'

Question 45

Neuropathic pain prevalence

Answer 45

2-4% population

Question 46

McGill Pain Questionnaire (MPQ)

Answer 46

78 ranked descriptors, time consuming but well validated

Question 47

Drug therapy for neuropathic pain

Answer 47

- NSAIDs (poor) - Antidepressants - Anticonvulsants - Opioids - Membrane stabilising drugs - Topical drugs

Question 48

Antidepressants efficacy (tri-cyclic agents)

Answer 48

Neuropathic pain, complex regional pain syndrome, tension headache (serotonin uptake inhibitors ineffective)

Question 49

Antidepressants mode of action

Answer 49

Inhibit neuronal reuptake of noradrenaline and serotonin (5-HT)

Question 50

Side effects of antidepressants

Answer 50

Constipation, dry mouth, somnolence, abnormalities in heart rate/rhythm, insomnia, increased appetite

Question 51

Anticonvulsants efficacy

Answer 51

Neuropathic pain

Question 52

Anticonvulsants mode of action

Answer 52

- Gabapentin (binds to presynaptic voltage-dependent Ca channels) - Pregabalin (interacts with special N-type Ca channels) - Carbamazepine (blocks Na and Ca channels)

Question 53

Anticonvulsant side effects

Answer 53

Sedation, dizziness, ataxia, peripheral oedema, nausea, weight gain

Question 54

Carbamazepine, phenytoin

Answer 54

Na+ channel blockers > dizziness, sedation, rashes, liver damage

Question 55

Valproate, clonazepam

Answer 55

GABA agonist

Question 56

Loeser conceptualised pain

Answer 56

Four dimensions - pain behaviours, suffering, pain, nociception