Week 230 - Pain

Question 1

Week 230 - Pain: What are the short-term side effects of morphine?

Answer 1

• Nausea and Vomiting
• Constipation
• Addiction

Question 2

Week 230 - Pain: What are the long-term side effects of morphine?

Answer 2

• Hormonal imbalance (leading to reduced testosterone, reduced libido, erectile dysfunction, gynaecomastia, fatigue)
• Opioid-induced hyperalgesia.
• Immune system dysfunction.

Question 3

Week 230 - Pain: How do opioids reduce testosterone?

Answer 3

• Inhibit GnRH
• Low gonadotrophin secretion.
• Reduced gonadal androgen (Testosterone) secretion.

Question 4

Week 230 - Pain: What is nociceptive pain?

Answer 4

• Pain caused by signals sent by nociceptive receptors in tissues.

Question 5

Week 230 - Pain: What is neuropathic pain?

Answer 5

• Pain caused by damage to the nerves themselves.

Question 6

Week 230 - Pain: What are the five levels of Loeser’s model of pain?

Answer 6

1) Nociceptive
2) Attitudes and Beliefs
3) Suffering
4) Pain escape behaviour
5) Social environment

Question 7

Week 230 - Pain: What is the chronic pain cycle?

Answer 7

1) Pain
2) Fear of movement
3) Avoidance or over-activity
4) Rest
5) Distress, Frustration, Worry
6) Physically De-conditioned
1) Pain

Question 8

Week 230 - Pain: Give examples of the two main types of drugs used for analgesia.

Answer 8

• Non-opioid analgesics:
- Paracetamol, Ibuprofen, Naproxen

• Opioid analgesics:
- Codeine, dihydrocodeine, fentanyl, morphine, oxycodone, tramadol.

Question 9

Week 230 - Pain: Which two drugs, indicated for other uses, are commonly used for the treatment of pain?

Answer 9

Gabapentin and amitrityline.

Question 10

Week 230 - Pain: What are the three steps of the WHO analgesia ladder?

Answer 10

1) Non-opioid analgesic. +/- adjuvants.
2) Weak opioid and non-opioid. +/- adjuvants.
3) Strong opioid and non-opioid. +/- adjuvants.

Question 11

Week 230 - Pain: What are the adjuvants that may be added to analgesia treatment for pain?

Answer 11

• Bisphosphonates.
• Steroids.
• Muscle relaxants.
• Antidepressants.

Question 12

Week 230 - Pain: Which opioids are classed as ‘weak’?

Answer 12

Codeine and dihydrocodeine.

Question 13

Week 230 - Pain: Which opioids are classed as ‘strong’?

Answer 13

Morphine, fentanyl, oxycodone.

Question 14

Week 230 - Pain: What is the mechanism of action of paracetamol?

Answer 14

• Reduces central prostaglandin synthesis.

Question 15

Week 230 - Pain: How do NSAIDS work?

Answer 15

They are competitive inhibitors of COX.

• COX2 - Reduces prostaglandin secretion and therefore inflammation.
• COX1 - GI damage, Renal damage leading to sodium and water retention, Worsens asthma.

Question 16

Week 230 - Pain: If a patient has any GI risk factors what should you add when prescribing NSAIDS?

Answer 16

PPI

Question 17

Week 230 - Pain: What are the beneficial effects of opioids?

Answer 17

Analgesia, Euphoria, Sedation, Cough Suppression, Anti-diarrhoeal activity.

Question 18

Week 230 - Pain: Tramadol also has non-opioid effects, what are they?

Answer 18

• Inhibits the re-uptake of norepinephrine (noradrenaline) and stimulates serotonin release.

Question 19

Week 230 - Pain: What cautions should be taken when prescribing tramadol?

Answer 19

• Caution taken in patients with risk of seizures, increased risk of CNS toxicities if given with anti-depressants.

Question 20

Week 230 - Pain: What are the side-effects of opioids?

Answer 20

Common - Nausea and vomiting, Drowsiness, Unsteadiness, Delirium
Occasional - Sweating, Dry mouth, Hallucinations, Pruritus,

Question 21

Week 230 - Pain: What is the first-line strong opioid analgesic?

Answer 21

Morphine

Question 22

Week 230 - Pain: Which drug is used to reduce muscle spasm which may be causing pain?

Answer 22

Baclofen

Question 23

Week 230 - Pain: What is gabapentin?

Answer 23

GABA analogue, reduces neuronal excitability.

Question 24

Week 230 - Pain: What are the side-effects of gabapentin?

Answer 24

• Drowsiness, confusion, dizziness.

Question 25

Week 230 - Pain: What are the side-effects of Amitriptyline?

Answer 25

• Drowsiness, arrhythmias, dry mouth, blurred vision.

Question 26

Week 230 - Pain: Give examples of some of the local anaesthetics that can be used in the treatment of pain?

Answer 26

* Lidocaine patch * Emla cream (Lidocaine, prilocaine) * Nerve blocks.

Question 27

Week 230 - Pain: What is the impact of Congenital Insensitivity to Pain (CIP)?

Answer 27

* Need to 'learn' to avoid dangerous behaviour. * Musculoskeletal problems. * Shorter life span.

Question 28

Week 230 - Pain: What is the TRPV1 receptor?

Answer 28

* Capsaicin receptor. * Pain receptor that reacts to thermal changes. * It is activated by temperature above 43º.

Question 29

Week 230 - Pain: Give examples of chemicals that cause sensitization of nociceptors and in turn produce the sensation of pain.

Answer 29

* Histamine * Prostaglandins. * Bradykinin. * Substance P.

Question 30

Week 230 - Pain: What are the two types of nociceptors?

Answer 30

* A∂ fibres. | * C-fibres.

Question 31

Week 230 - Pain: What are the characteristics of A∂ (delta) nociceptors?

Answer 31

* Myelinated. * 'Fast' pain sensation. * Unimodal.

Question 32

Week 230 - Pain: What are the characteristics of C nociceptors?

Answer 32

* Unmylinated. * 'Slow' pain sensation. * Unimodal.

Question 33

Week 230 - Pain: When you, for eg bang your knee, you may rub it to alleviate the pain. What is the physiological basis behind this?

Answer 33

* The A-beta fibres are responsible for pressure sensation. * These fibres travel along the same pathway into the spinal cord as A∂ and C fibres. * A-beta stimulation can therefore inhibit the action of the A∂ and C fibres, through inhibitory interneurons, reducing the sensation of pain.

Question 34

Week 230 - Pain: Pain travels through which spinal tract?

Answer 34

The spinothalamic, to the thalamus.

Question 35

Week 230 - Pain: What are the 1st,2nd and 3rd order neurons in terms of the pain pathway?

Answer 35

1st - Nociceptor from pain stimulus to spinal cord. 2nd - Spinothalamic tract to thalamus. 3rd - Thalamocortical from thalamus to cortex.

Question 36

Week 230 - Pain: At which level does the pain pathway cross the spinal cord?

Answer 36

They decussate at the same level that they enter.

Question 37

Week 230 - Pain: Which parts of the cortex are responsible for the 'unpleasant' sensation of pain?

Answer 37

• Insula and Cingulate cortex.

Question 38

Week 230 - Pain: Which part of the brain is responsible for locating the source of the pain?

Answer 38

Primary somatosensory cortex.

Question 39

Week 230 - Pain: What are the three locations that the descending pathways of pain begin from?

Answer 39

* Periaquaductal grey. * Nucleus raphe magnus. * Locus coeruleus.

Question 40

Week 230 - Pain: What are the receptor types for each of the locations of the descending pain pathway?

Answer 40

* Periaquaductal grey - Opioidergic * Locus coeruleus - Noradrenergic * Nucleus raphe magnus - Seretonergic

Question 41

Week 230 - Pain: How does phantom limb pain arise?

Answer 41

* Massive loss of sensory input. * Prolonged Nociceptive stimulation. * There is a re-organisation in the dorsal horn, A-beta fibres may attach themselves to the remaining 2nd-order neurons causing stimulation of the pain pathway and a perception of pain in a limb that is no longer there.

Question 42

Week 230 - Pain: What is the difference between opioids and opiates?

Answer 42

They are often used inter-changeably but in reality, opioids are endogenous ligands for opioid receptors. Whilst opiates are exogenous (e.g. morphine, codeine).

Question 43

Week 230 - Pain: What type of receptors are opioid receptors? What are the main classes of opioid receptors?

Answer 43

* Metabotropic. | * Mu, Delta, Kappa.

Question 44

Week 230 - Pain: Which class of opioid receptor is the most addictive?

Answer 44

Mu

Question 45

Week 230 - Pain: What are the three types of opioids? Which receptor type does each have affinity for?

Answer 45

* Endorphins - Agonist for all three but primarily Mu. * Enkephalins - Primarily a delta-agonist. * Dynorphins - Primarily a kappa-agonist.

Question 46

Week 230 - Pain: How do endogenous opioids modulate the pain pathway?

Answer 46

* Spinal interneurones release enkephalins into the synapse between the 1st and 2nd order pain neurons. * These shutdown synaptic activity by inhibiting neurotransmitter release and hyper-polarizing the postsynaptic membrane. * The interneurons themselves are controlled by opioids.

Question 47

Week 230 - Pain: What are the other effects of opioids?

Answer 47

* Euphoria * Sedation * Cough suppression * Respiratory depression * Nausea and Vomiting * Constipation * Miosis

Question 48

Week 230 - Pain: What is Allodynia?

Answer 48

A stimulus that causes pain when it shouldn't.

Question 49

Week 230 - Pain: What is trigeminal neuralgia? How is it treated?

Answer 49

* An intense episodic pain that is caused by compression of the trigeminal nerve. * It is often triggered by stimulation of the sensory areas of the trigeminal nerve. * It is treated with anti-convulsants e.g. Carbamazapine.