Week 230 - Pain Flashcards
Week 230 - Pain: What are the short-term side effects of morphine?
- Nausea and Vomiting
- Constipation
- Addiction
Week 230 - Pain: What are the long-term side effects of morphine?
- Hormonal imbalance (leading to reduced testosterone, reduced libido, erectile dysfunction, gynaecomastia, fatigue)
- Opioid-induced hyperalgesia.
- Immune system dysfunction.
Week 230 - Pain: How do opioids reduce testosterone?
- Inhibit GnRH
- Low gonadotrophin secretion.
- Reduced gonadal androgen (Testosterone) secretion.
Week 230 - Pain: What is nociceptive pain?
• Pain caused by signals sent by nociceptive receptors in tissues.
Week 230 - Pain: What is neuropathic pain?
• Pain caused by damage to the nerves themselves.
Week 230 - Pain: What are the five levels of Loeser’s model of pain?
1) Nociceptive
2) Attitudes and Beliefs
3) Suffering
4) Pain escape behaviour
5) Social environment
Week 230 - Pain: What is the chronic pain cycle?
1) Pain
2) Fear of movement
3) Avoidance or over-activity
4) Rest
5) Distress, Frustration, Worry
6) Physically De-conditioned
1) Pain
Week 230 - Pain: Give examples of the two main types of drugs used for analgesia.
• Non-opioid analgesics:
- Paracetamol, Ibuprofen, Naproxen
• Opioid analgesics:
- Codeine, dihydrocodeine, fentanyl, morphine, oxycodone, tramadol.
Week 230 - Pain: Which two drugs, indicated for other uses, are commonly used for the treatment of pain?
Gabapentin and amitrityline.
Week 230 - Pain: What are the three steps of the WHO analgesia ladder?
1) Non-opioid analgesic. +/- adjuvants.
2) Weak opioid and non-opioid. +/- adjuvants.
3) Strong opioid and non-opioid. +/- adjuvants.
Week 230 - Pain: What are the adjuvants that may be added to analgesia treatment for pain?
- Bisphosphonates.
- Steroids.
- Muscle relaxants.
- Antidepressants.
Week 230 - Pain: Which opioids are classed as ‘weak’?
Codeine and dihydrocodeine.
Week 230 - Pain: Which opioids are classed as ‘strong’?
Morphine, fentanyl, oxycodone.
Week 230 - Pain: What is the mechanism of action of paracetamol?
• Reduces central prostaglandin synthesis.
Week 230 - Pain: How do NSAIDS work?
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.
Week 230 - Pain: If a patient has any GI risk factors what should you add when prescribing NSAIDS?
PPI
Week 230 - Pain: What are the beneficial effects of opioids?
Analgesia, Euphoria, Sedation, Cough Suppression, Anti-diarrhoeal activity.
Week 230 - Pain: Tramadol also has non-opioid effects, what are they?
• Inhibits the re-uptake of norepinephrine (noradrenaline) and stimulates serotonin release.
Week 230 - Pain: What cautions should be taken when prescribing tramadol?
• Caution taken in patients with risk of seizures, increased risk of CNS toxicities if given with anti-depressants.
Week 230 - Pain: What are the side-effects of opioids?
Common - Nausea and vomiting, Drowsiness, Unsteadiness, Delirium
Occasional - Sweating, Dry mouth, Hallucinations, Pruritus,
Week 230 - Pain: What is the first-line strong opioid analgesic?
Morphine
Week 230 - Pain: Which drug is used to reduce muscle spasm which may be causing pain?
Baclofen
Week 230 - Pain: What is gabapentin?
GABA analogue, reduces neuronal excitability.
Week 230 - Pain: What are the side-effects of gabapentin?
• Drowsiness, confusion, dizziness.
Week 230 - Pain: What are the side-effects of Amitriptyline?
• Drowsiness, arrhythmias, dry mouth, blurred vision.
Week 230 - Pain: Give examples of some of the local anaesthetics that can be used in the treatment of pain?
- Lidocaine patch
- Emla cream (Lidocaine, prilocaine)
- Nerve blocks.
Week 230 - Pain: What is the impact of Congenital Insensitivity to Pain (CIP)?
- Need to ‘learn’ to avoid dangerous behaviour.
- Musculoskeletal problems.
- Shorter life span.
Week 230 - Pain: What is the TRPV1 receptor?
- Capsaicin receptor.
- Pain receptor that reacts to thermal changes.
- It is activated by temperature above 43º.
Week 230 - Pain: Give examples of chemicals that cause sensitization of nociceptors and in turn produce the sensation of pain.
- Histamine
- Prostaglandins.
- Bradykinin.
- Substance P.
Week 230 - Pain: What are the two types of nociceptors?
- A∂ fibres.
* C-fibres.
Week 230 - Pain: What are the characteristics of A∂ (delta) nociceptors?
- Myelinated.
- ‘Fast’ pain sensation.
- Unimodal.
Week 230 - Pain: What are the characteristics of C nociceptors?
- Unmylinated.
- ‘Slow’ pain sensation.
- Unimodal.
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?
- 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.
Week 230 - Pain: Pain travels through which spinal tract?
The spinothalamic, to the thalamus.
Week 230 - Pain: What are the 1st,2nd and 3rd order neurons in terms of the pain pathway?
1st - Nociceptor from pain stimulus to spinal cord.
2nd - Spinothalamic tract to thalamus.
3rd - Thalamocortical from thalamus to cortex.
Week 230 - Pain: At which level does the pain pathway cross the spinal cord?
They decussate at the same level that they enter.
Week 230 - Pain: Which parts of the cortex are responsible for the ‘unpleasant’ sensation of pain?
• Insula and Cingulate cortex.
Week 230 - Pain: Which part of the brain is responsible for locating the source of the pain?
Primary somatosensory cortex.
Week 230 - Pain: What are the three locations that the descending pathways of pain begin from?
- Periaquaductal grey.
- Nucleus raphe magnus.
- Locus coeruleus.
Week 230 - Pain: What are the receptor types for each of the locations of the descending pain pathway?
- Periaquaductal grey - Opioidergic
- Locus coeruleus - Noradrenergic
- Nucleus raphe magnus - Seretonergic
Week 230 - Pain: How does phantom limb pain arise?
- 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.
Week 230 - Pain: What is the difference between opioids and opiates?
They are often used inter-changeably but in reality, opioids are endogenous ligands for opioid receptors. Whilst opiates are exogenous (e.g. morphine, codeine).
Week 230 - Pain: What type of receptors are opioid receptors? What are the main classes of opioid receptors?
- Metabotropic.
* Mu, Delta, Kappa.
Week 230 - Pain: Which class of opioid receptor is the most addictive?
Mu
Week 230 - Pain: What are the three types of opioids? Which receptor type does each have affinity for?
- Endorphins - Agonist for all three but primarily Mu.
- Enkephalins - Primarily a delta-agonist.
- Dynorphins - Primarily a kappa-agonist.
Week 230 - Pain: How do endogenous opioids modulate the pain pathway?
- 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.
Week 230 - Pain: What are the other effects of opioids?
- Euphoria
- Sedation
- Cough suppression
- Respiratory depression
- Nausea and Vomiting
- Constipation
- Miosis
Week 230 - Pain: What is Allodynia?
A stimulus that causes pain when it shouldn’t.
Week 230 - Pain: What is trigeminal neuralgia? How is it treated?
- 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.
