Pain

Question 1

which type of free nerve ending are important in initial sharp pain

Answer 1

A delta fibres

Question 2

which type of free nerve ending are important in prolonged burning pain

Answer 2

C fibres (unmyelinated)

Question 3

which extremes of temperature are interpreted as painful

Answer 3

below 15C and above 43C

Question 4

which type of nociceptive fibre is polymodal

Answer 4

C fibres

Question 5

In which part of the grey matter do A delta fibres terminate

Answer 5

lamina I, V and X, in the DORSAL HORN
they then excite second order neurones which project to the contralateral side via the anterior commissure and the anterolateral column of the spinothalamic tract

Question 6

in which part of the grey matter do C fibres terminate

Answer 6

the SUBSTANTIA GELATINOSA (lamina II and III), axons pass through the anterior commissure to the contralateral side and rostrally up the spino-reticulo-thalamic tract

Question 7

which membrane protein is activated by capsaicin

Answer 7

TRPV1

Question 8

which membrane protein is activated by menthol

Answer 8

TRPM8

Question 9

which part of the grey matter may be an important site of action for morphine like drugs as there is a lot of opioid peptides and receptors

Answer 9

the substantia gelatinosa

Question 10

which fast neurotransmitters are released by nociceptive afferent neurones

Answer 10

glutamate

ATP

Question 11

which glutamate receptor is important in “wind up” pain

Answer 11

NMDA

Question 12

which glutamate receptor is responsible for fast synaptic transmission in the first synapse in the dorsal horn

Answer 12

AMPA

Question 13

which type of sensory fibre inhibits nociceptive transmission

Answer 13

A beta fibres as they activate inhibitory interneurones

Question 14

what is hyperalgesia

Answer 14

sensitisation of peripheral nociceptive nerve terminals and central facilitation of transmission at the level of the dorsal horn and the thalamus

Question 15

how does neurogenic inflammation contribute to hyperalgaesia

Answer 15

primary afferent neurones release substance P and calcitonin gene-related peptide which promote inflammation by effecting blood vessels and inflammatory cells

Question 16

what is allodynia

Answer 16

perception of pain when stimulus is present but is not normally nociceptive

Question 17

what is parasthesia

Answer 17

perception of pain in the absence of any stimulus

Question 18

what is the periaquaductal grey

Answer 18

area of the midbrain and grey area surrounding the central canal in the spinal cord. It is a descending pathway which controls impulse transmission in the dorsal horn.
It is thought to control the nociceptive gate

Question 19

which two neurotransmitters are involved in the periaqueductal grey projection and how do they work

Answer 19

5HT
enkephalins
they act either directly or via interneurons to inhibit the discharge of spinothalamic neurones

Question 20

what effects do opioid have on descending inhibitory pathways of pain

Answer 20

many effects

1) activated descending inhibitory pathways
2) inhibit transmission in the dorsal horn
3) inhibit excitation of peripheral nerves

Question 21

how is GABA involved in modulation of pain

Answer 21

activation of interneurones in the dorsal horn causes GABA release which inhibits the primary afferent terminals

Question 22

how is the noradrenergic pathway involved in the modulation of pain

Answer 22

noradrenergic pathway originated in the LOCUS COERULEUS and has an inhibitory effect on the dorsal horn.
It is thought that TCA work via the potentiation of this pathway

Question 23

In the descending inhibitory pain pathway which receptors do the purinergic pathway act on?

Answer 23

they release adenosine on to the A1 receptors on the dorsal horn neurones

Question 24

how can the sympathetic nervous system play a part in neuropathic pain

Answer 24

damaged sensory neurones can express alpha adrenoceptors and develop sensitivity to noradrenaline - sympathetic responses can produce severe pain

Question 25

what are enkephalins

Answer 25

members of the endorphin family which are a group of endogenous opioid peptides

Question 26

why should opioids be avoided in asthmatic patients

Answer 26

opioids cause mast cells to release histamine which can potentially cause bronchospasm. Other effects of this might be hypotension and urticaria

Question 27

why must morphine doses be lowered in patients with renal failure

Answer 27

Although morphine is inactivated by the liver, morphine-6-glucuronide is excreted in the urine

Question 28

why should morphine/morphine based analgesics be avoided at childbirth

Answer 28

It also should not be give to newborns. neonates have a low conjugating capacity, therefore the liver in unable to metabolise all the morphine into morphine-6-glucuronide. Morphine therefore stays in the circulation and can cause respiratory depression. For this reason pethidine is the safer alternative to use

Question 29

what is diamorphine also known as

Answer 29

heroin | conversion to morphine is rapid in aqueous solution and in the brain hence the "buzz" when administered IV

Question 30

fentanyl, alfentannil, sufentanil and semifentanil are examples of what

Answer 30

highly potent pehylpiperdine derivatives with similar action to morphine. Used mostly in anaesthetics but also used in severe chronic pain Rapid onset of action

Question 31

what is naltrexone

Answer 31

a long acting opioid antagonist used in the treatmetn of addiction as it reduces euphoria upon opioid administration also used in reducing alcohol consumption also effective in treating chronic pruritus

Question 32

why might paracetamol be combined with opioids?

Answer 32

it has an opioid sparing effect

Question 33

why is there an individual variability to morphine

Answer 33

``` altered metabolism or sensitivity of receptors eg mutations of CYP450 P-glycoproteins glucuronyltransferase mu receptors ```

Question 34

what are the non-opioid properties of tramadol

Answer 34

inhibits reuptake of NA and ***stimulates 5HT release***

Question 35

name 2 weak opioids

Answer 35

codeine dihydrocodeine ? tramadol

Question 36

why does methadone have less of a withdrawal effect

Answer 36

it has a long half life

Question 37

why is a short half life advantageous for remifentanyl

Answer 37

good as a sedative

Question 38

why must you be careful coprescribing tramadol and antidepressants

Answer 38

tramadol also stimulates serotonin release

Question 39

list four safety concerns with NSAIDS

Answer 39

GI damage Damage to kidneys (renal perfusion) Sodium and water retention (as a result of renal) Worsening of asthma

Question 40

how might you assess nociceptive or neuropathic pain

Answer 40

Leeds assessment of neuropathic pain

Question 41

how do anti-epileptics aid analgesia

Answer 41

they reduce neuronal excitability | egs gabapentin and carbamazepine

Question 42

why should pregabalin be prescribed instead of gabapentin

Answer 42

it works the same but is cheaper!!

Question 43

how does amitriptyline work as an analgesic

Answer 43

proposed mechanisms: - sodium channels - better sleep - better mood

Question 44

what are the side effects of amitriptyline

Answer 44

- drowsiness - arrhythmias - dry mouth - blurred vision

Question 45

how does ketamine work

Answer 45

it is an NMDA receptor antagonist which probably reduces wind-up phenomenon in the dorsal horn has many psychotropic effects

Question 46

opioids activate the descending pathways that inhibit pain transmission by acting on neurones in the...

Answer 46

periaqueductal grey matter

Question 47

the vanilliod receptor activated by capsaicin is a...

Answer 47

ligand-gated cation channel

Question 48

the analgesic effect of morphin is mostly due to activation of

Answer 48

mu opioid receptors

Question 49

what effect does stimulation of opioid receptors have on adenylyl cyclase activity

Answer 49

it decreases it

Question 50

give an example of a partial mu receptor agonist

Answer 50

buprenorphine

Question 51

name a short acting opioid agonist used as a transdermal skin patch

Answer 51

fentanyl

Question 52

activation of kappa opioid receptors is responsible for causing ...

Answer 52

dysphoria

Question 53

which finding typically occurs in opioid poisoning but not in central nervous system depression due to other causes

Answer 53

pinpoint pupils

Question 54

which transmitter is released at the first synapse in the dorsal horn ascending nociceptive pathway

Answer 54

glutamate

Question 55

what is the typical age of onset for trigeminal neuralgia

Answer 55

6th or 7th decade - usaully due to ectatic vascular loop pressing on the pons or nerve in younger patients may be a sign of MS (esp if bilateral) or tumours (acoustiv schwannomas, meningiomas, epidermoids)

Question 56

how does trigeminal neuralgia present

Answer 56

knife/shock like pain down the distribution of the Vth nerve tends to begin in V3 and then spread to V2 Stimuli to pain include washing, shaving, cold winds or chewing. Spontaneous remission tends to last months/years

Question 57

how do you treat trigeminal neuralgia

Answer 57

carbamazepine or other anti-epileptics Surgical options include percutaneous radiofrequency selective ablation or microvascular decompression of the nerve (90% success rate)

Question 58

what is postherpetic neuralgia

Answer 58

pain lasting for more than 4 months following shingles develops in 10% of pts(esp elderly) poor response to analgesic gradual recovery takes around 2 years

Question 59

what it complex regional pain syndrome type II

Answer 59

causalgia is a chronic burning pain that occasionally follows nerve damage

Question 60

from the three groups of endogenous opioids, which receptors do they act on

Answer 60

endorphins - all three but strongest for mu enkephalins - delta dynorphins - kappa agonist

Question 61

what is the peak end rule of pain

Answer 61

different parts of pain experience carry greater weight (i.e. lower intensity at the end is better than ending on high intensity) ending abruptly during high pain intensity leaves an unfavourable impression

Question 62

what causes post stroke pain

Answer 62

small thalamic infarcts pt will present with hemiparesis and sensory loss as weakness improves pt will have deep seated constant pain in paretic limbs