Lecture 25 - An Introduction to Pain Flashcards Preview

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Flashcards in Lecture 25 - An Introduction to Pain Deck (30):
1

A major concern is when acute pain becomes...

chronic pain - very difficult to treat

2

What are the different types of pain?

Nocioceptive - pin prick

inflammatory - hammer hit

Neuropathic - pain signal trapped in the nervous system = chronic pain

3

Describe Acute nociceptive pain?

Immediate, short duration, localised

NS is activated

relay, amplification, attenuation

Reflex withdrawal response

4

How is the transient potential receptor subunit (TPRV1) - ion channel pore related to pain?

responds to increases in acidity as well as capsaicin (the hot part of chili) and temperature

These are general nociceptors

5

What is the general tissue response to Acute injury?

cell lysis, acid H+, ATP releae


releae of mediators: seretonin histamine, PROSTAGLANDINS, cytokes

nociceptors activated and sensitised

localised pain hypersensitivity occures

6

What are the early and long term changes to nocioceptors?

early inflammation - amplification via receptor threshold and latency reduction

Long term changes - transcription mediated by cytokines and grwoth factors increase production of receptors, ion channels and neurotransmitters, causes Hyperalgesia (think about sunburn sensitivity)

7

What is allodynia?

"pathological response" e.g excruciating pain with light tough - NS has been over-activated and changed to chronic pain stage

8

What nerve fibres are involved in pain?

A-delta and C fibres - 70-90% of peripheral nerve

a-delta: Fast, sharp, acte, pricking localised pain mechanical and thermal pain

c fibres - slow pain aching, throbbing, burning pain, chemical pain

9

Looking at the doral root horn, what is the main excitatory neurtransmitter and which receptors are responsible for pain

Glutamate is main excitatory NT

GABA - is inhibitory NT

NMDA - when Mg2+ is displaced there is cellular remodelling (protracted nociception)

10

Which drug targets NMDA receptors?

Ketamine

11

What other senses inhibit pain?

Endorphins

12

Opioid receptors have a high concentration in the ...

spinal cord

13

What can dampen pain signals going up the spinal cord?

Descending noradrenergic and 5-HT3 fibres

these can inhibit the spinal dorsal horn and dampen incoming signals

14

Amitryptilline simulates what?

The Descending noradrenergic and 5-HT3 fibres

15

Gabapentin act on a ____ channel in the spinal cord

calcium

16

Pain pathways project to ______ _____ and ___-_______ ___ ____

Superior colliculus and peri-acqueductal grey matter (PAG)

stimulation of PAG causes profound anagesia

endogenous opioids activate this area

This forms the basis for deep brain stimulation of intractible pain

17

What happens when a patient has chronic pain?

There is an excessive pain response, leading to abnormal hyper-excitability and structural remodelling = phenotypic change

pain signal EMBEDDED within NS

15-20% can develop chronic neurpathic pan after traumatic injury

18

pain genes can determine pain response

What is the 'Stargazer gene' (CACNG2)

a mutation in stargazin protein

mouse had absense seizures and ataxia in addition to susceptibility to neuropathic pain

19

The human CACNG2 is associated with...

chronic pain! same gene as the one in mouse - research underway...

20

How can genetics lead to lack of sensitivity to pain?

mutation in Na, 1,7 receptor gene - one of the key trasnmitters of pain

21

What enzyme allows the conversion of codeine to morphine?

liver enyme CYP2D6

22

What are the types of analgesic medication?

Opioids (mainstay for severe and moderate pain) - morphine

paracetamol

Aspiriin

NSAIDS

others

23

What are opioid side effects?

Ventilatory depression

drowsiness and sedation

nausea and vomiting

24

What are some pain management stragegies?

Multimodal analgesis - use of smaller doses of opioids in combination with other analgesis drugs

Pre-emptive analgesia - prior to surgery (thery: attenduate injury and neuroplastic repsonse

target nerve transmission - local anaesthesia (Lignocaine)

Remove cognition - general anaesthesia

25

Opiods act not only at the spinal cord but..

at the periphery

26

What are the limitations of Analgesic drugs?

individual responses

inadequate pain control

administration routes

dependance, addiction

multiple side effects

27

What is given to a heart attack patient/

aspirin and morphine

28

child with broken will get what from paramedics?

intranasal opioid - fentanyl - rapid analgesia

29

Migrane pateints will get what in addition to Aspirin, ibuprofen?

vasocontrictors - as part of the problem is cerebral vasodilation

30

What is used for Labour pain?

nitroux oxide

opioids can harm the baby so can't give that..