pain and analgesics 1

Question 1

define pain

Answer 1

pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage
it is a perception that occurs in the brain caused by the activation of nociceptors by thermal, mechanical, chemical or other stimuli

Question 2

what are the types of nociceptive pain? how can they be divided?

Answer 2

cam be divided into visceral pain and somatic pain, referred pain, radiating pain, breakthrough pain, psychogenic pain, phantom pain

Question 3

what is visceral pain?

Answer 3

is diffuse, difficult to locate, and often referred to a distant, superficial structure

Question 4

what is somatic pain?

Answer 4

superficial pain: activation of nocieptors in the skin or other superficial tissue; sharp or burning, well defined
deep somatic pain; activation of nociceptors in ligaments, bones, tendons, fasciae, muscles, dull aching, poorly localized

Question 5

what is referred pain?

Answer 5

perceived at a location other than the site of the painful stimulus

Question 6

what is radiating pain?

Answer 6

pain that spreads from the original area outwards to another part of the body

Question 7

what is breakthrough pain?

Answer 7

is a transitory flare up of pain against a background of otherwise well controlled pain

Question 8

what is psychogenic pain?

Answer 8

result of some underlying psychological disorder

Question 9

what is phantom pain?

Answer 9

refers to a patient’s experience of pain in a part of the body that has been removed surgically or traumatically

Question 10

what is neuropathic pain?

Answer 10

pain that follows direct injury to a peripheral nerve

Question 11

how is neuropathic pain characterised?

Answer 11

partial or complete damage to or dysfunction of the somatosenory pathways in the PNS AOR CNS and
the occurance of pain and hypersensitivity phenomena within the denerated zone and its surroundings

Question 12

who is neuropathic pain observed in?

Answer 12

diabetics and in carpal tunnel syndrome or sciatica
following traumatic injury, inducing ischemia, radiation therapy, excessieve alcohol consumption, immune system disease, coeliac disease or viral infection

Question 13

what are the different types of diabetic neurpathic pain?

Answer 13

peripheral- sensory neuropathy- feet/legs
autonomic- results from damage to nerves which controls involuntary functions
focal neuropathy- results from injury to a peripheral nerve at one site

Question 14

what is neuropathic pain insensitive to?

Answer 14

morphine and other opioid drugs

Question 15

how can neuropathic pain be significantly relieved?

Answer 15

TCA- Amityuptyline
anticonvulsant agents- carbamazepine
corticosteroids- dexamethasone- may produce substantial improvement in some cases in neurpathic pain associated with cancer

Question 16

what is trigeminal neuralgia?

Answer 16

is a neuropathic facial pain condition

• pain/ loss of sensation in the face
• severe paroxysmal, lancinating facial pain
• triggered by innocuous stimuli
• a disorder of the 5th cranial nerve

Question 17

what is the trigeminal nerve?

Answer 17

it is the 5th and largest of the 12 pairs of crianial nerves
the chief nerve of sensation for the face
contains sensory fibres for the face, as well as a motor segment important for mastication- chewing

Question 18

what does the trigeminal nerve divide into?

Answer 18

3 brances:
1- ophthalmic division- V1- provides sensation to the forehead and eye
2-maxillary division-v2- provides sensation to the cheek, upper lip and roof of the mouth
3- mandibular division-V3- provides sensation to the jaw and lower lip

Question 19

what are the treatments for trigeminal neuralgia?

Answer 19

carbamazipine

alt: oxcarbazepine, gabapentin, phenytoin, baclofen, amitryptyline

Question 20

what assessment tools are there for pain?

Answer 20

wide range. these are grouped into categories: uni-dimensional and multi-dimensional methods

Question 21

what are the uni-dimensional assessment tools?

Answer 21

VAS
VRS
NRS
graphic rating scales
verbal descriptor scales
body diagrams
computer graphic scales
picture scales

Question 22

what are some multi-dimentional assessment tools?

Answer 22

McGill pain questionnaire
bried pain invintory
west-haven- yale 
treatment outcomes pain inventory
behavioural pain scales
pain disability index
pain information and beliefs questionnaire

Question 23

what does pseudo-unipolar mean?

Answer 23

a neuron, which means they have a single axon extending from the cell body that forms two extensions: the dendrites and the axon- most sensory neurons

Question 24

how are sensory receptors classified?

Answer 24

sensory receptors are classified into different categories based on their structure, location and type of stimulus

Question 25

what are some types of sensory receptor classificatins?

Answer 25

chemoreceptor, mechanoreceptor, photoreceptor, thermoreceptor. nociceptor

Question 26

what is a nociceptor?

Answer 26

it is a sensory receptor that detects a wide range of stimulus modulates different chemical or physical stimuli can excite nociceptors by activating a single receptor

Question 27

what do nociceptors release?

Answer 27

they are excitory neurons and release glutamate as their primary neurotransmitter

Question 28

what threshold does a nociceptor have?

Answer 28

elevated stimulated threshold encode the intensity of a stimulus within the noxious range i.e. it must not saturate when a stimulus reaches noxious levels

Question 29

what are the different types of nociceptors?

Answer 29

thermal nociceptors, mechanical nociceptors, chemical, polymodal, silent

Question 30

what is the ascending pathway?

Answer 30

refers to the neural projections by which sensory information travels the periphery to the brain

Question 31

what are the major ascending pathways?

Answer 31

the dorsal column: first order neurons consist generally of AA and Ad fibres spinothalamic tract: the laterla ad and C fibres and the anterior spinothalamic tract Ab fibres the spinocereballar tract

Question 32

how do the neurons act in the pain pathways?

Answer 32

1st order neurons- signals from the periphery to the spinal cord or to the medulla 2nd order neurons- signals from the spinal cord or medulla to the thalamus 3rd order neurons- signals from the thalamus to the primary sensory cortex

Question 33

what do the 1st order neurons do in the ascending pathway?

Answer 33

a sensory stimulus is signalled simultaneously via- fast-conducting Aa or Ab fibres slow conducting C and Ad fibres

Question 34

what do the second order neurons do in the ascending pain pathway?

Answer 34

form the ascending spinothalamic tract, which projects tonuclei in the medualla and midbrain on the way up to the thalamus. from thethalamus, the signal is carried by 3rd order neurons

Question 35

what do the 3rd order neurons do in the ascending pathway?

Answer 35

with their cell bodies in the thalamus, project to the somatosensory cortex and to limbic cortical areas

Question 36

what does PAG project?

Answer 36

PAG projects from the anteriour cingulate. | to the RVM and DLPT which send desceding path modulatory projections back to the afferent pathways

Question 37

what is the role of the descending pain pathway?

Answer 37

modulates pain sensation with by enhancing or inhibiting the conduction of pain

Question 38

what does the descending pain pathway include?

Answer 38

anterior cingulate and insular cortex periaqueductal gray nuclei in the amygdala and pvg of the hypothalamaus DLPT and RV,

Question 39

WHAT neurotransmitters are involved in the descending pain pathway?

Answer 39

``` opididergic noradrenergic serotonergic cholinergic GABA-ergic endocannabinoids ```

Question 40

what does PAG receive/ send projections to?

Answer 40

recieves: anterior cingulate, insular, prefrontal cortex, hypothalamus, amygdala and nucleus accumbens sends: dlpt and rvm

Question 41

what are the neurotransmitters involved in the descending pathway?

Answer 41

opioids, NA, GABA ,ACH, endocannabinoids

Question 42

what is the spinal chords role in descendinh pain pathway?

Answer 42

recieves imput from the RVM - 5ht release hyperpolarisation of ascending fibre and dorsal horn projection with 5HT1 receptors depolarisation of spinal GABAergic internueons with 5HT2A, 5ht3 receptors

Question 43

what happens when the spinal chord recieves imput from DPLT?

Answer 43

- adrenergic cell clusters in the rostral medulla oblongata noraderergic nuclei is the locus coreuleus abd sub-coereus regions hyperpolarisation of projection neurons when interacting with a2A repectors hyperpolarisation of primary afferent fibres with a-2B/C receptors depolarisation of dorsal horn inhibitory interneuons via a-1A receptors

Question 44

how does 5HT release occur in the descending pathway?

Answer 44

hyperpolarization when interact with 5-HT1 R | depolarization when interacts with 5HT2 R or 5HT3 r

Question 45

how is NA released in the descending pathways?

Answer 45

hyperpolarisation of projection neurons when interact with a-2A R, and of sensory nerons when interacts with a-2B/C depolarisation of forsl horn inhibitory of interneuorns via a-1A r