SDL: Pain

Question 1

what is the difference between nociception and pain?

Answer 1

nociception refers to signals arriving in the CNS resulting from activation of specialized sensory receptors called nociceptors

pain is an unpleasant perception or emotional construct that accompanies nociception “pain is in the brain”

Question 2

major reason why patients seek medical attention

Answer 2

chronic pain

Question 3

the mutation causing congenital insensitivity to pain is where?

Answer 3

the voltage-gated sodium channels

Question 4

medical term for pins and needles

Answer 4

paresthesias, dysesthesias

Question 5

pain caused by a stimulus that is normally not painfu

Answer 5

allodynia

Question 6

triad response to nociception from skin

Answer 6

redness at lesion (due to capillary dilation*)

flare (spread of redness around lesion due to axon reflex*)

wheal (raised region due to exudation* of fluid from capillaries and venules)

Question 7

what is released at fiber terminal after activation of nociceptor?

Answer 7

calcitonin gene-related peptide (CGRP) and SP (substance P)

Question 8

what does histamine release produce?

Answer 8

plasma extravasation and edema = the wheal

Question 9

the primary hyperalgesia is the result of these chemicals being released by nerves or mast cells at the site of injury

Answer 9

bradykinin
histamine
prostaglandins
leukotrienes
CGRP
acetylcholine
serotonin
substance P
nerve growth factor (NGF)

Question 10

where does secondary hyperalgesia occur?

Answer 10

in the CNS at level of spinal cord and thalamus as a result of increased nociceptor activity

Question 11

examples of how action potentials elicit larger synaptic potentials in secondary hyperalgesia

Answer 11

increased numbers of chemical receptors at synapses to make synaptic potentials larger and/or altered receptor dynamics such that their ion channels remain open longer

Question 12

how does allodynia work?

Answer 12

mechanoceptor activation may now elicit pain by activating sensitized pain pathway tract cells

Question 13

what does peripheral neuropathic pain result from?

Answer 13

upregulation of receptors, upregulation of sodium channels

Question 14

disease states/causes for peripherally originating pain syndromes

Answer 14

complex regional pain syndrome, trigeminal neuralgia (tic douloureux), post herpetic neuralgia, diabetic neuropathy, reflex sympathetic dystrophy

Question 15

disorders associated with central pain

Answer 15

spinal cord injury, multiple sclerosis, cerebrovascular accidents (strokes), syringomelia, phantom limb pain, complex regional pain syndrome

Question 16

fiber types that convey nociceptive information

Answer 16

type C (secondary aching pain)

type Adelta (primary, localizing pain)

Question 17

what family of receptors includes nociceptors?

Answer 17

transient receptor potential family

Question 18

what is the gate theory of pain control?

Answer 18

active small afferents keeps pain gate OPEN by inhibiting interneurons that inhibit pain tract cells; active large afferents CLOSE the gate by exciting interneurons that inhibit pain tract cells

Question 19

practical applications of gate control

Answer 19

shaking or rubbing thumb after hitting it with hammer decreases effectiveness of pain fibers to excite pain pathway by closing the gate

rubbing skin before injection

Question 20

inhibitory neurotransmitters released from DORSAL horn of spinal cord

Answer 20

GABA, glycine, opioids (endorphin, encephalin, dynorphin)

Question 21

inhibitory neurotransmitters released by pathway descending from brain

Answer 21

periaqueductal grey to spinal cord dorsal horn: serotonin, norepinephrine, opioids

Question 22

what alteration in the synapses is most important in long standing pain?

Answer 22

at the thalamocortical neurons in the intralaminar nuclei of the thalamus

Question 23

what institutes chronic pain?

Answer 23

if thalamocorticalooping (reciprocal activation) of pain info continues after original source of pain is removed

Question 24

how can chronic pain due to continued thalamocortical looping be relieved?

Answer 24

lesion in the contralateral thalamic nucleus (ultrasound energy targeting, spontaneous mini strokes)

Question 25

regions of the brain responding to nociception (producing pain)

Answer 25

anterior cingulate cortex, prefrontal cortex, insula (cortex), primary motor cortex, primary somatosensory cortex

Question 26

plasma extravasation and edema are due to

Answer 26

substance P

Question 27

primary hyperalgesia is due to sensitization of

Answer 27

nociceptive receptors

Question 28

secondary hyperalgesia is due to

Answer 28

upregulation of receptors in the CNS

Question 29

allodynia is due to sensitization of

Answer 29

spinal cord neurons, thalamic cells

Question 30

pain caused by cancer is this type

Answer 30

mixed neuropathic and nociceptive

Question 31

nociceptive signals activate the ARAS through synapses in which thalamic nucleus or nuclei?

Answer 31

intralaminar nuclei