MNP - Pain

Question 1

The pharmacologic properties of Gabapentin in the treatment of neuropathic pain are thought to be due to:

Answer 1

influences the central sensitization by preventing release of the excitatory neurotransmitter glutamate in the dorsal horn via interaction with the a2delta subunit of voltage gated Ca2+ channels

sodium channel blockade

Question 2

def allodynia

Answer 2

pain provoqued by stimulus that does not normally cause pain

Question 3

hyperesthesia

Answer 3

increased sensitivity to stimulation

Question 4

paresthesia

Answer 4

abnormal sensation that can be spontaneous or provoqued

Question 5

hyperpethia

Answer 5

abnormally painfull reaction to a stimulus

Question 6

analgesia

Answer 6

absence of pain in response to apainfull stimulus

Question 7

neuropathic pain mechanisms

Answer 7

1. ectopic afferent activity fom damaged nerve fiber
2. peripheral sensitization (reduced threshold, increase number of heterotropic Na channel due to released chemical mediator, initiation arachnoic acid cascade)
3. central sensitization (release excitatory mol (PLA2 enz, substance P, BDNF) in dorsal horn, second order neuon increased exp Na voltage gaited channel, alt AMPA/NMDA recep)
4. pathologic activation microglia (released inflam mediator such as ATP CCL2=> activ astro and production TNF, IL1B IL6
5. descending facilitatory system via rostral ventromedial medulla
6. phenotypic chnage of Abeta fibers to produce SP

Question 8

amitryptyline

Answer 8

inhib reuptake serot, norepinephrine
antag voltage gaited Na channel
antag NMDA recept

Question 9

amantadine

Answer 9

NMDA antag
enhance effect AINS, gaba, opioid, decrease opioid tolerence

Question 10

Cannabinoids

Answer 10

CB1 in brain, SC , adipose tissue, visceral organs
CB2: hematopoietic and immune cells

CB1: release ach, dopamine, glutamate
modulate opioid, NMDA, gaba recept

Question 11

recept responsive for opioid induced hyperalgesia

Answer 11

NMDA and u

Question 12

fibers types for cut sensation

Answer 12

1. Abeta: low-intensity stimulus (touch, vibration), transmitted to laminae III/IV
2. Adelta: transient noxious stimuli, thermal or mechanical, rapid conduction. Laminae I and II
3. C: increased intensity, thermal, mechanical, chemical. larger receptive field than Adelta. Laminae I and II

Question 13

descending inhibitory system

Answer 13

1. periaqueductal grey matter
2. locus ceruleus (noradrenergic eff from PAG)
3. in cat Kolliker fuse (descending noradrenergic fibers)

substences in dorsal horn which modulate nocicept transmission: GABA, glycine, serot, norepi, endogenous opioids (enkephalin, endorphin, dysnorphin)
block released substance P + post synaptic actions

Question 14

whichj opioid is recomanded for managment of neuropathic pain

Answer 14

methadone: NMDA recept antag and serot reuptake inhib

Question 15

opioids actions

Answer 15

periph: prevent neurotrans release and nociceptor sensitization
centr: modulate aff to substancia gelat (specific effect C fibers not A, not beneficial in allodynia)

Question 16

mechanism ketamin, lidocain

Answer 16

ketamin: binds non competitively to NMDA recept and s-opioid recept, prevention wind-up

lidocaine: sodium channel blocker, block ectopic afferent at the NMDA recept