painpresentation-100316212754-phpapp02

8/9/2019 painpresentation-100316212754-phpapp02

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ALL ABOUT PAIN


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The nervous system’s response to noxious (harmful)stimuli, also known as “nociception”

Examples of external stimuli: pricking, cutting,crushing, urning, free!ing

Examples of internal stimuli: swelling,

in"ammation, #istention ($ote: These are noxiousstimuli, ut other stimuli must cause these stimuli%swelling, for instance, #oes not usually happen on itsown)

&everal factors contriute to reception of pain

'echanical stimulation from sharp oect

otassium release# from the insi#es of the#amage# cells

rostaglan#ins, histamines, an# ra#ykinin from

&o, +hat is ain, nyway-


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There are Two “+aves” of ain

$ociceptors

.ree nerve en#ings (#en#rites) in the skin thatpick up the information from the painful stimuli

/nly respon#s to extreme pressure ortemperature

.oun# almost everywhere: from skin to teethpulp to oint memranes to muscles

$ociceptors are the #en#rites of nerve *ers

There are two types of axons of these nerve*ers

0#elta *ers

10nerve *ers (two types)


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03E4T $E56E .72E5&

.irst wave of pain (initial pain%sharp an#highly locali!e#)

Thick(er) an# myelinate# (mo#erately fasttransmission)

4imite# to responses from very strongpressure an# extreme temperatures (ten# to

e from imme#iate stimuli)

10$E56E .72E5&

lso known as “olymo#al nociceptors”

&econ# wave of pain (longer0lasting, #uller,wi#esprea# pain)

6ery thin an# unmyelinate# (very slow transmission)

$ot limite# to imme#iate stimuli%also


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9ust a little touchpainhumor;<

;


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$otice that the nociceptors laele# here are locate# in

the E73E5'7& an# that they are .5EE $E56EE$37$=&, or a8erent nerve #en#ritesthat are not encapsulate# (astouch, heat, an# pressurenerve en#ings are)

1utaneous (“7n the &kin”) 5eceptors


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ain’s scen#ing athway to the 2rain

0#elta *ers an# 10nerve *ers form synapseswith #orsal horn of spinal cor#

1ell o#ies in #orsal root ganglia

&ynapse etween primary pain0sensing neurons

an# secon#ary pain0transmission neurons occursin #orsal horn of spinal cor#

&econ#ary neurons sen# signals upwar# throughspinothalamic tract

1ontralateral si#e of spinal cor#

.ace sen#s info through “mini0spinal cor#” calle#trigeminal nerve into the me#ulla


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ropose# y 5onal# 'el!ack an# atrick

+all=rew out of oservations of ++77 veterans

an# their inuries1oncept: pain messages are intercepte# y

speciali!e# nerve cells in the spinal cor#efore they reach rain.or severe pain that coul# lea# to #amage$erve “gate” is wi#e open'essage travels almost instantaneously

.or mil#, weak pain

$erve gate sometimes close#.ilter, lock pain messages

Gate Control Theory


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$erve *ers that transmit touchin"uences gatekeeper cellsTouch stimulate gatekeeper cells to close

“gate”3ecrease pain transmission

5uing sore area > relief

Gate Control Theory Cont’d


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ain an# normal somatosensory neuronsoth synapse on proection cells (whichgo up into rain) an# inhiitoryinterneurons in spinal cor#

$ormal somatosensory signals turns onoth proection an# inhiitory neurons>cancel each other out

/nly pain turns on proection an#inactivates the inhiitory0 lea#ing to pain

Gate Control Theory: In-Depth


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Transmission:

03amage# Tissue0Thalamus0arietal loe an#4imic &ystem01ereral 1ortex

ain an# the 2rain


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+hen humans’ rains are mappe# forresponse to lasers, this area activates<

+hile controversial, one area, the6mpo, causes pain or temperature0

relate# sensations when stimulate#


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'e#ial .rontal 1ortex

This is part of an area involve# incontrolling motivational ehavior

7t activates in response to perceiving

the unpleasantness of pain


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The 3escen#ing athway

3escen#ing system suppresses the

transmission of pain signals from the#orsal horn of spinal cor# to higherrain centers

/riginate in the somatosensorycortex an# hypothalamus

Thalamic neurons suppress

ascen#ing nerve signals at synapsesin mi#rain

eria?ue#uctal =ray


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The $eurotransmitters of 7$ $erves transmitting pain signals, as well asthose involve# in pain regulation, use excitatory

an# inhiitory neurotransmitters

Excitatory $eurotransmitters of ain &ignaling =lutamate%

0$'3 , ', an# metaotropic receptorsare involve# in excitatory synaptictransmission of pain<

0+ith $'3 (10*ers), 'g@@ clogsreceptor

0$eary pepti#e receptorsstimulate# channel opens

03epolari!es the neuron

Tachykinins%


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&ustance (The “ is for ain” 'olecule), aTachykinin

0.oun# in 10*ers0.irst #escrie# y von Euler D =a##um in FC

#uring research of e?uine rain an# intestines0&e?uence# in FG02in#s to $A0 receptors , ut is synthesi!e# y

nociceptors

06aso#ilation (swelling of capillaries) an#release of histamine y mast cells (see elow)

$eurotensin03etecte# #uring isolation of &ustance from

ovine samples01auses vaso#ilation in alrea#y0open woun#s

Histamine

07n mast cells of the immune systemI sutance an# foreign sustances like ee venom cause

T


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T05elease# y #amage# cells an# in#s to T0

gate# channels on nociceptors (then the cell is#epolari!e#


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7nhiitory $eurotransmitters of ain &ignaling 'ost important: =2

04igan#0gate# an# =0protein couple#receptors0'ost important for interneurons (gate0control theory)

=lycine

$eurotransmitters 'e#iating ain 5egulation0&erotonin an# $orepinephrine are involve# intransmission etween neurons of the#escen#ing pathway

0/ften working in tan#em with &ustance


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5emarkale 3iscovery with.os&hows up in the spinal cor# after even riefnoxious stimulation, particularly of 10nerve *ers,ut #isappears after B0G #aysI expression of 10.osgene in #amage# nerves that #o not typicallyexpress .os

n 7n#ucile Transcription .actor, which changesthe internal environment of the cell on a long0termasis

Therefore, provi#es a link etween persistentstimulation an# conse?uences for the future y

gene expressionL

lthough the transcription of10.os is un#erstoo# generally, its


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How the ain +e .eel is 3i8erent

3i8erent types of nerves an# neurotransmitters

$ociceptors are simultaneously activate# withother cutaneous receptors, like mechanoreceptors,giving us:

0ressure0pain0Hot0pain

01ol#0pain0Etc<

s for spicy foo#s;<


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&picy .oo#s are 'o#erate# y 1apsaicin

.irst isolate# as a vanilloi# in re# peppers (thenchilies, alapeMos;


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ain that lasts O months or longerersists long after trauma has heale# or

in the asence of trauma1ommon causes of chronic painhysical prolems stemming from chronic

illness or internal inuriesrthritis: in"ammation of the oints

3amage to peripheral or spinal nerves$europathic pain1an result from acci#ents, infections, surgeryNnknown cause (possily psychological-)

1hronic ain


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utoimmune3iseases'&, lupus

1ancer

1ompressionTrauma1rush nerves

3iaetes

'ost common3rug si#e e8ects

$utritional3e*ciencies

7nfectious 3isease4yme #isease,

herpes, H76Toxic &ustances'ercury, lea#,

arsenic

'ore 1auses of ain an# $erve

3amage


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“/8” erception of ain

llo#ynia%“painful” response to a typicallynon0painful stimulus Hyperalgesia%increase# “painful”

response to a painful stimulus

ain Enhancement #uring illness &tops person from wasting energy 7mmune system interaction-

ain Enhancement after 7nury 3amage torecent activation of

nocioceptors respon# to weaker stimuli

(use of local anesthetics)

&tops person from touchingwoun#s ettin infections

Sensitization


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$ervous system ampli*es an# #istorts pain5esulting pain out of proportion to original inury

or #isease

1auses 7n"ammation: nociceptors *re w greater intensity,

longer time, lower threshol#normal chemical reactions in spinal cor# that

increase transmission of pain messages4ower threshol# of pain receptors Examples of &ensiti!ers: ra#ykinin,

prostaglan#ins, an# sustance

4inke# to sensing, feeling, an# thinking

regions of rain4ea#ing to emotional, psychological su8ering


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2ut 3on’t .orget the 'ost 1urious &ustancll


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7$ 1/$T5/+hich 4ea#s Ns To;;


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3rug0'e#iate# 'anagement


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3rug0'e#iate# 'anagement artial an# full opioi# agonists ex< 'orphine, heroine, fentanyl,oxyco#one, #emerol

$erve terminals of primary pain neuronsin #orsal horn contain opioi# receptors,activation of which inhiits transmitterrelease

7nection of opioi#s into mi#rain cancause profoun# pain relief (connecte# toprimary pain neurons)

11A ntagonists 'u receptor activation releases 11A,which goes on to inhiit opioi# e8ects(through activation of other sustances,such as sustance )

0

$&73


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$&73s 7nhiit prostaglan#in Ten# to inhiit all prostaglan#in%analgesia an#anti0in"ammation, ut no muscle regeneration

nti0Histamines 5e#uce swelling an# irritation at inury site

nti#epressants

&tress07n#uce# nalgesia

En#orphins &uppress glutamate an# hyperpolari!e neurons 7n response to stress an# physical exertion

2elief07n#uce# nalgesia

“laceo E8ect” /ther Therapies &urgery (an extreme) syche#elics an# ca8eine for hea#ache relief

lternative Therapies: hotcol# compresses,chiro ract , massa e,


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ain Tolerance ain tolerance is generally higher in menthan in women, an# #ecreases with age

7n men pain tolerance increasessigni*cantly in repeat testing

5esearchers expect that gen#er role expectations e8ecthow men perform on the test

woman’s aility to han#le pain may also relate to whereshe is in her hormone cycles

7n animal stu#ies it was foun# that females have feweropioi# receptors than males, which may account for gen#er#i8erences<


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'oreconnections

to regions ofthe rain

associate#with external

functions

'oreconnections

to regions ofthe rain

associate#with internal

functions


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n# $ow, &ome +eir# &tu8;;


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Music and Pain

n hour a #ay keepsthe #octor away


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hantom lim pain%pain without stimulior receptors 5amachan#ran 3estruction of nerves an# pain

mo#ulation 'irror therapies


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&1$F, 17 an# Evolution

&1$F instructs the protein so#iumchannel that allows neurons to pass onmessages

7n a stu#y of chil#ren where this wasfaulty, scientists foun# that they felt nopain

They fre?uently it their lips an# two ofthem ha# itten at least a thir# of theirtongue o8< 7n fact, one girl thought it was

funny to ite her *ngers an# see the loo#


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17 is a nerve #isor#er in which the nervesfor sensing temperature an# pain #on’t form

'utations of the $T5A gene%$=.in#ing to Trk receptor on nociceptive ansympathetic nerves not enco#e#

&ome estimate that 17 a8ectsapproximately one in BR,QQQ,QQQ

7ssues:

1ommon infections 0S amputation

cci#entally iting tongue through orclean o8 when eating

3ying of overheating


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ray A “Mechanis(s o% action o% capsaicin-li'e (olecules on sensory neurons ” /i%e Sci +2+1294"+F-E


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ray, A. Mechanis(s o% action o% capsaicin-li'e (olecules on sensory neurons. /i%e Sci. +2+1294"+F-E.!http"##$$$.ncbi.nl(.nih.go3#pub(ed#+99+ED+).

*ields, Go$ard /. “0ain 0erception5he ana 6uide.” 0he #ana Foundation. ?o3. 2F.!http"##$$$.dana.org#ne$s#brainhealth#detail.asp:;id=+F2). 2 *eb. 2+.

*isher, Brian , 0h.. “?SAct. 8,


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?er3e 0ain and ?er3e a(age" Sy(pto(s and Causes. )rain 8 Ner5ous System !ealth Center9 WeM#. >ct. 8,28. !http"##$$$.$eb(d.co(#brain#ner3e-pain-and-ner3e-da(age-sy(pto(s-and-causes). 9 *eb.2+.

L?euroscience %or Kids - eceptors.L P *aculty eb Ser3er. !http"##%aculty.$ashington.edu#chudler#receptor.ht(l ). +*eb. 2+.

“?eurotrans(ission.” 0he Merc" Manuals Online Medical 4irary.; ?o3. 2.

!http"##$$$.(erc'.co(#((pe#sec+E#ch2F#ch2Fa.ht(l). 9 *eb. 2+.

>li3iera, Carlos . . et al. “Spinal Anesthesia in a 0atient $ith Congenital

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