Musculoskeletal Pain 2011

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Musculoskeletal PainDewi Irawati

Department of PhysiologyMedical Faculty Universitas Indonesia


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ObjectivesDe nition classi cation and characteristicsMolecular and cellular neurophysiology

!ransduction !ransmissionPerceptionModulation integration and synaptic plasticity"ensiti#ation $peripheral%central&

Factors a'ecting(enetic)motion*ognitive+ehavior


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Objectives

"pecial muscle pains , Ischemic*ramp DOM" $Delayed Onset Muscle"oreness&Problem musculoskeletal painespecially -"I $-epetitive "trainInjury&

!he basic of musculoskeletal painmanagement


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.hat is Pain/

01n unpleasant sensory andemotional e2perience3 Merskey and +ogduk 4556Pain is recogni#ed as a comple2phenomenon derived from sensorystimuliPain is interpreted by the individual

!here are no biological markers for pain"elf,reporting is the most accurateevidence of pain


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Pain

1n unpleasant sensory and emotional$psychological& e2perience associated 7ithactual or potential tissue damage or

described in terms of such damage8(Association for the Study of Pain)

Four main dimensions9Sensory-discriminatory

Afective and emotionalCognitiveBehavioral


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Pain

1 comple2 e2perience embracing physical, mental , social, and

behavioral processescompromising the :uality of lifeof many individuals 8 (SSI Commission For Evaluation of Pain)


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Pain

Major symptom in many medicalconditions and can signi cantlyinterfere 7ith a person;s :uality of life and general functioning8

Motivates us to 7ithdra7 from

potentially damaging situations protecta damaged body part 7hile it heals andavoid those situations in the future8

http://en.wikipedia.org/wiki/Quality_of_lifehttp://en.wikipedia.org/wiki/Quality_of_life


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.hy is it Important toFocus on Pain/

A symptom most expected and most feared bydying patients.Unrelieved pain can have enormous

physiological and psychological effectsPain negatively affects the quality of life byimpairing daily functions, social relationships,sleep and/or self worth.

Although pain can be relieved in up to 9 !cases, many patients receive inadequate or notreatment


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Unrelieved Pain

*hronic $moderate to severe& pain

Often reported by patients as0OU! OF *O=!-O>3

0!hey had not found ade:uate relief3despite ne7 advanced pain

medications


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*onse:uences


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Inade:uate pain management

1ttitude of doctors nursesand patient

Fear of drug usage $narcotics&Insu?cient kno7ledge

>a7s and regulation


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"omatic Path7ays

Receptor !hreshold1ction potential

Sensory neuronsPrimary @ medulla"econdary @ thalamus

!ertiary @ corte2Integration

-eceptive eldMultiple level


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!-1="DU*!IO= 1=D !-1="MI""IO=

!ransduction occurs as the energy of the stimulus is convertedto electrical energy8

!ransmission of the stimulus takes place 7hen this energycrosses into a nociceptor at the end of an a'erent nerve ber8

!7o types of peripheral nerve bers conduct painful stimuli9the fast myelinated 1,delta bers and the very small slo7unmyelinated *, bers8A- bers send sharp distinct sensations that locali#e thesource of the pain and detect its intensity8C- bers relay impulses that are poorly locali#ed burning andpersistent8 For e2ample after burning a nger a personinitially feels a sharp locali#ed pain as a result of 1, bertransmission8 .ithin a fe7 seconds the pain becomes moredi'use and 7idespread as a result of *, ber transmission8


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Connections between primary a erent bers and the spinal cord

1P along primarynociceptor a'erent causesthe release of transmitters

$eg glutamate and Psubstance& from the nerveterminal 7hich thenstimulates secondaryneurons in the dorsal hornof the spinal cord 7hich inturn send the no2ioussignal to the brain8 1PBaction potential8 $*ourtesyof )lan *orporation&

http9%%7778springerimages8com%Images%Medicine1ndPublic


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Connections between primary a erentbers and the spinal cord

!here is a veryprecise laminarorgani#ation ofthe dorsal horn ofthe spinal cordHsubsets ofprimary a'erent

bers targetspinal neurons

7ithin discretelaminae8

!heunmyelinatedpeptidergic *$red& andmyelinated 1nociceptors$purple&terminate mostsuper ciallysynapsing upon

http9%%7778ncbi8nlm8nih8gov%pmc%articles%PM*GJKG 6L


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a erent bers and the spinalcord

!he unmyelinatednon,peptidergicnociceptors $blue&target smallinterneurons $blue& inthe inner part oflamina II8

+y contrast innocuousinput carried bymyelinated 1 fibersterminates on PN*$yello7& e2pressinginterneurons in theventral half of the

inner lamina II81 second set ofprojection neurons7ithin lamina $purple& receiveconvergent input from1 and 1 fibers8

http9%%7778ncbi8nlm8nih8gov%pmc%articles%PM*GJKG


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Pathways1 subset of the

projection neuronscrosses over to theopposite side of thespinal cord ascendto the higher centersin the brain via the

spino,thalamic tractsto the thalamus andhigher centers of thebrain including thereticular formationlimbic system and

somato,sensorycorte2 providinginformation about thelocation and intensityof the painfulstimulus8


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1natomy of the pain path7ay

Other projection neurons engagethe cingulate and insularcortices via connections in thebrainstem $parabrachial nucleus&and amygdala contributing tothe a'ective component of thepain e2perience8

!his ascending information alsoaccesses neurons of the rostralventral medulla and midbrainperia:ueductal gray to engagedescending feedback systemsthat regulate the output from thespinal cord8

http9%%7778ncbi8nlm8nih8gov%pmc%articles%PM*GJKG


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P)-*)P!IO=

.hen pain stimuli reach the cerebralcorte2 the brain interprets the signalHprocesses information from e2periences

kno7ledge and cultural associationsH andperceives pain8

!hus perception is the a7areness ofpain8 !he somatosensory corte2 identi esthe location and intensity of pain and theassociated corte2 determines ho7 anindividual interprets its meaning8


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Perceptual categories

Pric ing !"irst pain#Quality9 sharp

!emporal9 Initial pain sensation – Brie P=" a2ons9 Aδ fibersCNS pathway: Somatosensory to thalamus &cortex


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Perceptual categories

$urning !second pain#Quality9 Dull, aching npleasant

!emporal9 !ater, more long-lasting painsensationP=" a2ons9 C "#ers*="9 $ormatio resticularis %eria&ueductal gray 'ypothalamus Central thalamus


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MODU>1!IO=Once the brain perceives the pain the bodyreleases neuromodulators such as endogenousopioids $endorphins and enkephalins& serotoninnorepinephrine and gamma aminobutyric acid8

!hese chemicals hinder the transmission of painand help produce an analgesic pain,relievinge'ect8

!his inhibition of the pain impulse is calledmodulation 8 !he descending paths of the e'erent

bers e2tend from the corte2 do7n to the spinalcord and may inRuence pain impulses at the levelof the spinal cord8


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=eural Pain Path7ay"timulation of thedescendingpath7ays can reduceand even abolishsome forms of pain8Many animals $andhumans& appear totolerate pain andsho7 very fe7behaviouralalterations follo7ing

a painful insult8 !hismay be due in partto the centralinhibitory e'ects andin part to otherbiological factors8

http9%%iris8u7aterloo8ca%ethics%animals%**1*Emodules%modul

!he diagram sho7s path7ays coming from thebrain do7n to the spinal cord8


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Musculoskeletal Pain

Pain induced bymusculos eletal disorder

$skeleton muscles cartilage tendonsligaments joints and otherconnective tissue &

http://en.wikipedia.org/wiki/Skeletonhttp://en.wikipedia.org/wiki/Musclehttp://en.wikipedia.org/wiki/Cartilagehttp://en.wikipedia.org/wiki/Tendonshttp://en.wikipedia.org/wiki/Ligamentshttp://en.wikipedia.org/wiki/Jointshttp://en.wikipedia.org/wiki/Connective_tissuehttp://en.wikipedia.org/wiki/Skeletonhttp://en.wikipedia.org/wiki/Skeletonhttp://en.wikipedia.org/wiki/Connective_tissuehttp://en.wikipedia.org/wiki/Jointshttp://en.wikipedia.org/wiki/Ligamentshttp://en.wikipedia.org/wiki/Tendonshttp://en.wikipedia.org/wiki/Cartilagehttp://en.wikipedia.org/wiki/Musclehttp://en.wikipedia.org/wiki/Skeleton


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Musculoskeletal Pain , +ackground

*ommonest cause of acute andchronic pain1cute9 muscle cramps ankle sprainsetc*hronic9 e8g8 pain from arthritis andlo7 back pain very 7idespreadproblemsImportant protective role8 Protects

joints from overuse8 Soint damagedevelops in pain,insensitive


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.hat are muscle=ociceptors/

"ensory receptors that responds topotentially damaging stimuliFree nerve endings>ocated in the muscle membrane

joints


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Fibre type Muscle/Joint Cutaneous

Small myelinated Group III A delta

Non myelinated Group I! C

Di'erent terminology used for muscle or joint nerves fromthat used for cutaneous nerves

*lassi cation of a'erent nervebers


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!ypes of (roup III and I a'erentunits

=ociceptors8 !he majority8 Mostpolymodal some mechanical some0sleeping%silent3 8 =o obvious di'erence

bet7een (roup III and I $unlike skin&8)rgoreceptors8 Only muscle not joints8-espond to muscle contraction and tonormal metabolites $e8g8 lactate&8

!hermoreceptors8 "mall numbers ofsensitive thermoreceptors have beendescribed from skeletal muscle8


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=O*I*)P!O-"One particular nociceptor vanilloid receptor,4$ -4& relays sensory messages to the brain inresponse to thermal and painful chemical stimuli

generally regarded as the major pain sensor8.hen the cellular environment becomes acidicboth -4 and a second nociceptor , acid sensingion channels $1"I*s& , are activated8PG receptors the ionotropic receptors activatedby 1!P is underscored by the variety of painstates in 7hich this endogenous ligand can bereleased8 PG receptors can be involved in painmechanisms both centrally and in the periphery8


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Somatosensory speci city%


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"ensiti#ation

1n increase in the e2citability ofneurons more sensitive to stimulior sensory inputs

!7o forms9responsi&eness is increased so thatno2ious stimuli produce an e2aggerated

and prolonged painthresholds are lowered so that stimulithat 7ould normally not produce painno7 begin to $allodynia&


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"ensiti#ation of joint and musclenociceptors

InRammation produces markedsensiti#ation in many joint andmuscle nociceptors8"ilent $0sleeping3& nociceptors startto re 7hen inRammation occurs8


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InRammatory Pain


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*entral "ensiti#ation

Increase in the e2citability of neurons7ithin the central ner&ous systemnormal inputs begin to produceabnormal responsesAltered strength of synapticconnections bet7een the nociceptor

and the neurons of the spinal cord$activity,dependent synaptic plasticity&8Involving many transmitters


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"pinal cord neurons responding tono2ious musculoskeletal stimuli

1'erents terminate predominantly in lam Iand $like noci cutaneous a'erentsH unlikenon,noci muscle a'erents&

Only responding to strong no2ious inputs$noci speci c&.ide dynamic range neurons 7ith deepsomatic elds are found*entral sensiti#ation in response to muscleor joint inRammation is readily seenHthresholds fall and receptive elds enlarge


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InRammatory pain from muscle and joint

InRammation is a major cause ofmuscle and joint pain e8g8rheumatoid arthritis=ociceptor sensiti#ation play a largepart"trong evidence for centralsensiti#ation"timulation of muscle nociceptors isvery e'ective in generating spinalcord 07ind,up3


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Special muscle painIschemic muscle pain

*ontraction 7ith reduced bloodsupplyProlonged contractionMajor problem in elderly 7ithperipheral vascular disease$Intermittent claudication(1ngina is ischemic muscle pain fromthe heart"everal metabolic diseases causee2ercise,induced ischemic pain


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Special muscle painDOM"

Delayed onset muscle sorenessJ hours post e2ercise @ several days1ssociated 7ith eccentric contractione8g8 running do7nhill-educed on repetition of e2ercise

Probably triggered by slo7lydeveloping inRammation


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Musculoskeletal pain conditions ofuncertain cause

Fibromyalgia

>o7 back pain

-"I


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Most common chronic pain problem*ause sometimes clear @ e8g8 discprotrusionOften no obvious pathologyOften 7ork,related 1 majoreconomic problem as 7ell as healthissue8

)usculos*eletal pain conditions o uncertain cause

>o7 back pain


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=early as common as lo7 back pain1'ects a relative young age group.ork related/ $Patient usually think so @ blamekeyboard or light industrial 7ork&

Often leads to job loss @ add stress toalready stressful situation

)usculos*eletal pain conditions o uncertain cause

-epetitive "train Injury , -"I


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.hat is evidence for organic disease in -"I/"ensory changes8 )levated vibrationthreshold reduced Rare $(reening S8 >ynn +8 W>eary -8 $GCCL&8 Pain 4C6 $4,G& G K,GJ4&

*hanges in the median nerve environmentsu?cient to impede normal sliding duringlimb movements $(reening S8 et al8 $GCC4& S


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"tress

-epetitivemechanicalstress

1ltered peri,pheral nerveenvironment8Multiple sites

)ctopicring

$X=ervinervorum/&

*entralnociceptive%painsystems

P1I=

Psychosocial factors

Musculo,skeletaltissueinRammation

=ociceptorsensiti#ation

From >ynn GCCK !e2tbook of Pain K th e


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Pain Management


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"on Pharmacology

Pharmacology

Physically Psychology

Acupuncture

#assage

$urgical

Pain%iller&s'rugs

Anesthetic'rug&s

Psychotherapy

Physical(xercise

)ranquili*er


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Most common cause of acute andchronic painPain is a 7arning signal that helps toprotect the body from tissue damageand has an essential function insurvival8

!here are 6 steps in pain mechanism9transduction, transmission, modulation,%sensation and perception 8


"ummary

l k l l


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"ummaryPlentiful of muscle and jointnociceptors readily sensiti#ed

!he role of cerebral corte2 in painperception is to modulatenociceptive impuls8"pecial muscle pains such as cramp$ischemia& and DOM" $inRammation&are reasonably 7ell understood

M l k l l P i


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"ummaryImportant chronic musculoskeletalpain conditions $ bromyalgia >+P-"I& are less 7ell understood8=eurological aspects may be moreimportant

!he treatment of musculoskeletal

pain is based on pain mechanismsand path7ays


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Useful 7eb,sites

http9%%7778georgiapainphysicians8com%lG EeduEpharmaEmodGEslides8htmhttp9%%7778arch7ay8ac8uk%1ctivities%Depar

tments%"


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'han (ou

Musculoskeletal Pain 2011

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