Update in Pain Management

8/2/2019 Update in Pain Management

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Update in Pain Management


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Defining of PainPain Experience

Pain is a personal, subjective experience that

comprises :Sensory-discriminative, Motivational-affective

So

matiz

atio

???

??

Dep

ressio

n

Expe

c

t

at

Anx

iety

Cat

astr

oph

An unpleasantsensory andemotional experience

associated withactual or potentialtissue damage, ordescribed in terms ofsuch damage.

InternationalAssociation for theStudy of Pain (IASP)1994, Kyoto ProtocolIASP 2008


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Classification of Pain

Physiologic / nociceptive:1 Pain arising from activation of nociceptors Caused by mild and short noxious impulses which usually relieved without any

medication or mild analgesics Example: Pinched, stung by mosquito

Inflammatory:2

Pain caused by injury to body tissues (musculoskeletal, cutaneus or visceral) Example: Pain due to inflammation, limb pain after fracture

Neuropathic:1 Pain arising as a direct consequence of a lesion or disease affecting the

somatosensory system Example: DPN, PHN

Psychogenic (functional):3 Pain due to abnormal responsiveness or function of the nervous system

without neurologic deficit or peripheral abnormality. Example: Fibromyalgia, irritable bowel syndrome


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fracture /Postoper

ative

Ongoing orimpending

injury

sprain

Inflamation /

Infection Infiltrated orcompressed

(tumors)

strangulated(scar

tissue)MuscleStretch

inflamed(infection

)

Type or Category of Pain

3.Psychogenic

clear thatno

somaticdisorder

is present

1. Nociceptive-

Inflamatorik

Caused byactivity

in neuralpathways

in responseto

potentiall

2.

Neuropathic

Initiated orcaused by

primarylesion ordysfunctio

nin the

nervouss s.

4. Mixed type

Caused by acombination of

both

primary injuryorsecondary

effects

The Assessment of the Patient with Pain, Steven Richeimer, M.D. Director USC Pain Management, USC Medical Center, Los Angeles,

Myofascial pain


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The Continuum of Pain1


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Dorsal Horn

Dorsal rootganglion

Peripheral sensoryNerve fibers

A

A

C

Largefibers

Smallfibers

There are Two Sensory AfferentNeurons

1. Large myelinated A fibers Very fast conduction velocity

Respond to innocuous stimuli2. Small myelinated A & C unmyelinated

fibers

Slow conduction velocity Respond to noxious stimuli


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Small-fiber sensory Large-fiber sensory Autonomic

-Burning pain

-Allodinia

-Hyperalgesia

-Hyperesthesia

-Paresthesia/dysesthesia

-Lancinating pain-Loss of pain &temp.

sensation

-Foot ulceration

-Loss of visceral pain

-Loss of vibration

-Loss of

proprioception-Loss of reflexes

-Slowed NCV

-Heart rateabnormalities

-Posturalhypotension

-Abnormal sweating

-Gastroparesis

-Neuropathic

diarrhea-Impotence

-Retrogradeejaculation


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Nociceptive afferentfiber

Normal Nerve Impulses Leadingto Pain

Noxiousstimuli Descendi

ngmodulati

on

Ascendi

nginput

Spinal

cord

Perceivedpain


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Nociception

Spinothalamic

tract

Peripheral

nerve

DorsalHorn

Dorsal rootganglion

Pain

Modulatio

n

Transduction

Ascendinginput

Descending

modulation

Peripheral

nociceptors

Trauma

Adapted from Gottschalk A et al.Am Fam Physician. 2001;63:1981, and Kehlet H et al.Anesth Analg. 1993;77:1049.

Perception

Transmission


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What is Inflammatory Pain?q Often classed along with acute pain as nociceptive,

refers to the spontaneous pain and tenderness feltwhen tissue is inflamed.

q Pain caused by injury to body tissues(musculoskeletal, cutaneous or visceral)

q Painful region is typically localized at the site of injury often described as throbbing, aching or stiffness .

q Usually time-limited and resolves when damagedtissue heals (e.g. bone fractures, burns and bruises)

q Can also be chronic (e.g. osteoarthritis, rheumatoidarthritis)

q Usually responsive to NSAIDs


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NOCICEPTIVE PAIN


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Prostaglandins

produced inresponse totissue injury;increasesensitivity ofnociceptor (pain)

Nociceptor thenreleases substance P,which dilates bloodvessels and increasesrelease ofinflammatorymediators, such as

Bradykinin (redness& heat)Substance P alsopromotesdegranulation of mastcells, which releasehistamine (swelling)

2

3

Pain-sensitive tissue

Painful stimulus

Prostaglandin

Substance P

Histamine

Mast cell

Bloodvessel

Bradykinin

Nociceptor

Substance P

2

3

1

Inflammation Tissue

1


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What is Neuropathic pain?

v Definition:

Pain arising as a direct consequence of a lesion or diseaseaffecting the somatosensory NERVE system

v Characterized by:

v Pain often described as shooting, electric shock-like or

burning.

v The painful region may not necessarily be the same as thesite of injury.

v Almost always a chronic condition (e.g. post herpetic

neuralgia, post stroke pain)v Responds poorly to conventional analgesics


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IASP Classifications:Peripheral Neuropathic and CentralNeuropathic Pain

Loeser JD, Treede RD. The Kyoto Protocol of IASP Basic Pain Terminology. Pain 2008;137:473-477.

Neuropathic pain

Pain arising as a direct consequenceof

a lesion or disease affecting thesomatosensory system

Peripheralneuropathic painPain arising as a direct

consequence ofa lesion or disease affecting the

peripheralsomatosensorysystem

Central neuropathic painPainarising as a direct consequence ofa lesion or disease affecting thecentralsomatosensory system


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Pathophysiology of Neuropathic Pain

NeP

Centralmechanisms

Peripheralmechanisms

PeripheralNeuron

hyperexcita

bility

Loss ofinhibitory

controlsCentral Neuron

hyperexcitability(central

sensitization)

Abnormal

Discharges


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Development of Neuropathic Pain

Woolf and Mannion. Lancet

Neuropathic pain

Spontaneouspain

Stimulus-evokedpain

Mechanisms

Metabolic Traumatic

ToxicIschemic

Hereditary

Compression

Infectious

Immune-related

Syndr

ome

Symptoms

Pathophys

iology

Etiology

Nerve damage due to:

Si d S t f N thi


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Signs and Symptoms of NeuropathicPain

Delayed, explosive response to any painful

stimulus

Hyperpathia2

Increased pain sensitivity e.g. pinprick, cold,heat

Hyperalgesia3

Painful in response to a non-nociceptivestimuluse.g. warmth, pressure, stroking

Allodynia3

Stimulus-evokedsymptoms

Abnormal, not unpleasant sensations e.g.tingling

Parasthesias2

Abnormal unpleasant sensationse.g. shooting, lancinating, burning

Dysesthesias2

Persistent burning, intermittent shock-like orlancinating pain

Spontaneouspain1

Spontaneoussymptoms

Description (example)Sign/Symptom

1. Baron. Clin J Pain. 2000;16:S12-S20.2. Merskey H et al. (Eds) In: Classification of Chronic Pain: Descriptions of Chronic Pain Syndromes and Definitions of Pain Terms.1994:209-212.


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The Inter-Relationship BetweenPain, Sleep, and Anxiety / Depression

Nicholson and Verma. Pain Med. 2004;5 (suppl.

Pain

Sleepdisturbances

Anxiety &Depression

Functionalimpairment


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Hyperalgesia & Allodynia

Gottschalk A et al.Am Fam Physician.

Injury

Pain

Intensit

y

1

0

8

6

4

Stimulus

Intensity

Normal

PainRespo

nse

Allodynia

Hyperalgesia

Hyperalgesiaheightened sense ofpain to noxious stimuli

Allodyniapain

resulting fromnormally painlessstimuli


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Normal

PeripheralTissue and

Nerves

FUNCTIONAL PAIN

AbnormalCentral

Processin

Spontaneous PainPainHypersensitivity

Brain


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Heat

Cold

Intense

Force

Mechani

cal

Heat

Cold

PainAutonomicResponse

Witdrawal Reflex

Nociceptor sensoryneuron

NOCICEPTIVE PAIN

Noxius PheripheralStimuli

Spinalcord

Brain


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Macrophage

NeutrophilGranulocyte

Tissue

Damage

Spontaneous PainPain Hypersensitivity

ReducedThreshold : Allodynia

IncreasedResponse : Hyperalgesia

Nociceptor sensoryneuron

INFLAMMATORY PAIN

Inflammation

Spinalcord

Mast Cell

Brain


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Spontaneous PainPainHypersensitivity

Peripheral NerveDamage

NEUROPATHIC PAIN

Spinalcord

Injury

Brain


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Three broad categories of free endings orreceptors are recognized:

Mechanoreceptors A- and C fibers

Thermoreceptors C fibers.

polymodal nociceptors majority of C fibersnoxious or tissue-damaging stimuli

mechanical

Thermal

chemical mediators (inflammation)


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The 3L Approach to Diagnosis

LISTEN

LOCATE LOOKNervous system

lesion / dysfunctionSensory

abnormalities,pattern recognition

Patient verbal descriptors,Q & A


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Pain Assessment Scales

Uni-DimensionalScale

Multi-DimensionalScale Only measures pain

intensity

Appropriate for acutepain

The most commonscale used inoutcome assessment(Analgesic efficacy)

Both intensity(severity) andunpleasantness(affective)

Appropriate forchronic pain

Research/pathophysiology Should be used in

clinical outcomeassessment

Verbal Rating Scale (VRS)None, mild, moderate,

severeNumeric Rating Scale

(NRS)Visual Analo Scale VAS

McGill Pain Questionnaire(MPQ)The Brief Pain Inventory

(BPI)The Memorial Pain


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Uni-Dimensional Pain AssessmentScales


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Ph t hi /N i P i S l


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Photographic/Numeric Pain Scale


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Multi-Dimensional Pain

Assessment Scales


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Quicker and easier

Well establishedreliability in cancer,arthritis, and AIDs.

Sensory, affectiveand functionalstatus

Useful fortreatment response

Takes up to 15 min

Good choice forpatients withprogressive disease

Worst

Lea

st

Average

RightNow

Treatment

Relief

GeneralActivity

Mood

Walkingability

Normalwork

Relation withother people

Sleep

Enjoymentof life


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Rapid: Sensory and affective Reliable in Cancer

ID PAIN S i l h l


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ID PAIN : Screening tool to helpdifferentiate nociceptive fromneuropathic pain

Neuropathic pain screening questionnaire

A multicenter study

Patients (N = 586) with non-headache chronic painA second multicenter study (N = 384) evaluated

reliability and validity.

89-item questionnaire 6 items

ID Pain appeared to accurately indicate thepresence of a neuropathic component of pain (c74,2%)

Portenoy R et al. Curr Med Res Opin. 2006 Aug;22(8):1555-65.


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Mark Yes to the following items that describe your


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Mark Yes to the following items that describe yourpain over the past week andNo to the ones that do not.

If patients have more than one painful area,they are to consider the one area that is most

relevant to them when answering the ID Pain


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Location: Patient ornurse marks drawing

Intensity: Patient ratesthe pain. Scale Used:

Quality: Use patints words, e.g. prick,ache, burn, sharp, hot etc.

Onset, duration, variations,rhythms (spontaneus orevoked):Manner of

expressingWhat

(Pain

Behaviou

Wh t


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What causes orincreases thepain?Effect of pain: (Note decreasedfunction, decreased quality of life)

Othercommen

ts:Plan:

Accompanying symptoms(eg nausea)SleepAppetitePhysicalactivityRelation with others (egirritability)Emotion (eg anger,suicidal, crying)ConsentrationOther


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Past Medical History

1.Medical related problems

2.Problems potentially affect the choice ofpain treatments?

3.Prior or current substance abusehistory?


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Current Medications

1.Dosage and pattern of use

2.Effectiveness

3.Drug tolerance


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Acute Pain (McQuay & Moore, 1999)TREATMENT

METHODSRemove the

causeOf pain

Medication

Regional

analges

ia

Physicalmethods

Psychological

approach

esSurgerySplinting

Low TechNerve blocksLocalanaesthetic

opioid

HighTechEpiduralinfusion

Localanaesthetic

physiotherapymanipulation

TENSAcu unct

relaxati

onpsychopro-phylaxis

hypnosis

Non-opioidAspirin &othersNSAIDS

Paracetamolcombination

OpioidMorphineothers


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ACUTE AND SEVERE

PAINRecommendedInitial Dosing

TraditionalInitial Dosing No Analgesia

Some Analgesia

Pain/AnalgesiaThreshold

SignificantSedation

SignificantToxicity

Analgesic

ANALGESIC MEDICATIONS


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ANALGESIC MEDICATIONS

PRIMARY ANALGESICS

Acetminophen

Prostaglandin synthesis inhibitors

Salicylates

Traditonal NSAIDs

COX-2-selective NSAIDs (coxibs)

Tramadol

Opioids

Traditional

Mixed

ADJUVANT MEDICATIONS

Antidepressants


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Chronic Pain (McQuay & Moore, 1999)

TREATMENT METHODS

Analgesics Block nervetransmission

Alternatives

Conventional

NSAIDParasetamolto opioid

Unconventionalantidepressant

anticonvulsantothers

ReversibleLocalanaesthetic

steroid

IrreversiblesurgeryNerve

destruction

Stimulators

AcupunctureHypnosisPsychology


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Update in Pain Management

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