BY DR.SANDEEP

ASSESSMENT OF PAIN

PAINDEFINITION:

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage

INTRODUCTION

There is no objective measurement of pain.

The pain history is the key to assess it & includes patient description of pain intensity, quality, location, timing, duration and aggravating and relieving factors.

INTRODUCTION

Diagnosis and assessment of Acute pain requires frequent and consistent assessment as a part of daily clinical care to ensure rapid titration of therapy & preemptive intervention.

Chronic pain is often more diagnostically challenging . Structured history and clinical examination will define treatable problems.

Pain and Disability

Nociception

Other physical symptomsPhysical impairment

Neuropathic Psychologic Social isolationmechanisms processes Family distress

Sense of loss or inadequacy

Pain

Disability

ASSESSMENT OF PAIN

Why assess:

Beyond Codes of EthicsBeyond regulatory requirements

Determine ability to participate Ensure safety Diagnose Monitor progress Intervention modification Pain control/modification

Hierarchy of Pain Assessment Techniques

A. Self Report B. Search for Potential Causes of Pain:

A change in behaviour requires careful evaluation of the possibility of additional sources of pain.

C. Observe Patient Behaviours: In the absence of self report, observation of patient behaviouris a valid approach to pain assessment. Not always accurate reflections of intensity and may indicate another source of distress

D. Surrogate Reporting

ASSESSMENT OF PAIN

PAIN HISTORY: General medical history Specific pain history (intensity,

location, pathophysiology, etc,..

PAIN ASSESSMENT TOOLS No objective measurement

Intensity of pain is the most difficult and frustrating

characteristics of pain to pinpoint

Few scales and tests are available.

PAIN ASSESSMENT SCALES

UNIDIMENSIONAL SELF REPORT SCALES

Very simple, Useful

Valid method to assess

VERBAL DESCRIPTOR SCALES

Five word scaling

MILDDISCOMFORTINGDISTRESSINGHORRIBLEEXCRUCIATING

DISADV:

Limited selection of descriptorsPt. tend to select moderate grades than extremes.

VERBAL NUMERIC RATING SCALE

On a numeric scale 0 to 10

0-no pain

10-worst pain imaginable

ADVANTAGES:• Simplicity, reproducibility, easy comprehensibility• Sensitivity to small changes in pain• Children at 5 years, who can count and have concept

about numbers can use this scale

VISUAL ANALOG SCALE(VAS)

Similar to verbal numerical scale

except that the pt. marks on a measured line, one end of which is labeled NO PAIN and other end WORST IMAGINABLE PAIN, where the pain falls

• More valid for research purposes• Less used-more time consuming /

requires motor control

WONG – BAKERS FACIAL PAIN RATING SCALE• Evaluating pain in children is difficult as they cannot describe the pain

Each facial feature is given a number 0 to 5

happy smiling face to a sad, teary face

To extrapolate this scale to the VAS, the value chosen is multiplied by two

oADV: Average children as young as 3 yrs

can use it.

IssuesSome patients have difficulty usingNot good for non verbal patientsSome patients will rate higher than 10:

Credit :http://hyperboleandahalf.blogspot.com/2010/02/boyfriend-doesnt-have-ebola-probably.html

PAIN ASSESSMENT TOOLS

UNIDIMENSIONAL SELF REPORT SCALESVERBAL DESCRIPTOR SCALEVERBAL NUMERIC RATING SCALEVISUAL ANALOG SCALE (VAS)WONG-BAKER FACIAL PAIN RATING

SCALE

MULTIDIMENSIONAL INSTRUMENTS

• Provides more complex information about pt pain

• For assessing chronic pain

• Time consuming (used in research settings)

McGILL PAIN QUESTIONNAIRE (MPQ)

• Most frequently used multidimensional test

• Descriptive words from three major dimensions of pain (sensory, affective, evaluative) are further sub-divided into 20 sub-classes each containing words of various degrees

• 3 scores are obtained one from each dimension and total score is calculated

• Reliable and used in clinical research

BRIEF PAIN IN VENTORY (BPI)

• Patients are asked to rate the severity of their pain at its “worst “,”least” or “average” within the past 24 hrs. and at the time the rating is done.

• It also requires the patient to represent the location of their pain on a schematic diagram of the body

• BPI correlates with activity, sleep and social interaction.

• It is cross cultural and a useful method for clinical study

MASSACHUSETT’S GENERAL HOSPITAL PAIN CENTRE PAIN ASSESMENT FORM (MGHPCPAF):

• It combines many of the foregoing assessment instructions & is given to all pts on initial consultation at their hospital

• Elicits information about pain, therapies tried, post &present medications

DISADV:Time consuming & not applicable

if there are language constraints.

PAIN ASSESSMENT TOOLSUNIDIMENSIONAL SELF REPORT SCALES

VERBAL DESCRIPTOR SCALEVERBAL NUMERIC RATING SCALEVISUAL ANALOG SCALE (VAS)WONG-BAKER FACIAL PAIN RATING SCALE

MULTIDIMENSIONAL INSTRUMENTSMcGILL PAIN QUESTIONARRE (MPQ)BRIEF PAIN INVENTORY (BPI)MASSACHUSETT’S GENERAL HOSPITAL

PAIN CENTER PAIN ASSESSMENT FORM(MGHPCPAF)

PAIN DAIRIES:

• Helps in evaluating the relationship b/w pain and daily activity

• Pain can be described using Numerical Rating Scale, during activities(walking, standing, sitting& routine works)

• Evaluation done on hourly basis• Use of medications & alcohol &

emotional response of pt can also be recorded

• It reflects pt pain more accurately than a retrospective description.

PAIN ASSESSMENT TOOLSUNIDIMENSIONAL SELF REPORT SCALES

VERBAL DESCRIPTOR SCALEVERBAL NUMERIC RATING SCALEVISUAL ANALOG SCALE (VAS)WONG-BAKER FACIAL PAIN RATING SCALE

MULTIDIMENSIONAL INSTRUMENTSMcGILL PAIN QUESTIONARRE (MPQ)BRIEF PAIN INVENTORY (BPI)MASSACHUSETT’S GENERAL HOSPITAL

PAIN CENTER PAIN ASSESSMENT FORM(MGHPCPAF)

PAIN DAIRIES

PAIN LOCATION:• Location and disrtibution of pain helps in

understanding the pathophysiology of pain• Is pain localised/referred• Is pain superficial/peripheral/visceral

Visceral afferent information converge with superficial afferent input at the spinal level, referring the perception of visceral pain to a distant dermatome

PAIN ETIOLOGY:

by asking complete history and if pain is –super

ficial/peripheral/visceral - localised/referred

Cause can be known

PHYSICAL EXAMINATION

GPE• Head to toe examination• Main things are • Appearance –obese, emaciated,

histrionic, flat affect• Posture- splinting, scoliosis, kyphosis• Gait- antalgic, hemiparetic, using

assistive devices• Expression- grimacing, tense,

diaphoretic, anxious• Vital signs- sympathetic over activity

SPECIFIC PAIN EVALUATIONHistory directs the search for physical findings

• Skin: color change, flushing, edema, hairloss, presence or absence of sweating

• Nails: dystrophic changes• Nerve root injury-goose flesh (cutis

anserina) in affected dermatome• Palpation allows mapping of painful areas,

detection of change in intensity of pain and defines pain type & trigger points

• Pt response is noted(verbal/non-verbal)• Also identifies any changes in sensory

modality & pain processing which may manifest as anesthesia /hypesthesia/analgesia

NEUROLOGICAL EXAMINATION:MENTAL FUNCTION:Patient orientaion to time, place, personShort term, long term memoryChoice of words used to descirbe

symptoms and answer questionsEducational background

CRANIAL NERVES:If pt c/o head, neck, shoulder pain

SPINAL NERVE FN:Light touch, sharp pain & propriceptionDTR±, BIBINSKI±

COORDINATION:

Balance, rapid hand movement, finger nose test, knee heel test, rhomberg test, gait

SENSORY SYSTEM

Routine sharp and dull sensationMechanical and thermal allodyniaSummation and after sensationHyperalgesia and hyperpathia

Dynamic allodynia – light rub finger tip/ foam/cotton

Static allodynia –slowly apply perpendicular pressure

Thermal allodynia – warm/cold test tube / tuning fork

Hyperalgesia –single pin prick, multiple pin prinks for summation / after sensation

MUSCULOSKELETAL SYSTEM EXAMINATIONUsually evident on inspecting pt. posture

and muscular symmetryMuscular atrophy – disuseFlaccidity – weakness / paralysis /

abnormal movement due to CNS / proprioceptive damage

Limited range of movement of major joints – pain / disc ds / Arthritis

Palpation of muscles - determines trigger points and evaluates range of motion

ASSESSMENT OF PSYCHOLOGICAL FACTORS:• Psychological aspects of pain• Effects of pain on behavior and emotional

stability

Use of descriptive pain questionnaire such as MPQ may provide some evidence of a pts affective response to pain

aching and tingling-sensory aspect of pain

agonising and dreadful- negative feelings

Pt personality influences his/her response to pain & choice of the coping strategy.few pts use strategies of control- distraction and relaxationanxious pts use high dose of analgesics

Pt with chronic pain-depressed mood, sleep disturbance, decreased activity, preoccupation with somatic symptoms, decreased libido and fatigue

MMPI(Minnesota Multiphasic Personality Inventory ) Grading may expand the assessment

Pt with chronic pain score very high on depression hysteria and hypochondriasis scales.

It reflects functional limitation, secondary to chr pain as well as psychological abnormality

Predisposing factors include:- Major Depression, Somatisation disorder, Conversion syndrome, Hypochondriasis, and psychogenic pain disorders.

Psychogenic pain: Multiple locations of pain at different

timings Pain problems dating since adolescence Pain without obvious somatic cause Multiple elective surgical procedures Substance abuse Social or work failure

PEDIATRIC PAIN ASSESSMENTSCALES DO NOT ALWAYS REPRESENT MULTIDIMENSIONAL ASPECT OF PAIN

BIRTH - 2 YEARS

Pain Perception

Neonates as young as 24-weeks feel pain

Ascending nerve tracts develop earlier than the pain inhibiting nerve tracts meaning that neonates may experience a greater intensity of pain than older children

Neonates exposed to repeated painful stimuli show increasing sensitivity

Neonatal/Infant Pain Scale(NIPS)

BIRTH - 2 YEARS (CONTINUED)

Cognition No “understanding” of pain and unable

to provide a self-report 12 to 18 months, beginning of reasoning

and language (1- or 2-word statements) Major cognitive processing through

senses (eyes, ears, hands) CHEOPS (1-7 years)

Looks at types of pain behavior: cry, facial, verbal, torso, touch and legs.

Neonatal Facial Coding System (NFCS) has been extensively applied to the neonatal pain studies

The responses of facial features, including brow bulge, eye squeeze, nasal-labial furrowing and mouth open are related with pain stimulus

Further extension is the multidimensional scoring systems, which combined facial expression with physiological parameters. These include premature infant pain profile (PIPP) neonatal infant pain scale (NIPS) , and Crying Requirement of oxygen supplementation, Increase of heart rate and blood pressure, facial Express, Sleeplessness (CRIES)

NIPS can only provide 1 or 0 index, which is difficult for quantitative comparison.

To provide a system for clinical studies of neonatal pain responses, Neonatal Facial Image Scoring System (NFISS) is introduced.

This results in the lowest score of 0 to highest score of 15 for graded pain responses.

Nociceptive stimulus can induce physiological and behavior changes in neonate

Heart rate, respiratory rate, oxygen saturation, sweating, cranial pressure, vagal tone, cortisol, and catecholamine have all been monitored as physiological parameters in pain responses

The behavior changes include voice volume (crying, weeping, moaning), facial expressions (brow bulge, eye squeeze, nasal-labial furrowing, mouth open, lip purse, stretch mouth, taut tongue, and chin quiver etc), posture (withdrawing, quivering, stiff, hand holding), alertness, feeding pattern, and interacting modes

2 - 4 YEARS

CNS fully developed Development of

autonomy continues Significant language

development Limited logic and

reasoning Self-centered thought

process Visual analog (Wong-

Baker Faces)

7 - 11 YEARS

Logic and reasoning far more developed

Imagination and creativity

Finalism and concept of death

Number pain scale (scale 1-10)

Adolescents (11+ years)

Cognitively adults Same pain assessment methods as adults

Abstract thinking and understanding hypothetical situations

Emotional needs Include them in the process

Respect their privacy Respect their pain reports

NON-VERBAL CHILDREN FLACC Scale

SCORING

CATEGORIES 0 1 2

FACE No particular expression or smile

Occasional grimace or frown, withdrawn and disinterested

Frequent to constant frown, quivering chin and clenched jaw

LEGS Normal position or relaxed

Uneasy ,restless tensed

Kicking or legs drawn up

ACTIVITY Lying quietly, normal position, moves easily

Squirming, shifting back and forth, tense

Arched, rigid or jerking

CRY No cry (awake or sleep)

Mourns or whimpers Occasional complaints

Crying steadily, screams or sobs, frequent complaints

CONSOLABILITY

Content , relaxed Reassured by occasional touching, hugging or being talked to: distractible

Difficult to console or comfort

Hospitals should use a standard pain scale for the various age groups to allow continuity.

Self report scores (e.g. numerical rating scale) can mislead. A score of 4 may denote severe pain to one adolescent while 8 may be severe to another.

Pain can be worsened by anxiety, depression and spiritual crisis. We must consider this in our assessment.

DIAGNOSTIC TESTS

Radiograph:#,metastasis,stenosis,osteophytes etc.

C.T: B0ny lesions MRI: Soft tissue lesions CNS Infarcts, plaques of demyelination DIAGNOSTIC BLOCKS

Somatic pain decreasesCentral pain persistshelps in diagnosis of complex regional

pain syndrome(CRPS).

DRUG CHALLENGESTo predict drug treatment utility

Helps in assessment of pain etiologyEg:- Brief iv infusion of opioid, lidocaine, phentolamine are used to • Predict opioid sensitivity in non

malignant chr pain• Sensitivity to Na channel block in

neuropathic pain• Assess the potential reversibility of

symptoms of components of pain

NEUROPHISIOLOGIC TESTSTHERMOGRAPHY

Increase in temp. in inflamed tissues

MYELOGRAPHYInjection of radio opaque dye into

SAS for seeing disc herniation, nerve root impingement , arachnoiditis, spinal stenosisDISADV:

Post dural puncture head acheMeningeal irritation

BONE SCANNING:Radio active compounds

accumulate in the areas of bone growth / turn over

SKIN BIOPSIES:Immuno-labeled to show

cutaneous nerve endingspainful neuropathic conditions

are associated with loss of nociceptive innervation in the painful regions of the skin

FUNCTIONAL BRAIN IMAGING (PET,FUNCTIONAL MRI):-

Provocative findings about cortical & subcortical processing of pain information

FMRI shows pain remarkably distributed at the cortical level.

THANK YOU

NEUROPHYSILOGICAL TESTING

It is useful because• Helps detect underlying pathology• Helps define pain mechanics• Helps anatomically localize pain instigators• Helps focus treatment on mechanics• Helps predict if pt. will respond to particular

treatment by clarifying mechanism• Used sequentially, helps monitor ds progressa nd

response to treatment• May have medico legal application• Advances pain research by providing quantitative &

reproducible measurements of pain & its various mechanics.

ELECTRODIAGNOSTIC TESTING(EMG) To diagnose PNS disorders Normal value indicates

defect in CNS or Small Fiber Neuropathy

It has two componentsNERVE CONDUCTION

STUDIES (NCS)NEEDLE ELECTRODE

EXAMINATION (NEE)

Helps in determining severity of a lesion and prognosis

NERVE CONDUCTION STUDIES

Electrical stimulation of nerve – measure response in nerve itself / muscle

Types MotorSensory

Additional type of study – “late response” – appearance of a characteristic wave (F) and a reflex (H)

Parameters to be assessed:Amplitude of the response – no. of intact

neuronsLatency Nerve conduction velocity integrity of

myelin sheath

MOTOR NCS: Stimulate

motor nerve and record Compound Motor Action Potential (CMAP) from belly of the muscle innervated.

Then stimulate the nerve proximally for conduction velocity

SENSORY NCS:

Stimulate sensory nerve and record Sensory Nerve Action Potential (SNAP)

Stimulate median nerve at wrist and record SNAP at digital nerve of second finger.

SNAP is smaller in amplitude than CMAP

NEEDLE ELECTRODE EXAMINATION Insert needle electrode in to muscle

belly and look for electrical activity at rest & on voluntary contraction

Used for the diagnosis of denervation / myopathic disorders

FINDINGS IN MUSCLE INJURYRelaxed muscle:

o look at INSERTIONAL ACTIVITY (response to small movements of electrodes)

o look for SPONTANEOUS MOVEMENTS (fasciculations, +ve sharp waves, fibrillation potentials, complex repetitive discharges, myotonic discharges)

Activated muscle:o Size and shape of motor units & their firing

patterns assessed

Denervated muscle:oMotor units reduced in number but fire

excessively fast (REDUCED REQUIREMENT)

FINDINGS IN MUSCLE INJURYMyotonic Dystrophy:

o Large no. of motor fibers fire at a normal rate despite minimal force production(EARLY RECRUITMENT)

Chronic neuropathy: oMotor units are excessively large

Myopathic disorders:oMotor units are smaller than normal

FINDINGS IN NERVE INJURY

Axonal nerve injury/Neuropathy:o NCS : reduced sensory & motor amplitudeso NCV : slightly slowo In mixed nerve injury sensory affected more than motor

Demyelinating neuropathies:o NCV slowedo Distal latencies & F wave latencies- prolonged

NEE:o Decreased recruitment and rapidly firing motor unitso Axonal nerve:fibrillation potentials & other spont

activity +o Chronic axonal neuropathy: reinnervation produces

motor unit remodeling so that other motor units increase in size

TIMING:more than 3 weeks after

injury(wallerian degeneration must occur)

after acute axonal damageCMAP amplitude begin

to decrease at 3 days, peaks 7 daysSNAP amplitude

begins to decrease at 7 days , peaks 11 days

QUANTITATIVE SENSORY TESTING Tests high threshold

pain and temperature sensing mechanisms.

Provides information about function of entire afferent pain pathway

Non invasive, simple, psychophysical tests

Increased diagnostic sensitivity 67 %to 100%

Common tests include: Thermal(warm, cool, hot, cold) mechanical: (light touch and pin prick) Vibratory and electrical stimuli

A delta- stimulated by cold perception & by HP&CP stimuli

C fibers- warm perception & by HP&CP

A beta- vibration

Painful neuropathies- Thermal hypesthesia; hyperesthesia; hypoalgesia;

hyperalgesia Peripheral sensitization - heat hyperalgesia

and inflammation- CRPS-I- cold/heat hyperalgesia

without hypesthesia/hyperesthesia

Central sensitization: tactile allodynia, mechanical hyperalgesia

Postherpetic neuralgia- thermal hypoesthesia & hyperalgesia(anesthesia dolorosa)

Sympathetically mediated changes in Sudomotor pain- reflex (QSART), sweat output, &

vasomotor fn.

THERMAL STIMULI

Pain and temp sensations are closely related as they are transmitted by small high threshold fibers(A delta and C )

Computer regulates the changes in temperature on a small surface electrode placed flat against skin

Thresholds measured are WS,HS,HP,CP

HP felt at 45C WS/CS felt at 1 / 2 C above or below

baseline

VIBRATION STIMULUS

Large A beta fibers Head of vibration device

must make solid, even, balanced contact

Extra pressure alters nerve function

Vibration range is 0 to 130 mic

Delivers at a rate of 0.1 to 4 mic/sec

MECHANICAL STIMULUS

Use of Von Frey Hairs (filaments) of graduated diameter

If pressed on skin hard enough to cause a bend, exert a reproducible and reliable calibrated force

Wt of filaments- 4.5 mg to 447 gms Expressed in terms of tension (

gm/cm ) or pressure (gm/sq cm)

o USES:• Changes in pain threshold(prim/second

hyperalgesia)• To test summation(seen in neuropathic

pain states-spinal cord injury/ post herpetic neuralgia)

• Nociceptive pain states(fibromyalgia, Tm jn disorders

• At least 8 repetitive pinpricks at same area with 2 to 3 sec gap causes escalation of discomfort- HYPERALGESIA

ELECTRICAL STIMULUS

5 Hz - C fibers 250 Hz – A beta fibers 2000 Hz – A delta fibers

Current can be delivered from 0.1 to 9.99 mA

USES:

• Isolate nerve root pathology• Low CPT(current perception threshold)-

inflmn/neuritis• Elevated CPT-neuropathy/loss of nerve

function

AUTONOMIC TESTING

ANS dysfunction is usually due to small fiber sensory neuropathy

EMG is Normal.

SUDOMOTAR FUNCTION:

Testing sympathetic pathways involved in sweatingSympathetic Skin Response:

simple, less reliable, using EMGintersubject variability & habituation of the response with repetitive stimuli- absence of response-abnormality

Quantitative Sudomotor Axon Reflex Test:

high sensitivity and reliability

A special sweat capsule is attached to skin & Ach is iontophorsed through skin to produce skin response

sweat is then collected in capsule and then quantified

Thermoregulatory sweat test:

Sensitive and Reliable

Powder that changes color when exposed to sweat is applied all over the body allowing areas of anhidrosis to be mapped

CARDIOVAGAL & ADRENERGIC FUNCTION:

HR response to deep breathing.

HR &BP response to Valsalva maneuver & head upright tilt- detected by Symp & Parasymp fn.

HR response to deep breathing determined by Parasympathetic function only.

Conclusions

Make an accurate diagnosis If you’re not sure, consider trial

of pain management Review patient goals Assess, treat, reassess, treat If unsuccessful, review type of

pain and history

THANK YOU