various methods to assess pain, nerve condution studies

1. ASSESSMENT OF PAIN
BY
DR.SANDEEP

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

3. 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.

4. 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.

5. Pain and Disability
Nociception
Disability
Pain
Other physical symptoms
Physical impairment
Neuropathic Psychologic Social isolation
mechanisms processes Family distress
Sense of loss or inadequacy

6. ASSESSMENT OF PAIN

7. Why assess:
Beyond Codes of Ethics
Beyond regulatory requirements
 Determine ability to participate
 Ensure safety
 Diagnose
 Monitor progress
 Intervention modification
 Pain control/modification

8. 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

9. 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.

10. PAIN ASSESSMENT SCALES
UNIDIMENSIONAL SELF REPORT SCALES
Very simple,
Useful
Valid method to assess

11. VERBAL DESCRIPTOR SCALES
Five word scaling
MILD
DISCOMFORTING
DISTRESSING
HORRIBLE
EXCRUCIATING
DISADV:
Limited selection of descriptors
Pt. tend to select moderate grades than
extremes.

12. 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

13. 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

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

15.  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
o ADV:
 Average children as young as 3 yrs can use it.

16. Issues
Some patients have difficulty using
Not good for non verbal patients
Some patients will rate higher than 10:
Credit :http://hyperboleandahalf.blogspot.com/2010/02/boyfriend-doesnt-have-ebola-probably.html

17. PAIN ASSESSMENT TOOLS
UNIDIMENSIONAL SELF REPORT
SCALES
VERBAL DESCRIPTOR SCALE
VERBAL NUMERIC RATING SCALE
VISUAL ANALOG SCALE (VAS)
WONG-BAKER FACIAL PAIN RATING
SCALE

18. MULTIDIMENSIONAL INSTRUMENTS
• Provides more complex information about pt pain
• For assessing chronic pain
• Time consuming (used in research settings)

19. 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

20. 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

22. 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.

26.  PAIN ASSESSMENT TOOLS
 UNIDIMENSIONAL SELF REPORT SCALES
VERBAL DESCRIPTOR SCALE
VERBAL NUMERIC RATING SCALE
VISUAL ANALOG SCALE (VAS)
WONG-BAKER FACIAL PAIN RATING SCALE
 MULTIDIMENSIONAL INSTRUMENTS
McGILL PAIN QUESTIONARRE (MPQ)
BRIEF PAIN INVENTORY (BPI)
MASSACHUSETT’S GENERAL HOSPITAL PAIN
CENTER PAIN ASSESSMENT FORM(MGHPCPAF)

27. 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.

28.  PAIN ASSESSMENT TOOLS
 UNIDIMENSIONAL SELF REPORT SCALES
VERBAL DESCRIPTOR SCALE
VERBAL NUMERIC RATING SCALE
VISUAL ANALOG SCALE (VAS)
WONG-BAKER FACIAL PAIN RATING SCALE
 MULTIDIMENSIONAL INSTRUMENTS
McGILL PAIN QUESTIONARRE (MPQ)
BRIEF PAIN INVENTORY (BPI)
MASSACHUSETT’S GENERAL HOSPITAL PAIN
CENTER PAIN ASSESSMENT FORM(MGHPCPAF)
 PAIN DAIRIES

29. 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

30. PAIN ETIOLOGY:
by asking complete history and
if pain is –super ficial/peripheral/visceral
- localised/referred
Cause can be known

31. 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

32. SPECIFIC PAIN EVALUATION
History 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

33. NEUROLOGICAL EXAMINATION:
MENTAL FUNCTION:
Patient orientaion to time, place, person
Short term, long term memory
Choice of words used to descirbe symptoms and
answer questions
Educational background
CRANIAL NERVES:
If pt c/o head, neck, shoulder pain
SPINAL NERVE FN:
Light touch, sharp pain & propriception
DTR±, BIBINSKI±

34. COORDINATION:
Balance, rapid hand movement, finger nose test,
knee heel test, rhomberg test, gait
SENSORY SYSTEM
Routine sharp and dull sensation
Mechanical and thermal allodynia
Summation and after sensation
Hyperalgesia and hyperpathia

35. 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

36. MUSCULOSKELETAL SYSTEM
EXAMINATION
Usually evident on inspecting pt. posture and
muscular symmetry
Muscular atrophy – disuse
Flaccidity – 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

37. 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

38.  Pt personality influences his/her response to
pain & choice of the coping strategy.
few pts use strategies of control- distraction
and relaxation
anxious pts use high dose of analgesics
 Pt with chronic pain-depressed mood, sleep
disturbance, decreased activity,
preoccupation with somatic symptoms,
decreased libido and fatigue

39.  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.

40.  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

41. PEDIATRIC PAIN ASSESSMENT
SCALES DO NOT ALWAYS REPRESENT MULTIDIMENSIONAL ASPECT OF PAIN

42. 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)

43. 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.

44.  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)

45.  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.

47.  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

48. 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)

49. 7 - 11 YEARS
 Logic and reasoning
far more developed
 Imagination and
creativity
 Finalism and
concept of death
 Number pain scale
(scale 1-10)

50. 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

51.  NON-VERBAL CHILDREN
FLACC Scale
SCORING
CATEGORIES 0 1 2
FACE No particular Occasional grimace or Frequent to constant
expression or smile frown, withdrawn and frown, quivering chin
disinterested and clenched jaw
LEGS Normal position or Uneasy ,restless Kicking or legs drawn
relaxed tensed up
ACTIVITY Lying quietly, normal Squirming, shifting Arched, rigid or jerking
position, moves easily back and forth, tense
CRY No cry (awake or sleep) Mourns or whimpers Crying steadily,
Occasional complaints screams or sobs,
frequent complaints
CONSOLABILITY Content , relaxed Reassured by Difficult to console or
occasional touching, comfort
hugging or being
talked to: distractible

53.  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.

54. DIAGNOSTIC TESTS
 Radiograph:
#,metastasis,stenosis,osteophytes etc.
 C.T: B0ny lesions
 MRI: Soft tissue lesions
CNS Infarcts, plaques of demyelination
 DIAGNOSTIC BLOCKS
Somatic pain decreases
Central pain persists
helps in diagnosis of complex regional pain
syndrome(CRPS).

55.  DRUG CHALLENGES
To predict drug treatment utility
Helps in assessment of pain etiology
Eg:- 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

56.  NEUROPHISIOLOGIC TESTS
 THERMOGRAPHY
Increase in temp. in inflamed tissues
 MYELOGRAPHY
Injection of radio opaque dye into SAS for
seeing disc herniation, nerve root
impingement , arachnoiditis, spinal stenosis
DISADV:
Post dural puncture head ache
Meningeal irritation

57.  BONE SCANNING:
Radio active compounds accumulate in
the areas of bone growth / turn over
 SKIN BIOPSIES:
Immuno-labeled to show cutaneous nerve
endings
painful neuropathic conditions are
associated with loss of nociceptive
innervation in the painful regions of the skin

58.  FUNCTIONAL BRAIN IMAGING
(PET,FUNCTIONAL MRI):-
Provocative findings about cortical &
subcortical processing of pain information
FMRI shows pain remarkably distributed at the
cortical level.

60. 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.

61. ELECTRODIAGNOSTIC TESTING(EMG)
 To diagnose PNS disorders
 Normal value indicates
defect in CNS or Small
Fiber Neuropathy
 It has two components
NERVE CONDUCTION
STUDIES (NCS)
NEEDLE ELECTRODE
EXAMINATION (NEE)
 Helps in determining
severity of a lesion and
prognosis

62. NERVE CONDUCTION STUDIES
 Electrical stimulation of nerve – measure
response in nerve itself / muscle
 Types
Motor
Sensory
 Additional type of study – “late response” –
appearance of a characteristic wave (F) and a
reflex (H)

63.  Parameters to be assessed:
Amplitude of the response – no. of intact neurons
Latency
Nerve conduction velocity integrity of myelin sheath

64.  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

65.  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

68. 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

69. FINDINGS IN MUSCLE INJURY
 Relaxed 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)

70.  Activated muscle:
o Size and shape of motor units & their firing patterns
assessed
 Denervated muscle:
o Motor units reduced in number but fire excessively fast
(REDUCED REQUIREMENT)

71. FINDINGS IN MUSCLE INJURY
 Myotonic Dystrophy:
o Large no. of motor fibers fire at a normal rate despite
minimal force production(EARLY RECRUITMENT)
 Chronic neuropathy:
o Motor units are excessively large
 Myopathic disorders:
o Motor units are smaller than normal

72. FINDINGS IN NERVE INJURY
 Axonal nerve injury/Neuropathy:
o NCS : reduced sensory & motor amplitudes
o NCV : slightly slow
o In mixed nerve injury sensory affected more than motor
 Demyelinating neuropathies:
o NCV slowed
o Distal latencies & F wave latencies- prolonged
 NEE:
o Decreased recruitment and rapidly firing motor units
o Axonal nerve:fibrillation potentials & other spont activity +
o Chronic axonal neuropathy: reinnervation produces motor
unit remodeling so that other motor units increase in size

73.  TIMING:
more than 3 weeks after injury(wallerian
degeneration must occur)
after acute axonal damage
CMAP amplitude begin to
decrease at 3 days, peaks 7 days
SNAP amplitude begins to
decrease at 7 days , peaks 11 days

74. 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%

75.  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

76.  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.

77. 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

79. 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

80. 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)

82. 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

83. 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

84.  USES:
• Isolate nerve root pathology
• Low CPT(current perception threshold)-
inflmn/neuritis
• Elevated CPT-neuropathy/loss of nerve function

85. AUTONOMIC TESTING
 ANS dysfunction is usually due to small fiber
sensory neuropathy
 EMG is Normal.

86. SUDOMOTAR FUNCTION:
 Testing sympathetic pathways involved in
sweating
 Sympathetic Skin Response:
simple, less reliable, using EMG
intersubject variability & habituation of the
response with repetitive stimuli- absence of
response-abnormality

87.  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

88.  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

89. 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.

90. 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