Pain Perception and Chronic Pain

1
Pain Perception and Chronic Pain

• Tara Jo Manal PT, OCS, SCS

2
Epidemiology

• 97 causes are unknown
• 2 are disk
• 1 Facet
• 30 require conservative management
• 1 surgery
• All others recover spontaneously

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Epidemiology

• 30 workers miss time due to back injury
• 2-4 change jobs as a result
• Workers off work gt6months have 50 chance of
  returning
• Decreases to 25 after 1 year
• 88 first time injury pain-free in 6 wks
• 98 in 24 weeks
• 99 in 52 weeks

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Nonorganic Signs

• 3 or more are considered test
• Regional Disturbance- Sensory or motor
  changes/weakness that is nonanatomical
• Superficial/nonanatomic tenderness
• Light touch or deep tenderness over a widespread
  area, nonanatomic

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Nonorganic Signs

• Simulation
• Axial Loading
• Low back pain reported with pressure on the
  patients head while standing

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Nonorganic Signs

• Simulation
• Rotation
• Pain in the low back when the shoulders and
  pelvis are rotated in the same plane as the
  patient stands

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Nonorganic Signs

• Distraction
• Straight Leg Raising
• Inconsistent limitation of straight leg raising
  in supine and seated positions

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Nonorganic Signs

• Overreaction
• Disporportinate verbalization, facial
  expressions, muscle tension, collapsing,
  sweating, during the examination

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Nonorganic Symptom Descriptors

• Do you get pain in your tailbone?
• Do you have numbness in your entire leg (front,
  side, and back) at the same time?
• Do you have pain in your entire leg (front, side,
  and back) at the same time?

• Does your whole leg give way?
• Have you had any time during this episode when
  you have very little back pain?
• Have you had to go to the ER due to back pain?
• Has all treatment for your back pain made you
  worse?

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Abnormal Illness Behavior

• Maladaptive overt illness related behavior which
  is out of proportion to the underlying physical
  disease and more readily attributable to
  associated cognitive and affective disturbances

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Purpose of Nonorganic Testing

• When the test is negative they can rule out
  abnormal illness behavior
• Not intended to rule in only identify those at
  risk for an unsuccessful treatment outcome
• Fritz 2000 Acute LBP
• 2 or more signs
• 3 or more symptoms
• Increase likelihood of not returning to work by
  6-10

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Psychosocial Variables in LBP

• Bigos et al 1986
• Boeing plant in Washington
• Analyzed 4645 injuries (900LB) over 15months
• Correlation between back injury and poor
  appraisal ratings (6 mo before injury)
• Designed prospective study to look at 3020
  employees.. 279 developed back injury

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Psychosocial Variables in LBP

• Psychosocial Factors
• Personality Inventories
• Family Support
• Co-worker support
• Job satisfaction

• Personal Factors
• Isometric strength
• Flexibililty
• Aerobic Capacity
• Height
• Weight

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Psychosocial Variables in LBP

• Psychosocial Factors (job employment) had
  strongest influence
• Poor satisfaction 1.85 times more likely to
  report a back injury
• 15 variance explained by Job Satisfaction
• 85 unaccounted for (not job satisfaction)
• Marras 1993- 400 repetitive lifting jobs in 48
  industries (1.56 odds ratio for job satisfaction)

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Psychosocial Variables in LBP

• Marras 1995
• 400 lifting jobs classified as low, medium, or
  high risk jobs
• 5 measures reflected the classification
• Maximum load moment, maximum lateral trunk
  angular velocity, average trunk twisting
  velocity, lifting frequency, maximum saggital
  trunk angle)
• Saw job satisfaction 1.32 1.48 but the measures
  above could predict 10times more likely to be
  injured

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Psychosocial Variables in LBP

• Norman 1998
• Auto plant- 104 cases and 130 random controls
• Biomechanical data, psychosocial, and
  psychophysical (perceived stresses)
• Factors
• Peak lumbar shear force 1.7
• Lumbar disc compression over shift 2.0
• Poor workplace social environment 2.6
• Higher job satisfaction 1.7

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Psychosocial Variables in LBP

• Factors
• Higher coworker support 1.6
• Perception of being more educated 2.2
• Perception of higher physical exertion 3.0
• Capacity of worker relative to job
• 45 of variance is explained by these factors
• 12 psychosocial factors
• 31 biomechanical
• Body mass index 2.0
• Prior compensation claim 2.2

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Chronic Pain and Disability

• Mendelson 1982 LBP persists after legal
  settlement
• Hadler 1991 relationship between medical
  examiner determining reward and patient cases the
  patient to act disabled
• Werneke and Hart 2001- pain patterns that
  centralize or not are more predictive of
  chronicity than psychosocial factors

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Chronic Pain

• White and Gordon 1982
• 85 of disabling LBP cases have no definitive
  pathoanatomical diagnosis
• LBP patients have nonorganic signs suggesting
  psychological disturbances
• Poor diagnostic techniques make solid diagnosis
  difficult

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Biomechanical and Psychosocial Factors

• Psychological and Pain are linked
• Marras 2000
• Personality and psychosocial factors increase
  spinal loads by up to 27
• Muscular co-contraction
• Seen at moderate lifting loads, at heavy loads
  gone

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First-time Injury Risk Factors

• Best indicator of back trouble is previous back
  trouble (60)
• Police officers
• Body armor is increased risk
• Greater than 2hrs in car is increased risk
• Falls
• Longer sick time and greater recurrence than
  other types of first-time LBP
• Age and Gender
• Females sustain 2/3 load males
• 60year old sustain 2/3 of 20 year old
• 35female in heavy loads and 19 males

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First-time Injury Risk Factors

• Increased joint mobility and decreased lumbar
  endurance affected first time LBP
• Vibration( esp. sitting)
• Remaining sedentary
• 8 increase white collar
• 14 decrease for blue collar
• Static work postures
• Esp. mild trunk flexion 20-45
• Frequent bending and twisting
• Spine motion not torso
• Lifting
• Pulling
• Pushing

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Chronic Changes After Injury

• Muscular Function
• Delayed onset of trunk muscles to sudden activity
• Anatomical changes
• Multifidus atrophy
• Muscular Imbalance
• Increased BMI
• Flexor/Extensor Ratio
• Lateral Bend Endurance
• Loss Flexion ROM

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Biomechanics and Psychosocial Factors

• Biomechanical Factors are associated with LBP
• Psychosocial Factors play role and may related
  more to episodes after initial
• The 2 influence each other
• LB tissue damage can initiate a cascade of
  changes that can cause pain and intolerance for
  years
• Many times of damage are not detected and others
  are over interpreted

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Chronic Pain

• Emotional distress
• Depression
• Failed Treatment
• Adoption of a sick role
• Self-sustaining condition

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Pain Models

• Nociception
• Pain
• Suffering
• Pain Behavior

• Physical Problem
• Distress
• Illness Behavior
• Sick Role

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Fear Avoidance

• Pain perception
• Sensory
• Emotional
• Synchronous and Proportional
• Disassociation
• Pain is out of proportion to injury
• Patient fears pain and avoids it

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Fear of Pain

• Stressful life events
• Personality
• Previous pain history
• Normal pain coping strategy
• Confrontation resumes activity as tolerated
• Avoidance of activities that may cause pain

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Fear Avoidance Belief Questionnaire

• FABQ
• 16 Items 0-6 (higher avoidance)
• 7 Item work subscale
• My work might harm my back
• 4 Item physical activity subscale
• I should not do physical activity that might make
  my pain worse

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Fear Avoidance Belief Questionnaire

• FABQ
• No difference found between cervical and lumbar
• Patients with cervical spine disorder had weaker
  relationships with pain and disability than
  lumbar
• Differences seen with gender, symptom onset and
  payer type

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Fear Avoidance Belief PT

• Educate the patient LBP is a common condition not
  a serious disease
• Back Book
• Graded Exercise
• Those with higher Fear Avoidance Belief benefit
  from FABPT

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Depression

• Depressed mood most of the day, nearly every day
• Markedly diminished interest or pleasure in
  almost all activities most of the day, nearly
  every day (as indicated by either subjective
  account or observation by others of apathy most
  of the time)
• Significant weight loss or gain
• Insomnia or hypersomnia
• Psychomotor agitation or retardation
• Fatigue (loss of energy)
• Feelings of worthlessness (guilt)
• Impaired concentration (indecisiveness)
• Recurrent thoughts of death or suicide