Chapter Two - Pain and Management

Question 1

There are 3rd order neurons to several areas of the brain. What are their roles?

Answer 1

• Planning
• Sensory discrimination
• Memory
• Emotion

Question 2

Describe the Gate Control Theory.

Answer 2

Possible brain modulation, not just a passive system• Includes descending pathways

Question 3

What are endorphins?

Answer 3

Endogenous opioids released within the brain and spinal cord

Question 4

What is the Neuromatric Theory?

Answer 4

Varied dimensions that overlap to create a unique experience

Question 5

What are the four components of pain?

Answer 5

Strength of Stimulus - the stronger the stimulus, the less the patient is able to tell where the pain is

Position of the Painful Structure - pain is referred distally

Depth from the Surface - more superficial lesioned tissue, the more precise is its

localizing ability
Nature of the Affected Tissue - nerve root versus peripheral nerve

Question 6

What is referred pain? Why do we have it?

Answer 6

WHAT: an error in perception by the sensory cortex in the brain as to the source of the painful stimulus (i.e., felt elsewhere than its true site)

WHY: cutaneous, visceral, and skeletal muscle nociceptors converge on a common nerve root of the spinal cord, but brain interprets as cutaneous (higher proportion)

Question 7

What is the difference between segmental and extrasegmental referred pain?

Answer 7

SEGMENTAL: pain referred to a structure within the same dermatome

EXTRASEGMENTAL: pain referred to >1 dermatome (multiple levelsàsevere)

Question 8

In one sentence, what is a dermatome?

Answer 8

An area of skin in which sensory nerves derive from a single spinal nerve root

Question 9

Where does the dermatome project? Where can pain refer alon a dermatome? In what direction, usually?

Answer 9

Projects more distally than the key muscle (myotome)

Dermatome and key muscles develop from the same segment

Any structure within a particular segment can refer pain to the same dermatome of that segment

It may refer along the whole length of the dermatome or only part of it

Pain is generally referred in a distal direction, thus the structure at fault will be located proximal to where the patient feels the pain

Question 10

What is root pain? Is all root pain referred? Is all referred pain root pain?

Answer 10

Irritation of nerves and nerve roots

Deep, sharp and well localized

All root (radicular) pain is referred, but not all referred pain is root pain

Question 11

What is acute pain? Give examples. What is its role?

Answer 11

Results from injury or disease that causes, or can cause, tissue damage

E.g., infection, trauma, metabolic disorder progression, degenerative disease

Protects against further tissue damage

Question 12

Results from injury or disease that causes, or can cause, tissue damage

E.g., infection, trauma, metabolic disorder progression, degenerative disease

Protects against further tissue damage.

What kind of pain is this?

Answer 12

Acute pain

Question 13

What is subacute pain? What is its purpose?

Answer 13

Similar to acute pain occurring later in the process

Continues to protect against damage

Question 14

Similar to acute pain occurring later in the process

Continues to protect against damage.

What kind of pain is this?

Answer 14

Subacute pain.

Question 15

What is chronic pain? What is it associated with? Does it have a role?

Answer 15

Persists beyond the normal time expected for healing of injured tissue

Associated with structural and functional changes in the central nervous system

No longer a symptom or protective

Question 16

Persists beyond the normal time expected for healing of injured tissue

Associated with structural and functional changes in the central nervous system

No longer a symptom or protective.

What kind if pain is this?

Answer 16

Chronic

Question 17

Give two kinds of stimulus or source of pain, and one example for each.

Answer 17

Chemical Sources

• Substances that are released with tissue injury (space occupying)

Mechanical Sources

• Normal Stress on Abnormal Tissue
• Ex: movement with a patient just out of a cast
• Abnormal Stress on Normal Tissue
• Not necessary for pathology to be present for pain to be produced

•Ex: bend finger back and hold it

Question 18

Fill out this graph:

Mechanical pain / Chemical pain

Frequency of pain

Effect of Altered Position or Movement

Quality of the Pain

Heat, Redness and/or Swelling

Effect of Rest

Irritability

Effect of Anti- Inflammatory Meds

Effect of Exercise or Manual Therapy

Answer 18

Mechanical pain / Chemical pain

Frequency of pain : intermittent / constant

Effect of altered position or movement: Pain increases or decreases with certain positions or movements / pain not altered by position or movement (worsens)

Quality of the pain : sudden, sharp twinges / pulsating, throbbing

Heat, redness and or swelling: None/ Common (signs of inflammation)

Effect of rest: Better after prolonged rest/ stiff and sore after prolonged rest

Irritability : Low to moderate / Moderate to high

Effect of anti-inflammatory meds: no effect (need for relief of the mechanism) Better

Effect of exercise or manual therapy: Effective / often not effective (thermal modalities)

Question 19

How can upregulation and sensitization happend?

Answer 19

• Nociceptive system is usually very quiet
• When injury activates the system, a relatively innocuous stimuli can trigger pain perception
• Events that were not painful before become painful

Question 20

What is nociceptice pain? What are its characteristics?

Answer 20

Nociceptive pain: normal pain response
• Usually aching or throbbing and well-localized, time limited (resolved once the tissue heals), responds well to analgesics

Question 21

What is neuropathic pain? What are its characteristics?

Answer 21

• Neuropathic pain: nerve damage (e.g., abnormal firing, increased signal to brain). It is a direct consequence of a lesion or disease affecting the somatosensory system
• Tingling, shock-like or burning pain, usually chronic and responds poorly to conventional analgesics

Question 22

What is hyperalgia?

Answer 22

Hyperalgesia: increased pain from a stimulus that normally provokes pain

Question 23

What is allodynia?

Answer 23

Allodynia: pain due to stimulus that does not normally provoke pain

Question 24

What could cause neuropathic pain? Explain and give examples.

Answer 24

May result from various causes that affect the brain, spinal cord and peripheral nerves, including:

• Complex Regional Pain Syndrome (II)

• Diabetic Neuropathy
• Phantom Limb Pain
• Post-Stroke

Often experienced in parts of the body that otherwise appear normal

Generally chronic, severe and resistant to over-the-counter analgesics

Question 25

What are the two areas usually found in neuropathic pain?

Answer 25

There is almost always an area that has a sensory deficit and within it is the area of maximum pain

Question 26

How could neuropathic pain be desribed by the patient?

Answer 26

Pain may be spontaneous or evoked (e.g., allodynia, hyperalgesia, hyperpathia) The quality of the pain is described as burning, electric shock, shooting and dysesthesia \*\*Often the stimulus/response relationship is unclear

Question 27

Name the three known mechanisms for neuropathic pain

Answer 27

Known mechanisms include: Ectopic impulse generation Response to activity in adjacent nerves Changes in sensitivity

Question 28

Describe the ectopic impulses theory

Answer 28

Stimulation independent Neuroma – high density of regenerated nerve endings Friction between nerves and rigid structures (e.g., musculoskeletal) Sustained compression

Question 29

Describe the "response to adjacent nerves" theory. What is the main mechanism called? What are the two ways that this mechanism can happend?

Answer 29

Ephatic-coupling * A mechanism in which neurons, that would otherwise operate in isolation, communicate via extracellular electrical signals * Within the same peripheral nerve Two ways: Physical Proximity • Action potentials traveling down a motor nerve can trigger impulses in a sensory nerve, where unmyelinated Chemical • Noradrenaline responsive fibres triggered by sympathetic activation

Question 30

What is enhanced mechanosensitivity? What are the two main types of sensitization?

Answer 30

Increased chemical concentrations are not necessarily enough to illicit activity, but do increase sensitivity Pressure or stretch may elicit an action potential (stimuli not typical for generating a response) Peripheral sensitization (or primary) – peripheral nerve endings Central sensitization (or secondary) - spinal cord and brain centers

Question 31

Describe peripheral sensitization. What are the three ways in which the increase could happend?

Answer 31

* Increased afferent nociceptor input to the CNS. Peripheral sensitization causes the amount of pain that you feel to be out of proportion to the extent of your injury * Increasing pain signals that could occur through: * Spontaneous firing, not requiring a signal• An easier threshold to reach * Increased firing frequency

Question 32

In peripheral sensitization, what is the role of the chemical mediators after a trauma?

Answer 32

Trauma Inflammatory Response Chemical Influence on Afferent Neuron Impulse

Question 33

What are the three pathways that peripheral sensitization could go through?

Answer 33

• Trauma triggers an inflammatory response – chemicals to affect afferent pathways Reduced response thresholds Recruitment of silent nociceptors Phenotype change

Question 34

Describe the reduced reponse threshold pathway of peripheral sensitization.

Answer 34

Chemicals released in response to tissue trauma will bind to ion channels in the membrane to alter permeability and excitability Indirect influence through 2nd messenger system (altered pH of the tissue) Inhibition of after-hyperpolarization

Question 35

Describe the recruit silent nociceptors pathway of peripheral sensitization.

Answer 35

* A large portion of Ad and C fibers are insensitive in normal, non-injured, non-inflamed tissues * No firing in ~ 1/3 of nociceptive specific neurons Injury releases inflammatory mediators to trigger their sensitivity to mechanical stimuli (mediators increase +ve, more and more +ve over time) Inability to turn off againàchronic pain (simulated tissue damage)

Question 36

Describe the phenotype change pathway of peripheral sensitization.

Answer 36

* Altered neuron type (nerve -\> pain fibre) * Non-nociceptive to nociceptive The actual type of afferent nerve can change cellular makeup to become a more painful source It occurs at the cellular levels Transcription changes occur within the cell Stimulation now interpreted as pain • Once was perceived as light touch/vibration

Question 37

What is central sensitization? What is it initiated by?

Answer 37

* An aspect of neuroplasticity (i.e., brain changes with experience) * Describes the changes at the cellular level which support neuroplastic changes in * Spinal cord * Supraspinal centres Your getting changes in your brain from the peripheral nociceptors Describes the changes at the cellular level… Spinal cord Supraspinal cord • Initiated by high activity levels the in peripheral nociceptors leading to activity- dependent increases in excitability of nerves in the spinal cord

Question 38

What are the two mechanisms of central sensitization called?

Answer 38

Chemical property changes Neuroanatomical reorganization

Question 39

Describe the chemical property changes pathway of central sensitization.

Answer 39

Chemicals release from nociceptive afferents induce changes in properties of spinal cord neurons Wide Dynamic Range (WDR) and NS neurons change firing patterns with non-noxious stimuli NS fire like WDR when central sensitization occurs Reduced threshold firing, increased rate of firing WDR: wide dynamic range- tends to be more sensitive because they respond to multiple signals - tends to fire faster NS: neuro specific neurons

Question 40

Describe the neuroanatomy reorganiszation pathway of central sensitization.

Answer 40

Reorganization of the cortical sensory map Sprout nerves to connect to pain pathways Changes their interpretation Continual stimulation of Ad and C fibres leads to Aβ fibre changes

Question 41

Why as clinicians should we be aware of sensitization?

Answer 41

BAD NEWS * The nervous system changes in response to pain * It becomes more sensitive to pain * What may be considered “excessive” pain behaviours may actually reflect sensitization of the nociceptive system GOOD NEWS • The nervous system changes in response to experience or intervention

Question 42

What is somatomotor dysfunction?

Answer 42

* Central nociceptive neurons synapse with other, non-nociceptive neurons * Upregulation (prolonged pain)àchanges in motor behaviour

Question 43

What is hyperalsthesia?

Answer 43

Hyperalsthesia = it is almost similar to hyperalgesia but it is stronger

Question 44

What are the three pathways of somatomotor dysfunction?

Answer 44

Enhance withdrawal reflex Vicious cycle model Pain adaptation model

Question 45

Two things can happen during enhanced withdrawal reflex. What are they called and how do they work?

Answer 45

RECIPROCAL INHIBITION Collateral branches of the afferent fibres synapse on inhibitory interneurons that suppress the activity of motor neurons innervating antagonist muscles CROSS EXTENSOR RESPONSE If the stimulated part is a limb, the response includes extension of the opposite limb (Muscle Stretch Reflex)

Question 46

Describe the vicious cycle model.

Answer 46

A simple model An abnormality in structure, posture, movement or stress results in pain that reflexively leads to muscle hyperactivity Increased sensitivity of muscle spindle afferents Increased muscle stiffness Increased muscle metabolite production • Spasm or fatigueàfurther pain, dysfunction

Question 47

What is the pain adaptation model?

Answer 47

• More complex – pain does not arise from the muscle itself

Question 48

As physiotherapists, it is important to note that a pain assessment does not mean we:

Answer 48

• Rely on changes in vital signs only * Decide that a patient does not “look in pain” * Know how much a procedure or disease “should hurt” * List types of pain descriptions assuming it will be one of them * Assume a sleeping patient does not have pain * Assume a patient will tell you when they are in pain

Question 49

What are the purposes of pain assessment?

Answer 49

* Diagnosis * Prognosis * Track changes over time (numeric rating scale) * Assist in clinical decision making – quality and type of pain to determine Rx

Question 50

What are some things you could be looking for during a pain history assessment?

Answer 50

Pain Characteristics – onset, duration, location, quality, intensity, associated symptoms, exacerbating and relieving factors [OPEN ENDED QUESTIONS!] Past and current management therapies Relevant medical and family history Psychosocial history Impact of pain on daily life – work, daily activities, personal relationships, sleep, appetite, emotional state Patient (and family’s) expected goals for treatment * ASK the patient about their pain (consider the ICF model) * Asking about ADL’s and IADL’s * Asking about physical activity, mood, sleep, appetite, energy level * Identify THE PATIENT’S preferred pain terminology * Hurting, aching, stabbing, discomfort, soreness * Use a pain scale that works for the individual * Insure understanding of its use * Modify sensory deficits

Question 51

What are three types of pain assessment?

Answer 51

* Self-report assessments * Behavioural assessments * Physiological/quantitative sensory assessments

Question 52

Give two examples of self-report pain • Visual Analog Scaleassessments.

Answer 52

* Visual Analog Scale * Questionnaires * E.g., McGill Pain Questionnaire (MPQ) * Select a word to describe pain * Each word has a separate score * Includes all dimensions of the pain experience

Question 53

How do you conduct behavioural pain assessments?

Answer 53

• Observation of painful behaviours * Bracing * Guarding * Facial grimacing * Exaggerate pain behaviours – inappropriate to use subjective ratings * Exaggerated in populations with poor communication (e.g., paediatrics, dementia)

Question 54

How do you conduct physiological/quantitative pain assessments (two ways)? Which procedure is more appropriate for which type of neuropathic pain?

Answer 54

Pressure (measure for hyperalgesia) • Apply pressure against the skin and increase pressure until the individual reports that it is painful Monofilaments (measure for allodynia) * Wires with increasing thickness that are pressed against the skin until wire bends * Greater wire thickness requires greater pressure to bend wire

Question 55

The use of drugs in clinical practice encompasses a wide variety of activities including:

Answer 55

* prescribing * compounding * dispensing * administering * advising * selling Restricted by physiotherapy provincial and federal legislation

Question 56

Use of drugs in clinical practice: there are a number of factors at play:

Answer 56

Access to information means patients are more informed and empowered to ask for additional information PTs are primary care providers, and as the first and sometimes only point of contact, PTs are being asked for advice related to OTCs OTCs do not require a prescription, so they are often seen as less risky and many PTs believe their education and experience is either adequate to provide advice or at a minimum, is better than nothing Consumers are expected to make decisions about their self care regarding OTCs and when they do, they assume personal responsibility When physiotherapy health care providers make a recommendation about OTCs, then greater weight gets put behind that advice HOWEVER! The wide margin of safety for OTCs does not preclude harm to patients or exemption from liability for physiotherapists should harm occur

Question 57

Meds and scope of practice: considerations:

Answer 57

Some jurisdictions prohibit administering, recommending and/or selling OTCs (BritishColumbia, Manitoba and Nova Scotia) If your jurisdiction does not prohibit administering, recommending, and/or selling OTCs, this does not mean you should do it just because you can - consider patient interests over your own interests If you do decide to administer, recommend and/or sell OTCs, consider your scope of practice, your personal competence, patient risk, professional liability and appropriateness – collaboration with other health professionals is recommended Always use judgement and apply reasoning - patient safety should be the primary focus