Chapter Two - Pain and Management Flashcards
There are 3rd order neurons to several areas of the brain. What are their roles?
- Planning
- Sensory discrimination
- Memory
- Emotion
Describe the Gate Control Theory.
Possible brain modulation, not just a passive system• Includes descending pathways
What are endorphins?
Endogenous opioids released within the brain and spinal cord
What is the Neuromatric Theory?
Varied dimensions that overlap to create a unique experience
What are the four components of pain?
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
What is referred pain? Why do we have it?
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)
What is the difference between segmental and extrasegmental referred pain?
SEGMENTAL: pain referred to a structure within the same dermatome
EXTRASEGMENTAL: pain referred to >1 dermatome (multiple levelsàsevere)
In one sentence, what is a dermatome?
An area of skin in which sensory nerves derive from a single spinal nerve root
Where does the dermatome project? Where can pain refer alon a dermatome? In what direction, usually?
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
What is root pain? Is all root pain referred? Is all referred pain root pain?
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
What is acute pain? Give examples. What is its role?
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
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?
Acute pain
What is subacute pain? What is its purpose?
Similar to acute pain occurring later in the process
Continues to protect against damage
Similar to acute pain occurring later in the process
Continues to protect against damage.
What kind of pain is this?
Subacute pain.
What is chronic pain? What is it associated with? Does it have a role?
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
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?
Chronic
Give two kinds of stimulus or source of pain, and one example for each.
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
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
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)
How can upregulation and sensitization happend?
- 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
What is nociceptice pain? What are its characteristics?
Nociceptive pain: normal pain response
• Usually aching or throbbing and well-localized, time limited (resolved once the tissue heals), responds well to analgesics
What is neuropathic pain? What are its characteristics?
- 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
What is hyperalgia?
Hyperalgesia: increased pain from a stimulus that normally provokes pain
What is allodynia?
Allodynia: pain due to stimulus that does not normally provoke pain
What could cause neuropathic pain? Explain and give examples.
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
What are the two areas usually found in neuropathic pain?
There is almost always an area that has a sensory deficit and within it is the area of maximum pain
How could neuropathic pain be desribed by the patient?
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
Name the three known mechanisms for neuropathic pain
Known mechanisms include:
Ectopic impulse generation
Response to activity in adjacent nerves
Changes in sensitivity
Describe the ectopic impulses theory
Stimulation independent
Neuroma – high density of regenerated nerve endings
Friction between nerves and rigid structures (e.g., musculoskeletal)
Sustained compression
Describe the “response to adjacent nerves” theory. What is the main mechanism called? What are the two ways that this mechanism can happend?
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
What is enhanced mechanosensitivity? What are the two main types of sensitization?
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
Describe peripheral sensitization. What are the three ways in which the increase could happend?
- 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
In peripheral sensitization, what is the role of the chemical mediators after a trauma?
Trauma
Inflammatory Response
Chemical Influence on Afferent Neuron Impulse
What are the three pathways that peripheral sensitization could go through?
• Trauma triggers an inflammatory response – chemicals to affect afferent pathways
Reduced response thresholds
Recruitment of silent nociceptors
Phenotype change
Describe the reduced reponse threshold pathway of peripheral sensitization.
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
Describe the recruit silent nociceptors pathway of peripheral sensitization.
- 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)
Describe the phenotype change pathway of peripheral sensitization.
- 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
What is central sensitization? What is it initiated by?
- 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
What are the two mechanisms of central sensitization called?
Chemical property changes
Neuroanatomical reorganization
Describe the chemical property changes pathway of central sensitization.
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
Describe the neuroanatomy reorganiszation pathway of central sensitization.
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
Why as clinicians should we be aware of sensitization?
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
What is somatomotor dysfunction?
- Central nociceptive neurons synapse with other, non-nociceptive neurons
- Upregulation (prolonged pain)àchanges in motor behaviour
What is hyperalsthesia?
Hyperalsthesia = it is almost similar to hyperalgesia but it is stronger
What are the three pathways of somatomotor dysfunction?
Enhance withdrawal reflex
Vicious cycle model
Pain adaptation model
Two things can happen during enhanced withdrawal reflex. What are they called and how do they work?
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)
Describe the vicious cycle model.
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
What is the pain adaptation model?
• More complex – pain does not arise from the muscle itself
As physiotherapists, it is important to note that a pain assessment does not mean we:
• 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
What are the purposes of pain assessment?
- Diagnosis
- Prognosis
- Track changes over time (numeric rating scale)
- Assist in clinical decision making – quality and type of pain to determine Rx
What are some things you could be looking for during a pain history assessment?
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
What are three types of pain assessment?
- Self-report assessments
- Behavioural assessments
- Physiological/quantitative sensory assessments
Give two examples of self-report pain • Visual Analog Scaleassessments.
- 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
How do you conduct behavioural pain assessments?
• 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)
How do you conduct physiological/quantitative pain assessments (two ways)? Which procedure is more appropriate for which type of neuropathic pain?
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
The use of drugs in clinical practice encompasses a wide variety of activities including:
- prescribing
- compounding
- dispensing
- administering
- advising
- selling
Restricted by physiotherapy provincial and federal legislation
Use of drugs in clinical practice: there are a number of factors at play:
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
Meds and scope of practice: considerations:
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
