Pain Intro/Pathophysiology/Assessment Flashcards
What 3 components do you need to experience pain?
- Sensory component
- signals from periphery tissues - Emotional component
- pain is distressing - Cognitive component
- context of which you experience pain and the brain tries to signal you
T/F Pain is a stimulus
False
- it is an event and a perception
- need brain to feel pain experience
What drives the concept of multi-disciplinary treatment?
The Bio-Psycho-Social Model
- Physiological injury occurring in the context of an individual’s pre-existing psychological condition & experience
- In a specific SOCIAL setting (including personal & work related relationships)
Unfolding according to principles of behavioural learning
What is the most commonly experienced pain worldwide?
Acute pain
What are the barriers to pain management worldwide? (12)
- Low priority in most countries
- Different public health focus
- Lack of facilities
- Shortage of supplies
- Shortage of med schools
- Lack/absence of pain curriculum in med training
- Shortage of trained pain professionals
- Poverty
- Rural locations
- Absence of government commitment
- Patient factors (fear, privacy)
- Policy restrictions
Define pain according to IASP
An unpleasant SENSORY and EMOTIONAL experience associated with, or resembling that associated with, ACTUAL or POTENTIAL tissue damage.
What is painexhibit.com mission for patients
*This is an educational and visual arts exhibit from artists suffering with chronic pain who use their art for expressing some aspect of their pain experience
- Since pain is not visible on CT, x-ray, seen in blood work
Mission: Educate HCP and public about chronic pain through art, and to give voice to the many who suffer in abject silence.
What is the purpose of the single convention of narcotic drugs? (2)
- Limit possession, use, trade in, distribution, import/export, manufacture & production of drugs for exclusively medical & scientific purposes
- Assess drug trafficking through international cooperation to deter & discourage drug traffickers
What are the 3 components of the pain human rights declaration of Montreal
- Right of people to HAVE ACCESS
- Right of people to be ACKNOWLEDGED and INFORMED
- right to be treated by ADEQUATELY TRAINED HCPs
What are the components required for an effective national pain strategy? (4)
- Education for health professionals and population
- Timely access to pain care
- A quality improvement program to address access and standards of care
- Reasonable funding for research
What are the physiological consequences of pain (10)
- Decreased cognitive function, mental confusion
- Anxiety and depression
- Increased catecholamins, HR & BP, risk of MI
- Increased RR, sputum retention, infection
- Decreased gastric motility, urinary retention, fluid overload
- Hormonal changes
- Glucose intolerance, insulin resistance
- Muscle spasm, immobility
- Sexual dysfunction
- Peripheral and central sensitization (maladaptation)
Which hormones increase (4) and decrease (3) in relation to untreated pain?
Increase
- ADH
- Epinephrine
- Norepinephrine
- Cortisol
Decreased
- testosterone
- Aldosterone
- Insulin
How is pain different than other somatosensory modalities?
Pain has both a behavioural and emotional component
What is the purpose of pain
PREVENT TISSUE DAMAGE and the sensation must be strong enough to ALERT you & motivate you to take action
danger signal
What is congenital insensitivity to pain disorder?
Severe autosomal recessive condition in which a person CANNOT feel pain
- life expectancy reduced
What is adaptive vs maladaptive pain
Adaptive:
- Contributes to survival by protecting the organism from injury and/or promoting healing when injury has occurred
ex. touching something hot, chest pain for CHF
Maladaptive
- Expression of the pathologic operation of the nervous system: it is pain as a DISEASE
ex. neuropathic pain, fibromyalgia
Differentiate between acute pain and chronic pain
Purpose
Duration
Prognosis
Treatment goals
Acute
Purpose
- early warning
Duration
- < 3 months
Prognosis
- resolves with tissue healing
Treatment goals
- Pain relief, treat cause of pain
Chronic
Purpose
- no function
Duration
- 3-6+ months
Prognosis
- Persists long-term after acute injury
Treatment goals
- Pain reduction
What is Nociceptive pain? What is the process
NORMAL response to
- intense tissue-damaging
- potential tissue-damaging
- threatening stimuli
Process
1. Transduction
2. Transmission
3. Modulation
4. Perception
ex. stub toe
What is inflammatory pain?
Injury to somatic tissue leading to a chronic persistent release of chemical mediatory
- recruitment of “silent” neurons generate pain signals
ex. rheumatoid arthritis
What is neuropathic pain
Caused by a primary lesion, dysfunction, or damage in the CNS/nerves
= structural or functional maladaptive changes
Ex. spinal cord injury
- Central CNS lesion (post-stroke)
What is nociplastic or functional pain
No identifiable lesions or injury to CNS or PNS
- a malfunctioning nervous system
Eg. fibromyalgia, migraines, IBS
What is mixed type of pain
Combo of primary injury + secondary altered neuronal effects
eg. cancer pain
- bone pain (nociceptive) due to tumour damaging the bone
- Chemotherapy damaging nerve
What are clinical features of nociceptive pain in somatic and visceral
Somatic (skin, tissue, muscles, bones, joints):
* Superficial (occurs in skin & SC tissue) - SHARP, sometimes burning, well localized - superficial cuts, burns
* Deep (occurs in muscles, bones, joints, fascia, ligaments) - aching, THROBBING, dull, sore, well localized (more diffuse than superficial) - fractures, arthritis
Visceral (internal organs):
* Occurs in deep internal organs and cavities
* Pain comes from infiltration, distention, compression or stretching of organs
* Squeezing, aching, cramping, pressure, STRETCHING, distention poorly localized
* Can be associated with N/V/diaphoresis
Ex: Angina pectoris, peptic ulcer, intestinal or renal colic
What are clinical features of neuropathic pain
What are the 4 characteristics?
Described as:
NUMBNESS + TINGLING
Burning
ICY COLD - FROSTBITE LIKE
Paroxysmal
Lancinating, jabbing
Shooting, STABBING
Deep, dull, bonelike ache
Squeezing
Other descriptions:
- “Electrical” shock-like
- Skin feels “raw”
- “Broken-glass” feeling
Characteristics:
Allodynia: pain from a stimulus that does not normally evoke pain
Hyperalgesia: exaggerated response to a normally painful stimulus
Spontaneous pain: arises suddenly without any apparent peripheral stimulus, unpredictable and variable
Referred pain
What is the purpose of the nociceptor?
A type of noxious sensory neuron that distinguishes between noxious and non-noxius stimuli and transmit it to spinal cord
- usually dormant/silent
Thermal (heat, cold)
Chemical (tissue injury)
Mechanical (pressure)
T/F Nociceptors are primary sensory afferent neurons
True
What are the 4 characteristics of nociceptors?
- Free nerve endings
- NOT encapsulated, found at the interface between external and internal “worlds”. - Dependant on Ion channels and receptors at the peripheral terminal
- to help propagate electrical - .High threshold sensitivity
- Sensitive enough to detect potentially damaging stimuli but have a high threshold, allowing most activities to be pain-free. - Specialized response
- Allows for varying levels in sensation: e.g. prickling vs. burning
Differentiate between characterisitics of the 3 primary sensory afferents fibers: A-beta, A-Delta, C fibers
Threshold (low/medium/high)
Diameter (small/medium/large)
Myelination (yes/no)
Receptor (nociceptor/mechanoreceptor)
Pain order
A-beta
Threshold
- low (good)
Diameter
- large
Myelination
- yes
Receptor
- mechanoreceptor
Pain order
- does not respond to noxious stimuli
A Delta
Threshold
- medium
Diameter
- medium
Myelination
- Yes, thin
Receptor
- nociceptor
Pain order
- First pain
- Fast, sharp, stinging (think of paper cut)
C Fibers
Threshold
- high
Diameter
- small
Myelination
- NO
Receptor
- nociceptor
Pain order
- Second pain
- dull, aching, burning
T/F The nociception process occurs before cognitive process of pain
True
What occurs in the transduction step
Nerve endings on nociceptors (at the peripheral nociceptor terminals) participate in converting harmful/noxious stimuli into nociceptive electrical impulses (Action Potentials)
Which transducer ion channels are located on the peripheral terminals of the nociceptors (4)
TRPV1/TRPV2
- painful heat
DEG
- mechanical stimuli
ASICS
- Acid-sensing ion channels
- pH changes
P2X3R
- open when ATP escapes,
How is action potential created?
Step 1.3: Creating an inward depolarizing current (inside of membrane is more positive): Na+ and Ca2+ ions flow into peripheral terminals of the nociceptor
Step 1.4: Membrane depolarization: Na+ channels open fully (if stimulus is strong and lasts long) =
Step 1.5: Generation of an action potential (electrical signal)
Step 1.6: AP travels along sensory neuron axon –> axon’s central terminal in dorsal horn of spinal cord
What is the transmission step
Primary afferent neurons help transmit impulse to DORSAL HORN (relay or train station)
- Nociceptive pain fibers make synaptic connections in the laminae (layers) of the dorsal horn
- Glutamate and substance P are released to lower pain threshold
- Descending inhibitory pathways (i.e. using pain meds) can regulate the transmission of pain signals at the dorsal horn
What are the 3 tracts that you can go through in the anterolateral system
- Spinothalamic tract
- Spinoreticular tract
- Spinomesencephalic tract
What are the 2 tracts in spinothalamic tract
- Anterior segment
- transmit crude touch and pressure (no pain) - Lateral segment “discriminative pathway”
- transmits fast pain and temperature via A-delta fibers (first pain)
What does the spinoreticular tract transmit? “Affective pathway”
Transmit slow pain (C fibers)
- responsible for emotional pain
Secretes glutamate + Substance P
Cuts across to travel up to brainstem
What does the spinomesencephalic tract help with?
- Pain inhibitory descending tract
- Spinotectal tract helps with reflexes to painful stimuli (turns eyes toward pain source)
Spinohypothalamic triggers hormone response in response to pain
What is the perception step mean?
Evaluation of all incoming signals and incorporates memory and emotions into incoming signals
What is the modulation step? (dorsal horn)
Modulation is the process of either dampening (inhibiting) or amplifying pain signals.
- Occurs in the dorsal horn
Involves both descending and descending pathways (pain can be reduced before it reaches the brain)
What does the gate control theory state about pain modulation
Pain signals pass through a “gate” in the spinal cord (specifically, the dorsal horn)
- Signals from large fibers (like A-beta, for touch) can close the gate and reduce pain
- Signals from small fibers (like C fibers, for pain) open the gate and increase pain
If there is stronger activity from large nerve fibers there should be no pain and vice versa
- Example: When you rub your skin after bumping it, you’re activating large touch fibers → they close the gate → and reduce pain!
What are the 3 main areas in the descending pain inhibitory pathway (spinomesencephalic tract)
- PAG (periaquaductal grey region)
- Rape nuclei
- Locus coerulus
What is the PAG area in the spinomesencephalic pathway coordinate
- Coordinates body’s analgesic system
- Rich in opioid receptor and endogenous opioids (enkephalins, endorphins, dynorphins)
- Once this section is stimulated, it goes on to activate the raphe nuclei via enkephalins
What does the Raphe Nucelus area coordinate?
Once activated releases 5-HT (serotonin) to dorsal horn to release more enkephalins
- 5HT also DOWNREGULATES glutamate (pain causing NT) release by releasing GABA (pain inhibiting NT)
What does the locus corulus area coordinate
Synthesis of norepinephrine which helps in pain inhibition
What is the sensitization concept mean in chronic pain? 2 parts?
Increase in neuronal excitability making them more easily stimulated
Peripheral sensitization
Central Sensitization
Define peripheral sensitization
After tissue damage, the body releases things like ATP and prostaglandins.
- These chemicals activate pain-sensing nerves, making them respond more easily and more intensely than usual.
- If the inflammation continues, even fibers that don’t sense pain can start transmitting pain signals .
Over time, this leads to a state where even light or harmless touches feel painful (a condition called allodynia), and things that are normally painful feel much worse (hyperalgesia)
Define central Sensitization
Increased responsiveness of nociceptive neurons in the CNS to stimuli – everything feels like a noxious signal
Over time, even low-level signals release glutamate and Substance P, which keep the pain signals going. This creates a cycle where pain keeps feeding into itself, even if the original injury has healed.
Result RAPHE NUCLEI (Pain dampening area with 5-HT) becomes LESS effective
What is the importance of gilal cells
Not neurons, they make up over 70% of CNS cells and are essential for keeping neurons healthy and protected.
- When there’s injury, infection, or inflammation, glial cells get “activated” and start cleaning up toxic substances
CNS macrophages
What are 3 common challenges with pain assessment
- Healthcare systems
- lack of specialized care
- shorter visits - Patient beliefs
- cancer progression
- fear of addiction
- not wanting to disturb families - Age, culture, gender
- older generation think it is part of aging
- women feel more pain
Define total pain (7)
- Emotional
- Intellectual
- Physical
- Interpersonal
- Financial
- Bureaucratic
- Spiritual
What does OPQRSTUV stand for?
Onset
- Gradual or sudden?
Provoking factors
- what makes your pain better or worse?
Quality
- dull, aching, heavy, burning, hot icy, tingling
Radiation
- Referred pain
- Where does the pain travel?
Severity
- scale of 0-10
Temporal factors
- is 24/7? How long does it last
- AM/PM any pattern schedule?
Understanding the impact on patient
- How is affecting you? Loved ones?
Values of Patient
- Goals of treatment
- What would you like to be doing now that you are unable to due to pain?
In the Numeric rating scale What is considered mild
mod
severe
mild: 1-3
mod: 4-6
severe: 7-10
What are limitations of pain scores?
- Not a reflection of tissue damage or sensation intensity
- Cannot manage both baseline and spontaneous pain events
- Over time, pain is less linked with nociception and more with emotional and psychosocial factors
What was the strongest predictor of opioid/substance abuse?
If a patient has a diagnosis of non-opioid substance abuse (even alcohol)
Which factor was more prevalent in the opioid risk tool: Mental health disorders or non-opioid substance abuse?
Mental health disorders
What does the opioid risk tool assess? (5)
- Family history of substance abuse
- Personal history of substance abuse
- Age
- History of preadolescent sexual abuse
- Psychological disease
What is score considered low, mod, high risk of substance use? What does a high risk score mean
Low risk: 0-3
Moderate risk: 4-7
High risk: 8+
HIGH RISK DOES NOT MEAN A CONTRAINDICATION TO OPIOIDS - JUST BE CAUTIOUS.
What does the pediatric pain score look at? FLACC
Face
Legs
Activity
Cry
Consolability
What risk tool is used for critically ill & ventilated patients? What does it look at?
The behavioural pain scale
- Facial expression
- Upper limb movements
- Compliance with mechanical ventilation
