Pain Modulation Flashcards
What is pain
An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage
What are the dualities of pain
Physiological experience and psychological experience
What are the goals of pain treatment (3)
- Resolve the underlying pathology causing pain
- Modify the patient’s perception of pain
- Allow the patient to maximize their functional abilities
What are the categories of pain (4)
- Nociceptive
- Neuropathic
- Psychogenic
- Carcinogenic
What is the function of pain (3)
- Warning for withdrawal
- Alerts that something is wrong
- Protective function
What are the 2 types of nociceptive pain
- Somatic
2. Visceral
What is somatic pain
Activation of nociceptors found in most body tissue
What is visceral pain
Activation of nociceptors found in viscera
Is visceral pain referred or localized
Referred
Is all of the viscera sensitive to pain
Nope
What are the types of neuropathic pain (2)
- Peripheral
2. Central
What is psychogenic pain
Pain that originates from nonorganic sources and is associated with emotional, cognitive, and behavioral responses
What are the 4 types of pain
- Acute
- Chronic
- Referred
- Radicular
What is carcinogenic pain
Pain caused by cancerous pathology that is severe
What is acute pain
Combination of unpleasant sensory, perceptual, and emotional experiences that occur in response to noxious stimulus
Characteristics of acute pain (3)
- Time limited
- Persists as long as noxious stimulus persists
- Serve a protective function
What is treatment of acute pain from musculoskeletal injury aimed to (3)
- Facilitate resolution of underlying problem
- Reduce inflammation
- Modify the transmission of pain from periphery to CNS
What is chronic pain
Continuous long term pain of more the 12 weeks after healing would have occurred
What causes chronic pain (2)
- Changes in sympathetic NS, adrenal activity, reduced production of endogenous opioids, or sensitization of primary afferents
- Increased sensitivity to noxious and non-noxious stimuli`
What is referred pain
Pain felt at a location distant from its source
What is radicular pain
Pain originating from an irritated nerve root that follows a dermatomal pattern
What are pain receptors called
Nociceptors
What are the 4 types of sensors
- Mechano
- Thermo
- Noci
- Proprio
What are the 2 categories of peripheral sensory receptors
Superficial and deep
What are the types of mechanoreceptors (4)
- Meissner’s corpuscles
- Pacinian corpuscles
- Merkle cells
- Ruffini endings
What are the 2 types of thermoreceptors
Cold and hot
What are the 3 types of proprioceptors
- GTO
- Pacinian corpuscles
- Ruffini endings
What do meissner’s corpuscles sense
Pressure and touch
What do pacinian corpuscles, merkle cells, and ruffini endings sense
Skin stretch and pressure
What do GTO sense
Change in muscle length and spindle tension
What do deep pacinian corpuscles sense
Change in joint position and vibration
What do ruffini endings sense
Joint end range and heat
Is the life of a sensor long or short
Short
Why is the life of a sensor short
The brain decides if we need more or less receptors to modulate sensitization of stimuli
True or False:
Nociceptors respond to all manners of stimuli
True
When does a nociceptor send a signal
When it is stimulated enough
What is the pain threshold
The number of receptors needed to fire
What are the 3 fibers in the peripheral nerve afferent fibers
- A beta fibers
- A delta fibers
- C fibers
What is the diameter, myelination and speed of A beta fibers
Diameter: 6-12 um
Myelinated
Speed: >30 m/sec
What is the diameter, myelination and speed of A delta fibers
Diameter: 1-6 um
Myelinated
Speed: 30 m/sec
What is the diameter, myelination and speed of C fibers
Diameter: 1mm
Nonmyelinated
Speed: 1-4 m/sec
What info do A beta fibers transmit (2)
Touch and vibration
What info do A delta fibers transmit (4)
Touch, temperature, pressure, and pain
What info do C fibers transmit (4)
Pain, touch, pressure, and temperature
Where do A beta fibers originate from
Hair follicles
Where do A delta fibers originate from
Warm/cold receptors, hair follicles, and free nerve endings
True or False:
A delta fibers are blocked by opiates
False
What percent of afferent danger transmitting fibers are C fibers
80%
What are group III afferent fibers
A delta fibers
What are group IV afferent fibers
C fibers
True or False:
C fibers are the largest amount of nociceptors we have
True
What type of fibers are activated by mechanical trauma
A delta and C fibers
What is the spinothalamic tract’s main function
Primary nociceptive pathway that transmits type/location of pain
What is the main function of the spinoreticular tract
Motivational, emotional, unpleasant aspect of pain
What is the main function of the spinomesencephalic tract
Sensorimotor integration of pain
What is the main function of the spinohypothalamic tract
Autonomic responses associated with pain
What are the 6 sub-cortical centers
- Reticular formation
- Periaqueductal gray
- Hypothalamus
- Pituitary
- Thalamus
- Limbic system
What is the main function of the reticular formation
Mediates motor, autonomic, and sensory functions
What is the main function of the periaqueductal gray
Directs descending inhibition
What is the main function of the hypothalamus
Controls endocrine functions and vegetative state
What is the main function of the Pituitary
Master gland for endocrine system
What is the main function of the thalamus
Final gateway and relay center
What is the main function of the limbic system
Involved in emotional, motivational, and affective behavior
What is the somatosensory cortex
Area of the brain that identifies location of pain and central processing center
What is the association cortex
Responsible for affect that is associated with danger signals and results in pain tolerance
Sensation of pain depends upon stimulation of specific nerve endings that are specialized for that sensation
Specific theory of pain
Sensation of pain results from appropriate intensity or frequency of stimulation of receptors that also respond to other stimuli like touch, pressure, and temperature
Pattern theory of pain
True or False:
In the pattern theory of pain there is CNS influence on pain perception
True
Desensitize peripheral receptors activated during the inflammatory process (change how receptors in the periphery are perceived)
Peripheral pain modulation
What facilitate nociceptor sensitivity
Bradykinin, prostaglandin E2, and serotonin
Nerve impulses evoked by injury are influenced in the spinal cord by other nerve cells that act like gates
Gate control theory of pain
Example of gate control theory
Hit funny bone and rub the area enough and it will eventually cause the pain to go away as long as you keep rubbing the spot once you stop it will come back
Uses feedback loops to inhibit pain transmission at dorsal horn which results in the release of endogenous opioids
Supraspinal and descending pain modulation theory
Separate opiate binding sites in the CNS and two peptides produced physiologic effects similar to morphine
Endogenous opioid system
How did they know they were opioids
They were blocked by naloxone which is an opioid antagonist
What are opiopeptins
They control pain by binding with specific opiate receptors in the nervous system
How do opiopeptins cause presynaptic inhibition
Suppress influx of calcium
How do opiopeptins cause postsynaptic inhibition
Activate outflow of potassium current
Low frequency, high intensity stimulation of the peripheral nerves used to enhance the production of endogenous endorphins in the anterior pituitary
Motor pain modulation
What is the end result of motor pain modulation
Stimulation of descending pain control system in dorsal horn
Stimulation of C fibers activates PAG region and second system activates the pons
Noxious pain modulation
What is the end result of the noxious pain modulation
Stimulation of descending inhibition system in dorsal horn
How long is pain blocked when using the noxious pain modulation
30 minutes to an hour
Pain is a multidimensional experience that is produced by characteristic patterns of nerve impulses that are determined by heredity
Neuromatrix theory
What is the neuromatrix theory dumbed down
Smile more have less pain
Application of medium frequency electrical current that hyperpolarizes membrane further and blocks APs
Nerve block pain modulation
How long does it take for adaption to begin
A few seconds
What is hyperalgesia
That which hurt now hurts more
What is allodynia
That which did not hurt now hurts
What is the semantic differential scales
Word lists and categories that represent various aspects of pain experiences and pt selects most appropriate words for their pain
What are non systemic analgesics
NSAIDs, acetaminophen, opiates, opioids, and antidepressants
What are the effects of NSAIDs (5)
- Analgesic
- Anti-inflammatory
- Anticoagulant
- Antipyretic
- Anticancer
How do NSAIDs inhibit pain
By inhibiting the conversion or arachidonic acid to cyclooxygenase and prostglandins
What are 5 NSAIDs
- Aspirin
- Ibuprofin
- Naproxen
- Piroxicam
- Celecoxib
What is acetaminophen
Tylenol
What is the big problem with acetaminophen
Liver damage
What are the adverse effects of opiates (8)
- Sedation
- Mood changes
- Confusion
- Respiratory depression
- Postural hypotension
- Constipation
- Nausea and vomiting
- Tolerance and dependence
how are spinal analgesics given
Epidural
What can be injected into the epidural
Opiates, local anesthetics, catabolic corticosteroids
What does heat do to nerve conduction
Increases it
What does cold do to nerve conduction
Decreases it
What are physical agents that stimulate large diameter afferent fibers (3)
- TENS
- Superficial massage
- Analgesic balms
What are physical agents that decrease pain fiber transmission (4)
- Cryotherapy
- Ultrasound
- Iontophoresis
- Phonophoresis
What are physical agents that stimulate small diameter afferent fibers and descending pain control mechanisms (2)
- Deep massage
2. TENS
What are physical agents that stimulate the release of beta-endrophins through prolonged small diamter fiber stimulation (2)
- TENS
2. E-stim
How long does it take for 5 minutes of cooling for decreased nerve conduction to be reversed
15 minutes
How long does it take for 20 minutes of cooling for decreased nerve conduction to be reversed
30 minutes
What are the advantages to physical agents (5)
- Fewer and generally less severe side effects than medications
- Patients do not develop physical dependency
- Do not cause sedation that would impair ability to work or drive
- Many are able to be applied independently
- May help remediate the underlying cause of the pain
What is a noxious stimulus
An actual tissue damaging potential
What is a non noxious stimulus
A stimulus that has limited to no potential for injury
