Pain Pathophysiology Flashcards
Name the type of pain. Normal response to noxious stimulus, producing protective behavioral responses to potential or actual tissue damage
Physiologic pain
Name the type of pain. Sudden onset of pain, may be severe but disappears when stimulus is removed
Acute pain
Name the type of pain. Pain lasting several weeks to months and persists beyond the expected healing time.
Chronic pain
Name the type of pain. Originates from damage to bone, joint, muscle or skin.
Somatic pain
Name the type of pain. Originates form internal organs
Visceral pain
Name the type of pain. Originates from injury to the peripheral or central nervous system.
Neuropathic pain
Name the type of pain. Originates from tissue damage.
Inflammatory pain
Name the type of pain. Originates form one part of the body but perceived as occurring in another
Referred pain
What four things make up the pain pathway
Transduction
Transmission
Modulation
Perception
Describe the pain pathway.
Peripheral pain receptors activated by stimulus –> signal communicate through nerve fibers to the spinal cord –> nociceptive input modified at spinal cord –> conscious recognition of pain at cerebral cortex
What do mechanoreceptors respond to?
Stretching, compression and crushing
What do thermoreceptors respond to?
Heat/cold
What do chemoreceptors respond to?
Neurotransmitters, prostaglandins and autocoids (inflammatory proteins)
Which nerve fibers are myelinated and have fast transmission. Typically involved with acute, sharp and rapid onset pain.
A-d fibers
Which nerve fibers are nonmyelinated, slow transmission. Involved with chronic, dull and aching pain
C-fibers
Where do afferent peripheral nerves enter spinal cord?
Dorsal roots (grey matter) and ascend via spinothalamic and spinoreticular tracts to brain
What are two excitatory substances?
Substance P (NK1 receptor) and glutamate (NMDA)
What are examples of inhibitory substances?
GABA and endogenous opioids
What kind of pain is transmitted through the spinothalamic tract?
Superficial pain- terminates at the thalmus
What kind of pain is transmitted through the spinoreticular tract?
Deep and visceral pain
What is a systemic consequence of unmanaged pain?
Stress response (tachy, hypertension, increased cardiac workload, atelectasis, hyperventilation, hypoxia, nausea, ileus and urinary retention)
T/F: Pathologic pain is adaptive
FALSE
Pain evoked by stimulus not normally causing pain is known as what?
Allodynia
Increased/exaggerated response to stimulus that is normally painful is known as what?
Hyperalgesia
What is the difference of primary and secondary hyperalgesia?
Primary: at site of injury
Secondary: occurs in surrounding tissues
Describe peripheral sensitization
increase in activity, excitability, and responsiveness leading to primary hyperalgesia
Summation of painful stimulation in spinal cord-mediated by C-fibers and contributes to central sensitization
Windup pain
What is the mechanism of windup pain?
Removes Mg block on NMDA receptor allowing receptor to be available for glutamate binding and increase pain transmission
Increase in nerve excitability and responsiveness in the CNS leading to primary and secondary hyperalgesia and allodynia.
Central sensitization
T/F: Central sensitization increases dorsal horn excitability and decreased inhibition at spinal cord level (decreased GABA)
TRUE
What does central sensitization result in?
Hyperalgesia, allodynia, spontaneous pain and pain memory
What is a term for loss of sensitivity to pain?
Analgesia
What is the advantage of physiologic pain?
Prevents tissue damage
Which pain fiber would most likely involved in transmitting sharp, fast pain?
A-d fibers; C-fibers are responsible for slow chronic pain
What kind of pain would be created by a broken bone, brachial plexus avulsion, gastric dilation and hip dysplasia?
Broken bone: somatic pain and inflammatory pain
Brachial plexus: neurological pain-acute
GDV: visceral acute pain
Hip dysplasia: chronic inflammation and somatic pain
What are the major excitatory and inhibitory neurotransmitters involved with pain transmission?
Glutamate and substance P are excitatory and GABA is inhibitory
What are the physiologic consequences of untreated/chronic pain
Stress response, immunosuppression, exhaustion, GI CV respiratory effects and HYPERglycemia
What strategies could be used to prevent peripheral sensitization? NSAIDs/topical anesthetic.
Central sensitization: ketamine and all other drugs acting on spinal cord
Does general anesthesia prevent either peripheral or central sensitization?
No, all of these things are happening, your patient is just unaware-which is why it is still important to give analgesics to your patients
