Pain & Mgmt Flashcards
Acute nociceptive pain w/ normal physiological activity in normal pain receptors can last up to ____
3 months (the time it normally takes for the tissue to heal)
Somatic pain
It is localized, and typically described as aching, stabbing, squeezing or throbbing
Visceral pain
Pain is localized or generalized and described as cramping, or gnawing.
It may be referred to the skin of the dermatome innervated by the same nerve as the viscus
All ____ fibers are unmyelinated.
sympathetic postganglionic
Describe Neuropathic pain
- Neuropathic Pain occurs when there is CNS +/or PNS dysfunction.
- Causes are numerous—nerve compression, ischemia, inflammation, infiltration, metabolic
- This pain is disproportionate to injury, & may outlast it
Peripheral C‐fibers: myelination?
• Unmyelinated (slow)
Peripheral A‐δ fibers: myelination?
Thinly myelinated (medium speed)
Peripheral C-fibers: type of pain?
Spontaneous, diffuse burning/aching
When primary afferents of pain pathway are activated, they release __a__ at synapses in dorsal horn (fast excitation).
They also release __b__ & __b__, which produce
a slower and longer-lasting excitation.
a) Glutamate
b) Substance P and Calcitonin gene-related peptide
The area to which visceral pain is referred corresponds to what?
The dermatome innervated by the spinal segment to which the visceral afferents project
Anatomic basis for referred pain?
The convergence of visceral and somatic pain fibers in a given dorsal root on the same pain-transmission neurons i.e. the neurons whose axons will cross the midline and form the spinothalamic tract.
The common explanation is the idea that spinal neurons are most often activated by inputs from the skin, so the brain “mislocalizes” activity evoked by input from deep structures to a place that roughly corresponds with the region of skin innervated by that segment.
What surgical procedure?
- the classic ablative surgery. Afterwards patients often report that the pain is just the same but now they don’t seem to care…
Cingulotomy
DBS for pain control would target what brain structure?
Periaqueductal gray stimulation
or
PAG plus somatosensory thalamus
If a painfully hot stimulus is applied to a normal subject, fMRI shows somewhat increased activity (blood flow) in the ___a___.
b. What happens if subject is asked to go to their “happy place” & not pay attention to painful stimuli?
a) Periaqueductal Gray
b) Blood flow in this area is increased
even more and the stimuli are reported to be
less unpleasant
What are the 2 effects of periaqueductal gray axons stimulating the serotonin-containing neurons of Raphe Nuclei?
The 5HT-containing neurons of Raphe Nuclei:
• Inhibit DRG pain axons directly (presynaptic)
• Inhibit neurons whose axons form the spinothalamic tract (either directly or via small interneurons in the substantia gelatinosa)
(descending pain control)
Functions of the serotonin cell bodies of the Raphe Nuclei?
Impulse control, Pain Modulation, Mood stability
- Help control arousal & aggression (in forebrain)
- Help modulate pain-related signals (in SC)
List some inputs to the Periaqueductal Gray Matter
- Hypothalamus
- Amygdala
- Many cortical areas include limbic and prefrontal cortex
- Spinothalamic tract axons (Input about level
of noxious stimulation)
Damage to the descending pain modulating circuits will affect the action of what type of drugs?
In animals, lesions in this pathway reduce the effect of opioid drugs given systemically
Neuropathic pain- cause & outcome?
Neuropathic pain is produced by direct damage to or dysfunction of peripheral or central pathways for pain (nerve compression, ischemia, inflammation, infiltration, metabolic)
Typically patients have loss or impairment of pain sensation AND spontaneous pain
What to include in taking the pain history of a patient?
PQRST
- P‐‐provocative/palliative measures, including treatments previously tried (what makes it better or worse?)
- Q—quality – patient’s own words. Their story is often more helpful than tests.
- R—region and radiation (where pain starts and moves to)
- S‐‐severity‐‐how bad is it at its worst, best and now? How does it affect their life? Analog scales
- T‐‐temporal course—acute, chronic or recurrent, look for history of trauma or new activity, how does it change during the day?
Assessment & Management of pain in a patient?
Identify anatomic structures that may be causing or worsening the pain‐‐correct underlying pathology if possible, or explain etiology
– Physical examination: Inspection (posture, pain behaviors) palpation (for masses, guarding), vitals, signs of sympathetic dysfunction (sweating, tachycardia, trophic skin changes)
Assess effect of pain on patient
– physical comfort , including sleep
– ability to carry out usual daily activities
– emotional toll on patient & family
Negotiate treatment strategy as appropriate.
– What meds or treatment are appropriate, acceptable to patient
– Psychosocial Hx important for prior substance abuse (drugs or alcohol) especially in chronic pain
Initial Drug Management for Pain ‐‐ how many pain meds to start off w/?
Optimize relief w/ 1 drug before changing or adding a 2nd drug.
Note: some drugs have ceiling effects
Also: avoid simultaneous use of multiple drugs from same class, especially multiple opioids.
When to use long acting medications in pain relief?
Use long acting medications when pain is chronic or constant.
Often ____ plus opioid reduces opioid dose needed to give good analgesia
COX inhibitor
If using opioids always give _____
stool softeners
If pain is neuropathic, addition of ______ in Tx may be needed
an antidepressant or anticonvulsant
How long does “chronic pain” last?
Chronic pain lasts longer than 3 months
i.e. it outlasts time for tissues to heal normally
T or F? Chronic pain alone is a disease state.
True. Chronic pain is a disease state in and of itself, & serves no physiologic role.
Most common type/location of pain?
Primary back pain
Describe the pain transmission pathway
Noxious stimuli activate sensory peripheral ending of afferent nociceptor by transduction –> message
What is the “Positive Pain Phenomena”?
Occurs when there is abnormal increased function of the sensory system.
Pain may be spontaneous or stimulus induced.
Spontaneous Positive Pain Phenomena?
– Paresthesia‐‐abnormal sensation. Usually described as tingling, prickling, or asleep.
– Dysesthesia‐‐severe, distressing paresthesia
Stimulus-induced Positive Pain Phenomena?
– Allodynia‐‐stimulus induces another type of sensation‐‐touch is painful, for example
– Hyperalgesia or hyperpathia‐‐painful stimulus causes more than expected perceived pain