Introduction to Pain Management Lecture 1 Flashcards
According to Cascade of Pain Classification:
How is “Longevity” classified?
Acute and Chronic
Define Pain (as by the International Association for the Study of Pain)
“An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage”
According to Cascade of Pain Classification, how long is pain endured to be considered “Acute”?
Acute is considered less than 3- 6 months
According to Cascade of Pain Classification, how long is pain endured to be considered “Chronic”?
Chronic is greater than 3- 6 months
According to Cascade of Pain Classification, how is the underlying pathophysiology classified as?
Nociceptive and Non-Nociceptive
Nociceptive pain is classified into what two categories?
Somatic and Viceral
*Associated with the stimulation of specific nociceptors and can be either somatic or viceral
Non-nociceptive pain is classified into what two categories?
Neuropathic and Idiopathic or Psychogenic
How is nociceptive, Somatic pain defined as?
Pain that has an identifiable locus as a result of tissue damage causing the release of chemicals from injured cells that mediate pain
What are the characteristics of nociceptive, Somatic pain?
What is an example of Somatic pain?
- Well localized (Type A nerve fibers)
- Sharp pain in nature
- Generally hurts at the point or area of stimulus
Example: A pin prick
How is nociceptive, Viceral pain defined as?
Diffuse and can be referred to another area of the body. It is often associated with distention of an organ capsule or the obstruction of a hollow viscus. Also, it is often accompanied with autonomic reflexes such as nausea, diarrhea, or vomitting
What are the characteristics of nociceptive, Viceral pain?
What is an example of Viceral pain?
- Dull
- Cramping
- Squeezing
- Often vague in nature
- Pressure pain that may radiate
Example: Generalized abdominal pain with nausea and vomitting for an appendicitis
How is non-nociceptive, Neuropathic pain defined as?
Caused by damage to peripheral or central neural structures resulting in abnormal processing of painful stimuli
What are the characteristics of non-nociceptive, Neuropathic pain?
What is an example of Neuropathic pain?
- Burning - Tingling
- Shock-like - Stabbing sensation
- Numbness - “Pins and Needles” sensation
- Throbbing sensation
Example: “Boot toe”
How is non-nociceptive, Idiopathic or Psychogenic pain defined as?
Associated with chronic pain states and is used to describe pain that has no apparent cause. Neither nociceptive or non-nociceptive mechanisms can be identified as the cause for pain, and psychological systems are commonly present
What is Algesia?
Increased sensitivity to pain
If it is “pain producing”, it is considered:
Algogenic
What is Allodynia?
Where a normally non-harmful stimulus is perceived as painful
The absence of pain in the presence of a normally painful stimulus is the definition of _________.
Analgesia
What is Dysesthesia?
An unpleasant painful abnormal sensation, whether evoked or spontaneous
A heightened response to a normally painful stimulus is considered to be ___________.
Hyperalgesia
What is Neuralgia?
Pain in the distribution of a peripheral nerve(s)
This is the abnormal disturbance in the function of a nerve(s)
Neuropathy
What is Parathesia?
An abnormal sensation, whether evoked or spontaneous
What are the FOUR processes that define Nociceptive Somatic Pain?
- Transduction
- Transmission
- Perception
- Modulation
In terms of Nociceptive Somatic Pain, what is Transduction?
Transformation of a noxious stimuli (chemical, mechanical, thermal) into an action potential
In terms of Nociceptive Somatic Pain, what is Transmission?
The process by which an action potential is conducted from the periphery to, but before, the CNS
In terms of Nociceptive Somatic Pain, what is Perception?
Occurs once the signal is recognized by several areas of the brain to include:
- The Amygdala
- Somatosensory area of the Cortex
- Hypothalmus
- The Anterior Cingulate Cortex
In terms of Nociceptive Somatic Pain, what is Modulation?
Involves altering neural afferent activity along the pain pathway; it can SUPPRESS or ENHANCE pain signals
What is another name for pain receptors?
Nociceptors, free nerve endings
Peripheral nociceptors that conduct stimuli to the _______ horn of the spinal cord, are categorized according to morphology. Morphology factors are: _________, __________, and ________.
- Dorsal
- Diameter
- Myelination
- Conduction velocity
What are TWO common nerve fibers associated with the transduction of peripheral nociceptors?
- Larger myelinated A- delta nerve fibers: Primary afferent neurons that conduct action potentials at velocities between 6 and 30 meters/second and elicit FAST SHARP PAIN
- Smaller unmyelinated C- nerve fibers: Conduct at velocities between 0.5 and 2 meters/second. AKA polymodal fibers because they respond to mechanical, chemical, and thermal injuries.
How are smaller unmyelinated C-fibers described as?
- Burning
- Aching
- Dull
- Throbbing
Describe how inflammation and peripheral nociception occurs
When peripheral tissues (skin, bone, viscera, etc.) receive chemical, mechanical, and/or thermal stimuli or are either traumatized by either surgery or injury; a series of BIOMECHANICS events take place in peripheral pain transduction
Name the chemical mediators and neurotransmitters
- Substance P - Serotonin
- Glutamate - Prostaglandins
- Bradykinin - Cytokines
- Histamine
Describe how chemical mediators and neurotransmitters work
They stimulate peripheral nociceptors, causing an INFLUX of SODIUM IONS to enter the NERVE FIBER membranes (DEPOLARIZATION) and a subsequent INFLUX of POTASSIUM IONS (REPOLARIZATION) resulting in an ACTION POTENTIAL generating a PAIN IMPULSE.
In which pathway does Transmission of nonciceptive pain occur?
Spinothalamic (anterolateral) Pathway
Where are the cell bodies of the primary afferent neurons (A-delta and C-fibers) located on the spinal cord?
The Dorsal Root Ganglia
Upon entering the ______ horn, these fibers _________ and descend or ascend several spinal segments in the _____________.
- Dorsal
- Segregate
- Tract of Lissauer
What happens after the pain impulse leaves the Tract of Lissauer?
The axons of the primary afferent enter the gray matter of the dorsal horn where they synapse with the second-order neurons and terminate primarily in the Laminae of Rexed.
At which laminae, in the Laminae of Rexed, do the primary afferent neurons terminate at?
I, II, and V
How many types of second-order neurons are there?
What are they?
Two types
- Nociceptive neurons: which receive input solely from primary A-delta nerve fibers and C-fibers
- Wide-Dynamic-Range (WDR) neurons: receive input from both nociceptive (A-delta and C-fibers) and non-nociceptive (A-beta) primary afferents
How are Wide-Dynamic-Range (WDR) neurons activated?
A variety of stimulants both innocuous and noxious
How do second-order neurons cross the the midline of the spinal cord?
Then what do they do?
Through the Anterior Commissure
They ascend through the anterolateral pathway of the spinothalamic tract up to the Thalamus.
Where do second-order neurons synapse with third-order neurons?
Then what do third-order neurons do?
Lateral Thalamus and the Intralaminar Nuclei
Send projections to the Cerebral Cortex
Once third-order neurons send projections (signals) to Cerebral Cortex what occurs?
Perception occurs once the signal is recognized by the different areas of the brain
Where does Modulation occur?
What can it do to pain?
Within the descending efferent pathways
It can either SUPPRESS or ENHANCE pain
What is considered the body’s “Pain Control System” or “Analgesia System”?
The Descending Efferent Modulating Pathway from the brain
Where do descending axons come from that synapse with and suppress pain transmission to the brainstem and the spinal cord dorsal horn?
Descending axons arise from:
- The Cerebral Cortex - Hypothalamus
- Thalamus - Periaquaductal Gray Matter
- Raphe Magnus Nucleus
- Locus Ceruleus (in the Pons) via the Dorsolateral Funiculis
What play an inhibitory role in suppressing pain during Modulation?
What are they?
Endogenous Opioids
- Endorphins
- Enkephalins
- Dynonorphins
What occurs with the presence of “Central Sensitization”?
Pain Modulation is enhanced
With pain-modulating neurotransmitters, what are the TWO excitatory neurotransmitters?
What receptors do they bind to?
Substance P and Glutamate
Substance P: Neurokinin 1 and 2 (NK1) (NK2)
Glutamate: NMDA, AMPA, and Kainate
With pain-modulating neurotransmitters, what are the FIVE inhibitory neurotransmitters?
What receptor do they bind to?
- Glycine: Chloride linked (GlyR)
- GABA: GABAa, GABAb, GABAc
- Enkephalins: Mu, Delta, Kappa
- Serotonin: 5-HT (5-HT1-3)
- Norepinephrine: Alpha 2 adrenergic
