Test 4: Multimodal Basic Overview

Question 1

What is the definition of pain?

Answer 1

An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.
-A physiologic, emotional, and behavioral experience.

Question 2

What is Algesia?

Answer 2

Increased sensitivity to pain.

Question 3

What is Algogenic?

Answer 3

Pain producing

Question 4

What is Allodynia?

Answer 4

A normally non-harmful stimulus is perceived as pain.

Question 5

What is Analgesia?

Answer 5

The absence of pain in the presence of normally painful stimuli.

Question 6

What is dysesthesia?

Answer 6

An unpleasant painful abnormal sensation whether evoked or spontaneous.

Question 7

What is hyperalgesia?

Answer 7

A heightened response to a normally painful stimulus.

Question 8

What is Neuralgia?

Answer 8

Pain in the distribution of a peripheral nerve/nerves

Question 9

What is Neuropathy?

Answer 9

An abnormal disturbance in the function of a nerve/nerves

Question 10

What is Paresthesia?

Answer 10

An abnormal sensation, whether spontaneous or evoked.

Question 11

What is acute pain?

Answer 11

-Pain caused by noxious stimuli
-Can be due to Trauma: Chemical, thermal, or mechanical
-Self limited: 1-14 days
-Intensity diminishes over time
-Should not last beyond the point of injury itself
-Affected by social, cultural, and personality factors
-Responds to pharmacotherapy: treat precipitating cause
Lasts less than 3 months

Question 12

What is chronic pain?

Answer 12

-Pain lasting longer than 3 months or beyond the course of healing. Can be due to poorly controlled acute pain.
-Can be malignant (r/t cancer or cancer treatment)
-Can be non-malignant (neuropathic, inflammatory, musculoskeletal, idiopathic, etc).
-Associated with insomnia, lost work days, impaired mobility, and emotional stress.

Question 13

What is Nociceptive Pain?

Answer 13

Pain identified with specific nociceptors.
-Somatic or Visceral

Question 14

What is a Nociceptor?

Answer 14

A receptor of a sensory neuron (nerve cell) that responds to potentially damaging stimuli by sending signals to the spinal cord and brain.

Question 15

What is Somatic pain?

Answer 15

-Pain with an identifiable locus as a result of tissue damage
-Tissue damage causes the release of chemicals from injured cells that mediate pain.
-Well localized
-Sharp in nature: hurts at the point or area of stimulus.

Question 16

What is Visceral pain?

Answer 16

-Associated with the distention of an organ capsule or the obstruction of a hollow organ.
-Accompanied with autonomic reflexes such as N/V/D
-Diffuse pain, can be referred.
-Dull, cramping, squeezing, or vague pain.

Question 17

What is Non-Nociceptive pain?

Answer 17

-Neuropathic pain
-Due to damage to the CNS or PNS nerves.
-Results in abnormal processing of painful stimuli.
-Dysfunction of the CNS that allows for spontaneous excitation in chronic pain states.
-Described as burning, tingling, or shocklike.
-Can treat with different modalities, such as corticosteroids, ketamine, anti-convulsants, anti-depressants, lidocaine, or cannabinoids.

Question 18

What is Idiopathic (Psychogenic) pain?

Answer 18

-A type of non-nociceptive pain
-Associated with chronic pain states
-Pain with no apparent cause
-Psychological symptoms

Question 19

What is Substance P?

Answer 19

-A peptide found and released from the peripheral afferent (sensory) nociceptor C fibers
-Algogenic: Pain producing.
-Involved with slow, chronic pain
-Acts via the G-protein linked neurokinin-1 receptor resulting in vasodilation, extravasation of plasma proteins, degranulation of mast cells, and sensitization of the stimulated sensory nerve

Question 20

What is Glutamate?

Answer 20

-A major excitatory neurotransmitter released in the CNS and from the Aδ & C primary afferent nerve fibers
-Effects are instantaneous, producing initial, fast, sharp pain

Question 21

What are Bradykinins?

Answer 21

-Released by tissue damage
-A peptide released during the inflammation process and is algesic (causing pain)
-Direct stimulating effect on peripheral nociceptors via specific bradykinin receptors (B1 & B2)

Question 22

What is Histamine?

Answer 22

-An amine released from mast cell granules, basophils, and platelets via Substance P
-Reacts with various histamine receptors to produce edema and vasodilation

Question 23

What is Serotonin?

Answer 23

-An amine stored and released from platelets after tissue injury
-Reacts with multiple receptor subtypes and exhibits algesic effects on peripheral nociceptors
-Can potentiate bradykinin induced pain

Question 24

What are Prostaglandins?

Answer 24

-A metabolite of arachidonic acid (along with thromboxane and leukotrienes)
-Synthesized from COX-1 and COX-2
-Associated with chronic pain
-Sensitize peripheral nociceptors causing hyperalgesia

Question 25

What are Cytokines?

Answer 25

-Released in response to tissue injury by a variety of immune and non-immune cells via the inflammatory response
-Include interleukin-1β, interleukin-6, and tumor necrosis factor-α
-Can lead to the increased production of PG’s, inciting and sensitizing nociceptive fibers

Question 26

What is Transduction?

Answer 26

The transformation of a noxious stimuli (chemical, mechanical, or thermal) into an action potential.

Question 27

What is Transmission?

Answer 27

The process by which an AP is conducted from the periphery to the CNS.
-Occurs via 2nd and 3rd order neurons that carry message to the contralateral side.
-Enters via the dorsal horn (Ascending pathway), and moves to contralateral side.
-Involves substantia gelatinosa.
-3rd order neurons take the info to the somatosensory cortex where perception can occur.

Question 28

What is Perception?

Answer 28

Occurs once the signal is recognized by various areas of the brain

Question 29

What is Modulation?

Answer 29

The brain’s response to the AP, alteration of neural afferent activity along the pain pathway.
-Suppresses or enhances pain signals
-Can activate our own analgesic system
-Motor response to remove noxious stimuli.

Question 30

Describe the process of Transduction.

Answer 30

1) Noxious stimuli is detected by nociceptors (free nerve endings).
-Noxious stimuli is conducted to the dorsal horn of the spinal cord via A delta fibers or C fibers
2) Biochemical events:
-Release of chemical mediators from the inflammatory response (ex: Bradykinins)
-Release of neurotransmitters from the nociceptive nerve endings
3) Stimulation of peripheral nociceptors:
-Depolarization: Influx of Na
-Repolarization: Efflux of K
4) Action potential results and pain impulse is generated.

Question 31

What are A Delta Fibers?

Answer 31

-Large, myelinated fibers.
-Primary afferent neurons of fast, sharp pain
-Conduct AP’s at velocities between 6-30m/sec – first pain
-Responsible for reflex withdrawal mechanism

Question 32

What are C Fibers?

Answer 32

Smaller, non-myelinated fibers
-Conduct AP’s at velocities between 0.5-2m/sec – second pain
-Delayed, slow conduction – dull, burning, throbbing, and aching

Question 33

Describe the process of Transmission.

Answer 33

Occurs via the Spinothalamic (Anterolateral) System.
1) Primary afferent neurons (Aδ & C fibers) have cell bodies located in the dorsal root ganglia (!) of the spinal cord.
-Upon entering the dorsal cord, these fibers segregate and ascend or descend several spinal segments in the tract of Lissauer.
-After leaving the tract of Lissauer, the axons of the primary afferents enter the gray matter of the dorsal horn, where they synapse with second-order neurons and terminate primarily in Rexed laminae I, II, and V.

2) Second order Neurons: two types exist (Nociceptive neurons or Wide-Dynamic range (WDR) neurons)
-Initiated/Generated in Rex Laminae I, II & V (layers of gray matter in the spinal cord)
-Cross the midline of the spinal cord through the anterior commissure
-Ascend in the anterolateral pathway to the thalamus
-Synapse with Third-order neurons in the lateral thalamus

3) Third order Neurons:
-Reside in the lateral thalamus & intralaminar nuclei
-Send AP to the Cerebral Cortex

Question 34

What are Nociceptive Neurons (2nd order neurons)?

Answer 34

Nociceptive neurons receive input solely from primary afferent Aδ and C fibers.

Question 35

What are Wide Dynamic Range (WDR) Neurons (2nd order neurons)?

Answer 35

Wide Range (WDR) neurons receive input from both nociceptive (Aδ & C) fibers and non-nociceptive primary afferents (A & β) fibers
-Activated by both noxious and innocuous stimuli

Question 36

What are the areas of the brain involved in Perception?

Answer 36

Amygdala
Somatosensory areas of the cortex
Hypothalamus
Anterior cingulate cortex

Question 37

Describe the process of Modulation.

Answer 37

Occurs via Descending Efferent Modulatory pathways (the body’s endogenous analgesia system/pain control system).

1) Descending axons from the cerebral cortex, hypothalamus, periaqueductal gray area (PAG), nucleus raphe magnus (NRM) and locus coeruleus (LC) via the Dorsolateral Funiculus (DLF) synapse with the brain & spinal cord dorsal horn to suppress pain transmission.
2) Action potentials arrive at the substantia gelatinosa via the DLF, and activate Enkephalin-releasing neurons.
3) Enkephalin then binds to the opiate receptors on presynaptic 1st order or post-synaptic 2nd order afferent fibers, which decreases Substance P release.
4) Decreased Substance P release = suppression of ascending pain transmission.

Question 38

What are the Inhibitory Neurons that are released during Modulation via the Descending pathway?

Answer 38

Several neurotransmitters and their receptors play critical roles in the inhibitory modulation of pain, including the inhibitory endogenous opioids (enkephalin/dynorphin).

Inhibitory neurotransmitters released via the descending pathway:
-Glycine
-GABA
-Enkephalin
-Serotonin
-Norepinephrine