1. Pain Pathways

Question 1

What is pain?

Answer 1

an unpleasant sensory and emotional experience that is associated with or resembles actual or potential tissue damage

Question 2

Pain is a net effect of a complex interaction of the ascending and descending NS’s involving:

Answer 2

biochemical, physiologic, psychological, and neocortical processes

Question 3

Pain classified by:

Answer 3

Duration
- acute or chronic
Cause
- cancer related
Mechanism
- nocioceptive (physiological)
- neuropathic (pathological)

Question 4

Caused by noxious stimulation due to injury, disease process, or abnormal function of muscle or viscera
- somatic
- visceral

Answer 4

Acute Pain

Question 5

Superficial: skin, SubQ
- cuts, burns

Deep: muscles/bone
- fracture, arthritis

Answer 5

Somatic Acute

Question 6

From organs
- angina, UTI, peptic ulcer

Referred pain
- pain perceived at site different from it’s point of origin, innervated by the same spinal segment
- ex: MI pain in L arm, neck, chest

Answer 6

Visceral Acute

Question 7

Acute vs. Chronic

Answer 7

A: sudden, short. resolves with healing
C: insidious onset, persists

A: warning of actual damage
C: false alarm

A: severity correlates with amount of damage
C: not

A: CNS intact, pain is symptom
C: CNS dysfunctional, c=disease

A: less psychological (anxiety or sleeplessness) goes away
C: depression, anger, fear, social withdrawl

Question 8

extends 3-6 months beyond onset or beyond expected healing period

Answer 8

Chronic Pain

Question 9

may be nocioceptive, inflammatory, neuropathic, or functional

Answer 9

Chronic pain origins

Question 11

psychological mechanisms or environmental factors play a major role

Answer 11

Distinguishing factor of Chronic pain

Question 12

Pain that occurs in response to tissue damage/injury

Can be well localized when it comes from soft tissue; less localized coming from viscera

Answer 12

Nocioceptive Pain

Question 13

Pain caused by lesion or disease of the PNS or CNS

Nerve damage/persistent stimulation results in rewiring of pain circuits

Causes spontaneous nerve stimulation, autonomic neuronal stimulation, increased discharge of dorsal horn neurons

Answer 13

Neuropathic Pain

Question 14

nocioceptive and neuropathis pain are not…

Answer 14

mutually exclusive (can have both together)

Question 15

Nocioceptive (No) vs Neuropathic (Ne)

Answer 15

No - well localized
Ne - not

No - sharp, worse with mvmt
Ne - burning, shooting, numb, pins and needles

No - obvious injury / disease
Ne - not obvious

No - inflammation
Ne - nerve injury, wiring change, abnormal firing, loss of modulation

No - physiological
Ne - pathological

Question 16

free sensory nerve ending present in most tissues of the body

Answer 16

Nocioceptors

Question 18

acids or compounds produced in the body

ex: bradykinin, histamine, prostaglandin

Answer 18

Chemical Nocioceptors

Question 19

Pressure

Answer 19

Mechanical / Physical Nocioceptors

Question 20

the level of stimulation to activate the nerve ending sufficiently for the individual to perceive pain

Answer 20

Pain Threshold

Question 21

the ability to withstand pain or the perception of its intensity
(psychological, state of mind affects perception)

Answer 21

Pain Tolerance

Question 22

neuron that receive impulse from the skin and proprioceptors and send it to the spinal cord

Answer 22

First-order Neuron (DRG)

Question 23

located in dorsal horn, 1st odred synapse with these neurons to send impulse up the SC to the thalamus and cerebellum

Answer 23

Second-order Neuron

Question 24

pick up neural impulse from the thalamus and carry it on to the somatosensory portion of the cerebral cortex

Answer 24

Third-order Neuron

Question 25

where modulation of pain-related info first occurs

Answer 25

Superficial Lamina I + Substansia Gelatinosa

Question 26

grey matter structure, responsible for relaying pain, temperature, and light touch sensation to the brain -major synaptic site btwn 1 and 2 order neurons, with lots of interneurons to modulate communication. - high concentration of substance P (causes pain), enkephalins, endorphins, dynorphins, and corresponding receptors

Answer 26

Substansia Gelatinosa

Question 27

transmit impulses rapidly

Answer 27

Myelinated A delta fibers

Question 29

transmit impulses slowly

Answer 29

Unmyelinated C fibers

Question 30

Acute pain is transmitted by...

Answer 30

A delta fibers sharp, sudden, localized pain related to thermal and physical stimuli primarily from skin and mucous membranes

Question 31

Chronic pain is transmitted by...

Answer 31

C fibers Receive thermal, physical, and chemical stimuli from muscle, tendons, the myocardium, and the digestive tract. also from skin. Often diffuse, burning, or aching

Question 32

used to test for areas of sensory loss or pain sensation and thus determine the site of damage after spinal cord injuries

Answer 32

Dermatomes

Question 33

reflex at ________ responds to pain signal

Answer 33

Spinal cord Results in motor (efferent) impulse back to muscle Initiates involuntary muscle contraction to move body away from pain source

Question 34

Spinothalamic Bundle (ascending pathways)

Answer 34

neospinothalamic tract + paleospinothalamic tract Double pathway explains the 2 stages of pain often experienced with injury to the skin (sharp then dull) Spinothalamic tracts connect with reticular formation in the brain, hypothalamus, thalamus and other structures Ascends to the somatosensory area of the parietal lobe in cerebral cortex

Question 35

Descending Pathways

Answer 35

Descending pain modulatory system is triggered once pain signal has reached cortex GOAL: modulate pain signal through neuronal inhibition to allow an organism to function enough to respond to pain source (top down) PAG receives pain info via spinomesenphalic tract relays it to the rostral ventral medulla where signal sent down spinal cord This activates the endogenous opiate system to suppress pain

Question 36

areas of the brain that play a role in pain relay and perception

Answer 36

RAS Hypothalamus Thalamus PAG RVM

Question 37

influence brain's awareness of incoming pain stimuli - drugs can depress RAS and decrease pain perception/experience

Answer 37

Reticular Activating System (RAS)

Question 38

impacts pain response through connection with pituitary glands and SNS

Answer 38

Hypothalamus

Question 39

serves as a relay center and processes nociceptive info before transmitting it to various parts of the cortex

Answer 39

Thalamus

Question 40

midbrain structure plays key role in pain modulation; inhibits and facilitate pain perception with connections to the thalamus, RVM, and dorsal horn

Answer 40

Periaqueductal Gray (PAG)

Question 41

brainstem structure made up of the nucleus raphe magnus, the nucleus gigantocellularis pars alpha (GiA), and the adjacent reticular formation. t modifies ascending signal reaching the brain as well as modulating descending signals.

Answer 41

Rostral Vental Medulla (RVM)

Question 42

The _______ pathway is one of the best-studied circuits in the descending pain modulation system. Its activation facilitates and inhibits pain.

Answer 42

PAG-RVM

Question 43

3 types of opioids and opioid receptors to regulate neurotransmission of pain signals

Answer 43

B-endorphins - which predominantly binds to mu opioid receptors Dynorphins - which predominantly binds to kappa opioid receptors Enkephalins - which predominantly binds to delta opioid receptors

Question 44

Opioid receptor activation leads to

Answer 44

A reduction in NT release and cell hyperpolarization, reducing cell excitability.

Question 45

Opioids can regulate pain on several levels within the:

Answer 45

Spinal Cord Brainstem Cortex

Question 46

Opioid receptors located in:

Answer 46

Brain: thalamus, PAG, RVM SC: dorsal horn Peripheral Organs: analgesic effects mediated via mu receptors

Question 47

Opioid receptors in dorsal horn

Answer 47

Post-synaptic ends of second-order neurons have opioid receptors within the membrane Pre-synaptic ends where first-order neurons contain opioid receptors

Question 48

Highest densities of opioid receptors in the brain

Answer 48

Thalamus Midbrain PAG RVM

Question 49

PT Implications

Answer 49

helps PTs explain that pt's amount of pain might not relate to damage level. - educate pts on descending pain modulatory system Anatomy knowledge of DPMS helps physiotherapists utilize management strategies to to access and activate system. - adding distractions manual techniques (mobs, manips) have been proposed to activates system + contribute to therapeutic effects