Plasticity of Pain pathways

Question 1

What makes pain complicated?

Answer 1

-multiple brain regions involved in experience of pain
-depends on emotional state/history of pain
-requires neuroanatomical and neurophysiological pathways

Question 2

What can a pre-existing injury do to pain?

Answer 2

Can lead to hypersensitivity of pain

Question 3

Pain hypersensitivity

Answer 3

a state in which more pain is experienced for a particular injury

Question 4

Types of pain hypersensitivity

Answer 4

1.Hyperalgesia

2. Allodynia

Question 5

Hyperalgesia

Answer 5

increased responsiveness to a noxious stimulus

ex. animal with injury, then hit again will result in increase in pain… tries to help with healing

Question 6

Allodynia

Answer 6

Pain experienced in response to a normally non-noxious stimulus

ex. human with spinal cord injury often feel pain during simple touch

Question 7

2 conditions leading to pain hypersensitivity

Answer 7

1.Tissue inflammation= inflammatory pain

2.Damage to the nervous system (PNS or CNS)= neuropathic pain

Question 8

Inflammatory pain

Answer 8

local disruption of tissues= hemorrhage, inflammation, increase in inflammatory mediators and bruising/swelling.
>leads to increase in receptor sensitivity and therefore pain!

Question 9

Neuropathic pain

Answer 9

Severe damage that causes the axons or nerves to be severed. This can lead to inappropriate sprouting or increase in neural connections.

> Leads to increase or abnormal input into CNS and increase pain

Question 10

2 mechanisms of neural plasticity leading to inflammatory pain

Answer 10

1.Peripheral sensitization- increased excitability of nociceptors when exposed to inflammatory mediators
>due to lower threshold activation of ion channel receptors= increased frequency of nociceptors firing

2. Central sensitization- increased excitability of spinal pain relay neurons from sustained firing of nociceptors (from peripheral sensitization) resulting in lower firing threshold

Question 11

Windup of central sensitization

Answer 11

Central sensitization takes longer to occur. Needs a “windup” for the lower threshold of the pain relay neurons to occur

Ex. animal with broken leg immediately vs. 7 days later

Question 12

Plasticity of inflammatory pain

Answer 12

-Over time, will decreased. Only present when inflammatory mediators present

-pain hypersensitivity is protective to allow time to heal

Question 13

What causes neuropathic pain?

Answer 13

-occurs due to damage to nervous system

-Maladaptive response: NS tries to repair injuries through excess branches or branches in the wrong spot which can lead to increased pain.

Question 14

Neuropathic pain characteristics

Answer 14

-uncommon
-not temporary= long lasting or permanent= “learned pain”

Question 15

Balanced multimodal analgesia

Answer 15

**important to target different areas of the body to relieve pain… because everything is interconnected

Need to inhibit perception (opioids), transmission (local anesthetics), transduction (NSAIDs), and modulation of spinal pathway (alpha 2 agonists)