Neuropathic Pain Flashcards
Define: pain
an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or describe in terms of such damage
What are the 2 versions of pain?
Chronic (long term)
Acute (short term)
Is there treatment for chronic pain?
NO. you can only reduce the pain to a tolerable level that will not interfere with their daily function
What are the two main types of pain?
Nociceptive - pain associated with trauma, injury and inflammation (what we all think pain is)
Neuropathic - chronic pain syndrome that is associated with sensory abnormalities like numbness, tingling OR for example it may feel like you have a glove on (hand is warmer than the body)
Describe the pain processing loop in very basic terms.
Primary afferent (comes into the body) and carries pain impulse to the spinal cord, which relays info to brain. The brain then releases anti-pain sensing back to the spinal cord and then again to the site of injury.
What can chronic pain be caused by?
drug, disease, or injury that induces damage to the sensory fibres involved in the pain processing loop
What are some triggers of neuropathic pain?
- alcoholism
- amputation
- diabetes
- drugs
- herpes zoster
- HIV/AIDS
- MS
- spinal injury
- stroke
- tumor
What nerve fibres are associated with pain and temperature? Describe them as well please.
Aδ - small, myelinated
C - small, unmyelinated
*these are peripheral afferent fibres
What are the nerve fibres associated with touch and vibration?b Describe them as well please.
Aβ - large, myelinated
*Aβ in chronic pain start shooting chronic collaterals off of main root. Some of these hit the laminae 2 which means they are signalling the brain that the patient is in pain again.
Afferent = ?
coming into the spinal cord (dorsal)
Efferent = ?
leaving spinal cord (ventral)
Where are cortical neurons? When are they excitable?
In the brain.
In epilepsy.
Where are dorsal horn neurons? When are they excitable?
In spinal cord.
In neuropathic pain.
What is resting membrane potential of a cell?
-70 mV
Bc the cell membrane is actually more permeable to K+, the Ek is actually closer to -90 mV. How is this corrected back to the actual -70 mV?
Na-K pump
3 Na+ out
2 K+ in
At rest, what ion(s) are high intracellular ?
K+
At rest, what ion(s) are high extracellular ?
Ca2+, Na+ and Cl-
When the cell becomes more _____, that is what causes pain.
positive!
- whatever happens to make the cell more POSITIVE is what causes the pain response.
- whatever we can do to make the cell more NEGATIVE with stop the pain response.
So if we blocked Ca and Na channels, what would happen?
stop pain! :)
So if we blocked Cl channels, what would happen?
Pain would still be present :(
What would happen if we increased the flow of potassium (remember it flows from inside to outside of the cell)
stop pain! :)
What type of neurotransmitters bind to receptors and cause opening of Na and Ca channels?
Substance P
CGRP
How do anti-epileptic drugs work?
Block Ca and Na channels - therefore surpress pain
Describe the natural flow of ions.
K+ flows out.
Na+, Ca2+, Cl- flow in.
