Chronic Pain Flashcards
Protopathic pain is conducted by what nerve fibers?
A-delta and C nerve fibers (noxious)
What is epicritic sensation?
Non-noxious: touch, pressure, proprioception, temperature
What is a rhizotomy?
Transection of dorsal nerve root of the spinal cord
Why do you have continued pain after rhizotomy?
- Some C fibers enter the ventral nerve root
2. 1st order neurons can travel up or down 3 segments in Lissaur’s tract
Where do opioids primarily act upon in the pain pathway?
Dorsal horn of the spinal cord
What are wide dynamic range neurons responsible for?
Central sensitization of pain secondary to “wind up” (repeated stimulation leading to huge pain transduction)
What nerve fibers carry fast pain?
A-delta fibers (myelinated)
What nerve fibers carry delayed pain?
C fibers
How do NSAIDs and aspirin help with pain?
Decreases prostaglandin formation which is responsible for nociceptor sensitization
How does peripheral sensitization occur?
Chemical mediators (bradykinin, prostaglandins, substance P, etc.), heat, frequency of stimuli
How does central sensitization occur?
Wind up (repeated stimulation leading to a huge increase in pain transduction) and neurochemical mediators (CGRP, substance P, etc.)
Mechanism of action for tramadol?
Weak mu-receptor agonist, increased serotonin release, decreased NE reuptake, NMDA receptor antagonist, capsaicin (VR1) receptor agonist
What treatment option can prevent the pain syndrome of post-herpetic neuralgia?
Epidural anesthesia (sympathectomy) since post-herpetic neuralgia has a sympathetic component
CRPS I vs II
I: Reflex sympathetic dystrophy
II: Causalgia
When would you use an EMG for CRPS?
To differentiate between CRPS I and II (abnormal in II)
Progression of CRPS can be evidenced by: increased opioid use, warm/red extremities, osteoporosis, sweat testing, EMG
Osteoporosis (stage 2 of CRPS)
Most effective treatment for early CRPS?
Stellate ganglion blocks (~3-12 injections)
Which gender is more prone to developing CRPS?
Women (3:1)
Treatment for phantom limb pain?
Anticonvulsants, TCAs, Alpha-2 agonists, NMDA antagonists, opioids
What type of anesthesia should be avoided in patients with phantom limb pain?
Spinal anesthesia
Definition of dysasthesia
Unpleasant sensation with or without a stimulus
Definition of anesthesia dolorosa
Pain in an area that lacks sensation
Definition of neuralgia
Pain in the distribution of nerves
Definition of allodynia
Perception of non-noxious (epicritic) sensation as pain
