Chronic Pain Management (Exam II) Flashcards
What are the 4 steps of the pain process?
Transduction
Transmission
Modulation
Perception
_______ is a reduced threshold to painful stimulus.
Allodynia
______ is an increased response to painful stimulus.
Hyperalgesia
What are the excitatory neurotransmitters relevant to the process of pain transduction?
- Glutamate
- CGRP
- NGF
- Substance P
What is the “order” of the afferent pain transmission pathway?
1st order neuron → 2ⁿᵈ order neurons → 3ʳᵈ order neurons
What are first order neurons?
Periphery → dorsal horn (cell bodies to dorsal root ganglion)
What are 2ⁿᵈ order neurons?
Dorsal horn to thalamus
What are third order neurons?
Thalamus to cerebral cortex
What is the most important site of pain modulation?
Substantia Gelatinosa of the dorsal horn
What CNS structure modulates pain by acting on the substantia gelatinosa?
DIC (Descending Inhibitory Complex)
Where does the Descending Inhibitory Complex originate and end?
Periaqueductal gray matter & rostroventral medulla → substantia gelatinosa
Pain is inhibited when spinal neurons release _____ and ______.
GABA & glycine
Pain is inhibited when the descending inhibitory pain pathway releases….
NE, 5-HT, and endorphins
What are the three mechanisms behind facilitation (intensification) of painful stimuli?
- Wind-up (sensitization) of 2ⁿᵈ order neurons
- Reception field expansion
- Hyperexcitability of reflexes
What drugs can be used to attenuate pain at the level of transduction?
- NSAIDs
- Opioids
- LA’s
- Antihistamines
What drugs can be used to attenuate pain at the level of transmission?
- LA’s
- Opioids
What drugs can be used to attenuate pain at the level of modulation?
- Opioids
- α2 agonists
- NMDA Antagonists
What drugs can be used to attenuate pain at the level of perception?
- Opioids
- α2 agonists
- General Anesthetics
What are the two types of acute nociceptive pain?
Somatic & Visceral
What are the two types of somatic pain?
Superficial
- Well localized
- Input from skin, SQ, mucous membranes
Deep
- muscles, tendons, bones
- dull, aching, less localizable
What is visceral pain?
From disease process or abnormal organ function from organ tissue or tissue covering the organ
Visceral pain that can be better localized to the organ is known as ______ pain.
Parietal
What are the two types of chronic pain?
Malignant (related to cancer)
Non-malignant (neuropathic, musculoskeletal, inflammatory)
What is repeated stimuli reducing threshold of primary afferent nociceptors progressively?
Sensitizaiton
What are risk factors for developing Complex Regional Pain Syndrome (CRPS)?
- Previous trauma/surgery
- Nerve Injury (Type II)
- Work related injury
- Female
What are the two types of CRPS?
- Type I (Reflex Sympathetic Dystrophy)
- Type II (Causalgia)
What is the difference between Type I & Type II CRPS?
Both the same except Type II has a documented prior nerve injury.
What is CPSP?
Complex Post-Surgical Pain
- Difficult to control acute pain postoperatively
- Can be unresponsive to opioids
Chronic Pain Chart
What drug classes are the firstline therapy for treatment of chronic pain?
TCA’s
SNRI’s
What anticonvulsants are commonly prescribed for chronic pain?
- Gabapentin
- Pregabalin
- Carbamazepine
What is the max daily dose for gabapentin?
3600 mg
What is the max day dose for pregabalin?
600mg
What is a commonly used medication for post-herpetic neuralgia?
Lidocaine patches
How do capsaicin patches treat nerve pain?
Long-term exposure causes overstimulation → depletion of substance P and desensitization of nerve
What is generally considered a second line treatment in most guidelines?
Tramadol
Weak μ-opioid agonist & SNRI.
What are third-line procedural therapies for chronic pain?
- Interventional pain management (Somatic blocks, sympathetic blocks)
- Implantable stimulators (spinal, deep brain)
- Epidural (steroids, ablation)
In addition to NMDA antagonism, what else is inhibited via ketamine?
Astrocyte activation
Targeted drug delivery involves the delivery of medications directly to the…
dorsal horn
What meds are typically used in pain pumps?
Morphine
Ziconitide
How do TCA’s work?
- Inhibition of serotonin & NE reuptake
- Blockade of histamine, catecholamines, ACh, and Na⁺ channesl
