NCS Pain Management in Neurology 2 — Questions and Answers
Question 1: A patient with central sensitization presents with allodynia. Which neuroplastic mechanism best explains this phenomenon?
- Peripheral nociceptor fatigue
- Wind-up and long-term potentiation in dorsal horn neurons (Correct answer)
- Reduced substance P release at the synapse
- Increased GABAergic inhibition in the spinal cord
Correct answer: Wind-up and long-term potentiation in dorsal horn neurons
Wind-up and LTP in dorsal horn neurons lower the activation threshold so normally non-painful stimuli become painful.
Question 2: Which opioid receptor subtype is primarily responsible for supraspinal analgesia?
- Kappa (κ)
- Delta (δ)
- Mu (μ) (Correct answer)
- Nociceptin/orphanin FQ (NOP)
Correct answer: Mu (μ)
Mu opioid receptors mediate the primary supraspinal analgesic effects and are the main target of most clinical opioids.
Question 3: A patient on long-term opioids requires escalating doses for the same pain relief. Which pharmacological process best describes this?
- Opioid-induced hyperalgesia
- Pharmacodynamic tolerance (Correct answer)
- Serotonin syndrome
- Physical dependence
Correct answer: Pharmacodynamic tolerance
Pharmacodynamic tolerance refers to reduced receptor responsiveness requiring higher doses to achieve the same analgesic effect.
Question 4: The 'gate control theory' of pain proposes that pain transmission is modulated at the level of the:
- Thalamus
- Periaqueductal gray
- Spinal cord dorsal horn (Correct answer)
- Primary somatosensory cortex
Correct answer: Spinal cord dorsal horn
The gate control theory posits that large-fiber (Aβ) activity can inhibit pain signal transmission via interneurons in the dorsal horn.
Question 5: Which descending pain modulation pathway utilizes serotonin and norepinephrine as primary neurotransmitters?
- Spinothalamic tract
- Dorsal column-medial lemniscal pathway
- Dorsolateral funiculus (PAG-RVM system) (Correct answer)
- Anterolateral system
Correct answer: Dorsolateral funiculus (PAG-RVM system)
The PAG-RVM-dorsolateral funiculus system uses serotonin and norepinephrine to exert descending inhibitory control over dorsal horn neurons.
Question 6: A neurologist prescribes duloxetine for a patient with diabetic peripheral neuropathy. What is the primary mechanism of analgesic action?
- Sodium channel blockade in peripheral nerves
- NMDA receptor antagonism
- Serotonin-norepinephrine reuptake inhibition enhancing descending pain modulation (Correct answer)
- COX-2 inhibition reducing prostaglandin synthesis
Correct answer: Serotonin-norepinephrine reuptake inhibition enhancing descending pain modulation
Duloxetine inhibits reuptake of serotonin and norepinephrine, strengthening descending inhibitory pathways that suppress pain signaling.
Question 7: In complex regional pain syndrome (CRPS), which finding differentiates Type I from Type II?
- Presence of allodynia
- Documented nerve injury in Type II (Correct answer)
- Sympathetically maintained pain in Type I only
- Skin temperature changes in Type II only
Correct answer: Documented nerve injury in Type II
CRPS Type II (formerly causalgia) is distinguished by a confirmed peripheral nerve injury, whereas Type I occurs without identifiable nerve damage.
NCS Pain Management in Neurology 2
A patient with central sensitization presents with allodynia.
Which neuroplastic mechanism best explains this phenomenon?