Pain

Question 1

What is the difference between nociception and pain?

Answer 1

Pain:
An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.

Nociception:
The neural process of encoding noxious stimuli.

Question 2

Name three different primary afferent neurons that transmit information about nociception.

Answer 2

Aβ fibers: Touch

Aδ fibers: first pain -> mechanical stimulus

C fibers: second pain -> noxious heat and chemical stimuli

Question 3

What four neurons are releasing neurotransmitters in the dorsal horn?

Answer 3

• Primary afferent neurons
• interneuron
• dorsal horn projection neuron (PN)
• descending regulatory neurons

Question 4

What is the difference between nociceptive pain and neuropathic pain?

Answer 4

Nociceptive pain arises from damage to non-neural tissue, whereas neuropathic pain is caused by lesions or disease of the somatosensory nervous system.

Question 5

What is sensitization and at which levels can this take place?

Answer 5

Periferal chronic pain trigger central pain mechanisms that amplify peripheral pain and generate additional central pain over time.

This pain amplification can happen at the level of the injury, and would be refered to as sensitisation.

Over time, it can also happen as central sensitisation at the segmental spinal level.

Chronic pain may lead to suprasegmental central sensitisation.

Suprasegmental central sensitisation may also happen without any peripheral tissue damage.

Question 6

What is the role of descending NE and 5HT upon pain management and what medication work upon this mechanism?

Answer 6

Descending NE and 5HT inhibits pain. Insufficient NE or 5HT may lead to pain -> SNRIs enhance NE and 5HT levels and work as pain medication. Also α2 adrenergic receptor agonists are useful for pain relieve.

Question 7

What is the working mechanism of TCA in pain medication?

Answer 7

Direct blockade of voltage-gated sodium channels to prevent AP of nociceptors.

Question 8

Explain the involved 5HT receptors involved in pain modulation.

Answer 8

5-HT exerts inhibitory actions via the 5-HT7 and 5-HT1 receptors and pain facilitations via 5-HT3 receptor activation.

Question 9

What is the mechanism of action of Gabapentanoids?

Answer 9

They bind to the alpha-2-delta subunit of voltage-sensitive calcium channels.

Alpha-2-delta ligands may bind to voltage-sensitive calcium channels in the dorsal horn to reduce
excitatory neurotransmission and alleviate pain.

Alpha-2-delta ligands may also bind to voltage-sensitive calcium channels in the thalamus and cortex to reduce excitatory neurotransmission and alleviate pain.

Question 10

What are overlaps between depression and pain?

Answer 10

-Decreased hippocampal and PFC volume which leads to increased limbic activity to unpleasant events.
-dysfunctional amygdala, increased response to stress or negative life events