Analgesia

Question 1

Types of Pain

Answer 1

• Acute – tissue damage
• Chronic- beyond tissue damage

Neuropathic Pain: Ion Gate Malfunction, Nerve Damage, Neuralgia, Non-Nociceptive

Question 2

Nociceptive stimuli examples

Answer 2

• 5-HT (serotonin), migraines (indirect mechanism)
• bradykinin
• histamine
• capsaicin (from chillies)
• Prostaglandin (PGE2; hyperalgesia)
• ATP

Question 3

Peripheral Processing: Dorsal Horn of Spinal Cord

Answer 3

Afferent fibers
* myelinated A beta fibers; sharp intense pain (somatic)
* unmylinated C fibers; dull throbbing pain (visceral)
* Transmitters
* glutamate (AMPA, NMDA receptors)
* substance P

Question 4

Stages in pain processing

Answer 4

Peripheral
* dorsal horn of spinal cord
* inhibition/amplification

Central
* thalamus & reticular formation
* pain perception
* cortex & limbic system
* cognitive/emotional responses

Question 5

Pain Reception Process

Answer 5

1. tissue injury
2. local release of active factors (PG, BK, K)
3. Persistent activation/ sensitization of A beta/C
4. activity in ascending pathways & spinal facilitation
5. exaggerated output for given stimulus input
6. ongoing pain & hyperalgesia

Question 6

Mechanisms of Nerve Injury–Evoked Nociception Neuropathic Pain

Answer 6

1. Nerve Injury
2. peripheral neve degeneration
3. spontaneous afferent activity (a) or spinal sensitization (a/b)
   4a. spontaneous dysesthesias (shooting, burning pain)
   4b. spinal sensitization –> allodynia (light touch hurts)
   A) A beta afferent fibers –> allodynia (light touch hurts)