Physiology and Pathophysiology of Pain

Question 1

Where is nociception detected and how is it transmitted?

Answer 1

Detected in periphery and transmitted to spinal cord via first order neurons

Question 2

Where is nociception processed?

Answer 2

In the dorsal horn of the spinal cord

Question 3

How is nociception transmitted to the thalamus?

Answer 3

Through the brainstem and midbrain via second order neurons

Question 4

What is mediated in the thalamus?

Answer 4

Perception, learning and response

Question 5

Pain is modulated via the

Answer 5

descending tracts

Question 6

Descending pain-modulatory neurons are in the

Answer 6

medulla

Question 7

Descending pain-modulatory neurons inhibit

Answer 7

nociceptive transmission

Question 8

Through what mechanisms do descending pain-modulatory neurons inhibit nociceptive transmission?

Answer 8

Direct inhibition of projection neurons
Inhibition of transmitter release from primary afferents
Excitation of inhibitory interneurons
Inhibition of excitatory interneurons

Question 9

Opioid peptide synthesising cells and opioid receptors are distributed throughout

Answer 9

the pain modulating circuit

Question 10

Where are endogenous opioid ligans released and what can they produce?

Answer 10

Released at spinal sites

Can produce an analgesic effect

Question 11

How do endogenous opioid ligans work?

Answer 11

Reduce transmitter release from dorsal horn terminals of primary afferent nociceptors
Direct post-synaptic inhibition of central neurons that are activated by noxious stimuli

Question 12

Opioid receptor agonists block

Answer 12

excitatory amino acid release from primary afferents

Question 13

Endogenous opioids also contribute to modulation by inhibiting

Answer 13

neuropeptide release from primary afferents

Question 14

Ions which provide the energy needed for the transmission of pain signals are transmitted by

Answer 14

sodium and calcium channels

Question 15

If more receptors are activated and more ions transmitted, what effect will this have on the pain felt?

Answer 15

More pain will be felt

Question 16

Features of acute pain

Answer 16

Physiological
Presence of noxious stimuli
Serves protective function
Usually nociceptive

Question 17

Features of chronic pain

Answer 17

Pathological
Presence of noxious stimuli not essential
Does not serve any purpose
Nociceptive, neuropathic or mixed

Question 18

Nociceptive pain is a sensory experience that occurs when

Answer 18

specific peripheral sensory neurones respond to noxious stimuli

Question 19

In nociceptive pain, the painful region is typically localised at

Answer 19

the site of the injury

Question 20

Neuropathic pain is initiated/caused by

Answer 20

a primary lesion or dysfunction in the somatosensory nervous system

Question 21

Neuropathic pain occurs in

Answer 21

the neurological territory of the affected structure

Question 22

Treatment options for transduction of pain

Answer 22

NSAIDs
Ice
Rest - immobilise region of pain
Local anaesthetic blocks

Question 23

Treatment options for transmission of pain

Answer 23

Nerve blocks
Drugs e.g. opiods, anticonvulsants
Surgery e.g. cordotomy

Question 24

Treatment options for perception of pain

Answer 24

Education 
Cognitive behavioural therapy
Distraction 
Relaxation 
Graded motor imagery 
Mirror box therapy 
Psychological therapies

Question 25

Treatment options for descending modulation of pain

Answer 25

Placebos
Drugs e.g. opioids, anti-depressants
Surgery e.g. spinal cord stimulation