Management of Chronic Pain

Question 1

what is pain?

Answer 1

an unpleasant sensory and emotional experience, associated with actual tissue damage or described in terms of such damage

Question 2

what fibres transmit painful stimulus from skin to spinal cord?

Answer 2

a-delta

c-fibre

Question 3

what is released in spinal cord?

Answer 3

substance P and glutamate released to lamina I and V

Question 4

what in the brain in associated with sensory pain perception?

Answer 4

lamina V projects stimulus to thalamus which signals to somatosensory cortex

Question 5

what in the brain is associated with affective pain perception (attention to pain)?

Answer 5

lamina I projects stimulus to parabrachial which signals to amygdala hypothalamus

Question 6

peripheral tissue injury changes the nervous system in what two ways?

Answer 6

peripheral sensitisation - a reduction in the threshold of peripheral afferent nociceptors

central sensitisation - increased excitability of spinal neurones, rewiring in spinal cord and changes in the brain

Question 7

what are 6 characteristics of chronic regional pain syndrome?

Answer 7

allodynia 
hyperalgesia 
swelling 
colour changes 
hair and nail changes 
osteopenia

Question 8

what is nociceptive pain?

Answer 8

pain from injury relayed through a normal NS

Question 9

what is neuropathic pain?

Answer 9

pain generated within nervous system

Question 10

what does neuropathic pain feel like?

Answer 10

burning, shooting, tingling, sensitivity

Question 11

what is seen on examination in neuropathic pain?

Answer 11

sensory changes

• allodynia (pain from stimulus that not normally painful eg cotton wool)
• hyperalgesia (more pain than expected from painful stimulus eg pin prick)

Question 12

what are common causes of neuropathic pain?

Answer 12

shingles
post herpetic neuralgia 
surgery 
trauma 
diabetic neuropathy 
amputation 
many unknown origin

Question 13

how can neuropathic pain be biologically managed?

Answer 13

tricyclic antidepressants - amitriptyline

anticonvulsants - gabapentin

also opioids, NMDA antagonists, sodium channel blockers, capsaicin and GABA agonists

Question 14

what drugs are more often used in children?

Answer 14

topical levomenthol

topical capsaicin

lidocaine patch

tricyclics - amitriptyline

gabapentin or pregabalin

Question 15

what can cause chronic pain in cancer survivor?

Answer 15

post surgical pain 
chemo induced peripheral neuropathy 
chronic graft vs host disease
radiation induced pain 
hormonal therapy and arthralgias

Question 16

other than medication, what else could be used in chronic pain?

Answer 16

TENS
acupuncture 
nerve blocks 
intrathecal drug delivery systems 
spinal cord stimulation

Question 17

what gene could contribute to chronic pain?

Answer 17

SCN9A if absent - no pain

SCN9A if abnormal - increased pain

Question 18

what are potential side effects of opioids?

Answer 18

hormonal (adrenal, libido)
immunomodulation
hyperalgesia (OIH)