Chronic Pain

Question 1

Define pain

Answer 1

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

Question 2

Describe the pain pathway

Answer 2

1. Stimulus
2. Skin (A alpha and C fibres)
3. Spinal cord (substance P glutamate)
4. Lamina 1-5
5. thalamus
6. somatosensory cortex

Question 3

What is the emotional role in the pain pathway?

Answer 3

After the spinal cord it travels to lamina 1 and the parabrachial region then the amygdala hypothalamus to get attention

Question 4

What two mechanisms change the peripheral nervous system after injury?

Answer 4

Peripheral sensitisation (reduced peripheral afferent nociceptors)
Central sensitisation (increased excitability, rewiring and brain changes)

Question 5

Describe chronic regional pain syndrome

Answer 5

Idiopathic but thought to have genetic factors. Often occurs after acute injury in hands and feet

Question 6

How does chronic regional pain syndrome present?

Answer 6

Allodynia, hyperalgesia, swelling, blue/white/red colouration, hair and nail changes, osteopenia

Question 7

Name three types of pain

Answer 7

• nociceptive
• neuropathic
• inflammatory

Question 8

What does neuropathic pain feel like?

Answer 8

Burning, shooting, tingling, sensitivity, sensory changes on examination

Question 9

Define allodynia

Answer 9

Pain from stimulus that is not normally painful

Question 10

Define hyperalgesia

Answer 10

More pain than expected from a painful stimulus

Question 11

What causes neuropathic pain?

Answer 11

Shingles, post herpetic neuralgia, surgery, trauma, diabetic neuropathy, amputation, unknown

Question 12

Name the drugs that can be used to treat pain

Answer 12

• tricyclic antidepressants (amitriptyline)
• anticonvulsants (gabapentin)
• opioids (morphine)
• NMDA antagonists (ketamine)
• Sodium channel blockers (lignocaine)
• Capsaicin
• GABA agonist (baclofen)

Question 13

What therapies can be used in children?

Answer 13

Topical levomenthol, capsaicin, lidocaine, oral tricyclines, gabapentin or pregablin

Question 14

Name some non-oral methods to treat pain

Answer 14

TENS machine 
Acupuncture 
Nerve blocks 
Intrathecal drug delivery 
Spinal cord stimulation 
Lidocaine
Epidural steroids 
Facet denervation after test

Question 15

What type of channelopathy can cause pain problems?

Answer 15

Voltage gated sodium channels

Question 16

What can SCN9A cause?

Answer 16

Paroxysmal extreme pain disorder

Congenital inability to express pain

Question 17

What is erythromyalgia?

Answer 17

Burning in hands and feet