Pain

Question 1

Mechanism of action of gabapentin

Answer 1

Inhibit alpha 2 delta subunit on voltage gated calcium channels in CNS

Reduces excitatory neurotransmitter release

Question 2

Mechanism action TCA

Answer 2

TCA sodium channel blocker

Anticholinergic effects

Question 3

Diagnosis of complex regional pain syndrome

Answer 3

Pain lasting longer than expected /greater than expected

Pain cannot be explained by another cause

Budapest criteria
Must report 1 symptom in each category
Must display at least one sign in two or more category

Question 4

Types of complex regional pain syndrome

Answer 4

Type 1 - specific nerve not identified, tissue damage

Type 2 - specific nerve identified

Treatment same for both

Question 5

Budapest criteria categories and examples of symptoms in each

Answer 5

Vasomotor - temperature asymmetry skin colour
Sudomotor - odema sweating
Tropic/motor - decreased range of movement, nail and hair changes
Sensory - hyper aesthesia, allodynia

Question 6

Treatments for complex regional pain syndrome

Answer 6

Non pharmacological treatments 
Physio /Exercise programmes 
CBT / psychological support 
Pain management programme 
Support group 
Specialist input 
Early treatment 

Pharmacological treatment
Simple analgesic
Gabapentinoids
Tricyclics

Other
Spinal cord stimulator
Thoracic sympathectomy

Question 7

What is complex regional pain syndrome

Answer 7

Clinical disorder
Severe continuous pain
Accompanied by sensory, vasomotor, sudomotor, motor/tropic changes

Pain regionally restricted
Disproportionate to inciting event
Cannot be explained by another pathology

Question 8

Diagnosis of CRPS

Answer 8

Budapest or IASP criteria

Continuing pain disproportionate
Can’t be explained by anything else
Describes symptoms in 3 or 4 categories (4 for hip apes to)
Signs in at least 2 categories

Question 9

Differentials for CRPS

Answer 9

Neuropathic pain syndromes 
Ie peripheral neuropathy radiculopathy 
Vascular ie raynoauds 
Inflammation ie rheumatoid 
MSM ie repetitive strain fibromyalgia

Question 10

Pathophysiology of CRPS

Answer 10

?

Exaggerated inflam response increased IL6 and CRP
Neurogenic inflammation ie increased substance P
Autoimmune
Deep tissue microvascukar ischaemia repercussion
Genetics
Cortical reorganisation
Small fibre neuropathy
Psychological factors (although no association with onset and anxiety and depression)

Question 11

Treatment of CRPS

Answer 11

Physio 
Bisphosphomates (strong evidence) 
Ladder bar string opiods 
Gabapentin 
Low dose IV ketamine 
Cold CRPS calcium channel blocker or pde5 inhibitors 
IT Baclofen 
Psychological 

Invasive treatments
Sympathetic blockade
Scs

Vitamin c might help prevent