Chronic Pain Flashcards
What laminae in the spinal cord are involved in chronic pain?
Lamina 1
Lamina 5
Which neuronal fibres are involved in pain transmission?
A-delta
C-fibre
Which neurotransmitters are involved in pain transmission?
Substance P
Glutamate
Which areas of the brain are involved in the emotional side of pain?
Amygdala and hypothalamus
What are the 2 mechanisms to pain after an injury?
Peripheral sensitisation; a reduction in the threshold of peripheral afferent nociceptors
Central sensitisation; increased excitability of spinal neurones, rewiring in the spinal cord, changes in the brain
What are the symptoms of chronic regional pain syndrome?
Allodynia Hyperalgesia Swelling Blue, red, white skin Hair and nail changes Osteopenia
What is nociceptive pain?
Pain from injury relayed through a normal nervous system
What is neuropathic pain?
Pain generated within the nervous system
How is neuropathic pain diagnosed?
History Description; burning, shooting, tingling, sensitivity Exam; sensory changes Allodyina Hyperalgeisa
What are common causes of neuropathic pain?
Shingles, post herpetic neuralgia Surgery Trauma Diabetic neuropathy Phantom limb
Management of neuropathic pain
Tricyclic antidepressants Anticonvulsants Opioids NMDA antagonists; ketamine Na+ channel blockers; lignocaine Capsaicin GABA agonists; baclofen
What is the mode of action of capsaicin?
Depletion of substance P
What is the mode of action of tricyclics?
Inhibits amine reuptake and so enhances inhibition from the brainstem to the spinal cord
What is the mode of action of gabapentin/pregabalin?
GABA analogues blocking voltage dependent calcium channels
What are common side effects of opioid overuse?
Hormonal; adrenal, libido
Immunomodulation
Hyperalgesia; opioid induced hyperalgesia
