Managment of Chronic Pain Flashcards
Define I.A.S.P
An unpleasant sensory and emotional experience, associated with actual tissue damage, or described in terms of such damage
What is peripheral sensitisation
A reduction in the threshold of peripheral afferent nociceptors
What is central sensitisation
Increased excitability of spinal neurones Rewiring in the spinal cord Changes in the brain
What causes pain after injury?
Peripheral sensitisation Central sensitisation
What is seen in chronic regional pain syndrome?
Allodynia Hyperalgesia Swelling Blue, red, white Hair, nail changes Osteopenia
What are the different types of pain?
Nociceptive pain Neuropathic pain Inflammatory pain
What is nociceptive pain?
Pain from injury relayed through a normal nervous system
What is neuropathic pain?
Pain generated within the nervous system?
What are common descriptions of neuropathic pain?
Burning, shooting, tingling, sensitivity
What is seen on examination of a patient with neuropathic pain?
Sensory changes Allodynia Hyperalgesia
Define allodynia
Pain from a stimulus that is not normally painful e.g. cotton wool
Define hyperalgesia
More pain than expected from a painful stimulus e.g. pin prick
What are the common causes of neuropathic pain?
- Shingles, post herpetic neuralgia
- Surgery
- Trauma
- Diabetic neuropathy
- Amputation
Many of unknown origin
What agents can be used in the management of neuropathic pain?
- Tricyclic antidepressants (amitriptyline)
- Anticonvulsants (e.g. gabapentin)
- Opioids (morphine)
- NMDA antagonists (ketamine)
- Sodium channel blockers (lignocaine)
- Capsaicin
- GABA agonists (baclofen)
Which drugs/agents are more often used in children?
- topical levomenthol
- activator of transient receptor potential melastatin-8 (TRPM8) channels
- Topical capsaicin
- depletion of substance P=-a peptide that amplifies or excited most cellular processes
- Lidocaine (patch)
- tricyclics (usually amitriptyline)
- inhibit amine reuptake so enhancing inhibition from the brainstem to the spinal cord
- gabapentin or pregabalin
- GABA analogues blocking voltage dependent calcium channels
What kind of chronic pain may a cancer survivor have?
Post surgical pain
Chemotherapy induced painful peripheral neuropathies
Chronic graft vs host disease
Radiation induced pain syndromes
Hormonal therapies and arthralgias
What can be used for resistant pain?
TENS
Acupuncture
Nerve blocks
Intrathecal drug delivery systems
Spinal cord stimulation
SCN9A if absent there is __ ___
SCN9A is abnormal there is ______ ____
SCN9A if absent there is no pain
SCN9A is abnormal there is increased pain
What may occur as a result of an injury such as an ankle sprain?
Neurodegeneration
Axonal dropout in peripheral nerves
Fear of pain
Cytokine changes
What is the role of voltage gated sodium channels in chronic pain?
Painful and painless sodium channelopathies, alpha and beta subunits, 9 types in humans.
What does Nav 1.7 mutation cause?
SCN9A Paroxysmal extreme pain disorder
What does an issue with Nav 1.7 cause?
SCN9A Congenital inability to express pain
What does leaky Nav 1.7 cause?
Erthromalalgia– burning hands and feet
What happens after amputation?
Remapping
What are the side effects of opioids?
Hormonal (Adrenal, libido)
Immunomodulation
Hyperalgesia (OIH)
