L15 - Pain 4 Flashcards
Chronic pain is a clinical classification identifying regular pain experienced for _ months or longer
3
Clinical pain treatment normally alleviates pain as a symptom without addressing underlying causes
Clinical pain treatment normally alleviates pain as a symptom without addressing underlying causes
What is affected in congenital analgesia?
Nav 1.7 and 1.9 - detects and transmits nociceptive info
PDRM12 - Essential for development of certain sensory neurons. Mutations lead to analgesia
TrkA - involved in maturation and differentiation of sensory neurons
NGF - needed for development of C-type primary afferent sensory fibres
Phenotype of PRDM12 mutations
As they cannot feel pain - they can cause damage to the tongue, lips, digits, extremities, corneal damage to eye
*Damage so severe that amputation is required
Erythromelalgia - what is it? Treatment? What mutation causes it?
Mild warmth induces intense, burning pain in affected extremities, severe redness (erythema), and increased skin temperature that may be episodic or almost continuous in nature.
Treatment - using cooling to decrease pain exacerbated by warmth
Two gain of function mutations in Nav1.8 voltage gated Na channel gene - channels are open for longer (activity of channel amplified) and threshold lower (quicker activation)
How is erythromelalgia a paradox?
Causes pain but also small fibre neuropathy in skin where there is a loss of nociceptive terminals in the skin (could be due to overactivity from too much Ca2+ entering nerver terminal)
Maladaptive pain
Alters nociceptive signal processing so that pain is felt in the absence of a stimulus, and responses to innocuous and noxious stimuli are enhanced.
Two groups of maladaptive pain
1) Neuropathic pain - neural lesion, positive and negative symptoms
2) Dysfunctional pain (no identifiable pathology) - no neural lesion, no inflammation, positive symptoms
Three types of neuropathic pain with different hypersensitivity
1) Trigeminal neuralgia - trigeminal nerves of front of face
2) Peripheral nerve injury - sensory loss and dysaesthesia (an abnormal unpleasant sensation felt when touched)
3) Central pain - allodynia
Can peripheral sensitization lead to central sensitization?
Inflammation of tissue increase spontaneous activity in nociceptors (peripheral sen.) -> leads to activity dependent plasticity in CNS (Central sen.)
Post-surgery, animals develop what kind of hyperalgesia?
Cold and mechanical hyperalgesia
*As it is a withdrawal reflex, also occurs in anesthetised animals
How do we assess pain in babies?
Facial expressions - brow bulge or eye squeeze
How do we assess pain in rodents?
Orbital tightening, nose bulge, cheek bulge, ear position, whisker change
Osteoarthritis starts off as inflammatory/nociceptive pain associated with structural damage to a joint. Over time there’s a development of central sensitization which can be recognised by the onset of referred pain away from the joint
Osteoarthritis starts off as inflammatory/nociceptive pain associated with structural damage to a joint. Over time there’s a development of central sensitization which can be recognised by the onset of referred pain away from the joint
What happens to pain sensitivity when you are sick?
It increases
