pain/ case 2 Flashcards
What is pain?
unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage
what are nociceptors?
sensory receptors that are activated by noxious stimuli that damage or threaten body’s integrity
What fibres do nociceptive terminals belong to?
A delta or C fibres
What stimuli are nociceptors sensitive to?
mechanical, thermal and chemical stimuli
What are the five stages of nociception and pain?
detection transduction conduction transmission modulation perception
what happens in transduction of pain?
physical stimuli into electrical stimuli: release of inflammatory mediators which bind to nociceptors converting thermal, mechanical or chemical stimuli into an electrical signal
What happens during conduction of pain?
AP up peripheral nerve to spinal nerve
What happens during transmission of pain?
release of neuropeptides which causes activation of spinal cord (second order neurone)
Which are the spinal tract that are involved in transmission of pain?
spinothalamic
spinoretincular
spinomesencephalic
What is modulation of pain?
nociceptive traffic modulated by excitatory and inhibitory efferents on the somatosensory system
(modulation can mean difference between gain and loss of function)
What is perception in pain?
nociceptive traffic filtered through individuals genetics, gender, cognition, affect, environment and previous pain experiences
What are the neurotransmitters involved in the transmission of pain at the second order neurone?
glutamate
substance P
CGRP (calcitonin gene related peptide)
What are the silent polymodal nociceptors?
usually silent but will get activated if there is information present (inflammation) (reps,d to thermo, mechano and chemical stimuli = polymodal)
What re the three main groups of sensory neurones?
Aalpha/Abeta fibres
Adelta fibres
C fibres
What is the function Aalpha/Abeta neurones?
proprioception
low threshold mechanoreception
What is the cell body diameter of Aalpha/Abeta neurones?
large (40-80 micrometers)
Are the Aalpha/Abeta neurones myelinated and what is the nerve conduction velocity?
yes
fast 40-120 m/s
What is the function of Adelta neurones?
- -> pain
- high threshold mechanoreception (touch and pressure)
What is the cell body diameter of Adelta neurones?
small-medium (15-50 micrometers)
Are the Adelta neurones myelinated and what is the nerve conduction velocity?
yes thinly
medium (10-30 m/s)
What is the function of C fibres?
- -> pain
- thermoreception
- high threshold mechanoreception, thermoreception and chemoreception
- silent polymodal nociception
What is the cell body diameter of C fibres?
small (10-25 micrometers)
Are the C fibres myelinated and what is the nerve conduction velocity?
no
slow (0.5-2 m/s)
What are the different types of pain?
- acute nociceptive
- inflammatory
- neuropathic
What is inflammatory pain?
- active inflammation
- sensitisation (= evoked by low and high intensity stimuli)
Why is inflammatory pain useful?
adaptive
protective during healing response
it is reversible
Why is acute pain useful?
high threshold stimulus dependent pain –> adaptive and serves as protective purposes
What is neuropathic pain?
pain caused by a lesion or disease oft somatosensory nervous system
What classifies pain as neuropathic?
- marked neuroimmune component
- sensitisation (SPONTANEOUS and evoked by low and high intensity stimuli)
Why is neuropathic pain bad?
- maladaptive and persistent
- abnormal amplification
- serves no useful purpose
- not well managed
What are the clinical features of neuropathic pain?
- stimulus evoked pain
- hyperalgesia
- allodynia - spontaneous pain
- described as burning, tightness accompanied with parasthesia, tingling shooting or stabbing - associate with coborbidities such as anxiety, depression and sleep-disturbances