Pain Flashcards
what is pain?
- unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage
what is physical impairment assumed to be directly proportional to?
- directly proportional to pain
do assumptions always match reality?
- assumptions do not always match reality
what is not always necessary for pain?
- tissue damage is not always necessary for pain
what do most cases of lower back pain episodes not start with?
- do not begin with a traumatic event
what is the onset of 2/3 of lower back cases?
- spontaneous
- no memorable onset
what other pain can occur expect for in damaged tissues? what is it?
- phantom pain
- when you feel pain in your missing body part after an amputation
how do you work out if the threat of damage is sufficient for pain?
- injury observation
what is pain sometimes seen as? what is important to consider?
- seen as therapeutic
- context is important e.g., scratch the itch
is tissue damage always sufficient for pain?
- no, tissue pain is not always sufficient for pain
what threat can reduce pain?
- threat of damage reduces pain
what do first hand experiences of threat trigger?
- triggers a fright/ flight/ fight response
what can be delayed?
- onset of pain can be delayed
what can the responses be? what is an example?
- fright/ flight/ fight responses can be analgesic
- I looked at my foot and saw I was missing toes
is tissue damage always a threat?
- not always viewed as a threat
- context is important e.g., tattoo, gym
what percentage of asymptomatic adults have physical impairments in their spine?
> 30%
what is spinal pain associated with?
- associated with prevalence of disc pathologies
what are the four primary mechanisms of pain?
- nociceptive pain
- neuropathic pain
- inflammatory pain
- nociplastic pain
do the pain mechanisms work in isolation?
- can work in isolation or pain can be a result of a combination
what is the physiology of nociceptive pain?
- normal/ adaptive physiology
what does nociceptive pain start with? what can this be?
- starts with a noxious stimulus in the periphery
- stimulus either temperature, mechanical or chemical
what happens to the stimulus in nociceptive pain? what does it stimulate?
- carried by nociceptor sensory neuron to spinal cord
- stimulates an action potential that may or may not cause pain
what kind of response is nociceptive pain?
- autonomic response
what reflex is nociceptive pain involved in?
- withdrawal pain
what are two examples of nociceptive pain?
- tissue injury
- tissue deformation
what is the physiology of neuropathic pain?
- abnormal/ maladaptive
what does neuropathic pain damage?
- damages the nervous system
what types of pain does neuropathic pain involve? (2)
- spontaneous pain
- pain hypersensitivity
what are the three most common neuropathic pain conditions?
- sciatica
- spinal stenosis
- radiculopathy
where is the pain in sciatica?
- lumbosacral nerve root/ radicular pain
what is sciatica most commonly secondary to? (2)
- secondary to a disc prolapse or bulge
who is spinal stenosis common in?
- common in older age (60+ )
what is radiculopathy?
- radicular pain plus conduction loss
what is the physiology of inflammatory pain?
- local is normal and adaptive physiology
- systemic is abnormal and maladaptive physiology
what cells does inflammatory pain involve?
- macrophage
- mast cell
- neutrophil
- granulocyte
what pain types does inflammatory pain involve? (2)
- spontaneous pain
- pain hypersensitivity
what is a pain threshold?
- lowest intensity at which a given stimulus is perceived as painful
what is pain tolerance?
- maximum amount of pain a person can tolerate
what is a reduced pain threshold called?
- allodynia
what is an increased response called?
- hyperalgesia
what is the main example of an inflammatory pain condition?
- axial spondylarthritis
what are the main symptoms of axial spondylarthritis? (4)
- early morning stiffness and pain, wearing off or reducing during the day with exercise
- weight loss
- fatigue / tiredness
- feeling feverish and experiencing night sweats
when do people with axial spondylarthritis feel better and worse?
- feel better after exercise
- feel worse after rest
what is the onset of back pain like in axial spondylarthritis?
- slow or gradual onset of back pain and stiffness over weeks/ months rather than hours/ days
how long does symptoms of axial spondylarthritis persist?
- persistence for more than 3 months
what are the two techniques involved in the diagnosis of axial spondylarthritis ?
- blood tests
- imaging (spine and pelvis)
what two factors are picked up on in blood tests for axial spondylarthritis?
- C reactive protein
- HLA-B27
what are the two imaging techniques that could be used in the diagnosis of axial spondylarthritis?
- X- ray
- MRI
what is the physiology of nociplastic pain?
- abnormal and maladaptive physiology
what is nociplastic pain?
- chronic pain with altered nociception
- dynamic interplay of mechanisms causing or amplifying pain
what is abnormal in nociplastic pain?
- central processing is abnormal
what two factors does an abnormal central processing in nociplastic pain cause?
- increased facilitation
- decreased inhibition
what is the most common nociplastic pain condition?
- fibromyalgia
what is fibromyalgia a combination of? (2)
- facilitated sensitisation
- ineffective inhibition/ modulation/ habituation
what are the multiple protective symptoms of fibromyalgia? (3)
- widespread/ multi site pain
- allergies
- anxiety
what are the four other symptoms of fibromyalgia?
- cognitive symptoms
- unrefreshed sleep
- fatigue
- multiple somatic symptoms
which pain mechanisms are always persistent?
- neuropathic
- inflammatory
- nociplastic
what can neuropathic pain be?
- can be self limiting
what is the pain described as when systemic inflammatory pain?
- progressive
what is nociception?
- neural processes of encoding, transmitting and processing noxious stimuli
what is a noxious stimulus?
- actually or potentially tissue damaging event transduced or encoded by nociceptors
what are nociceptors?
- sensory receptor that is capable of transducing, encoding and transmitting noxious stimulus
what are the two fibres involved in nociception?
- a delta fibres
- C fibres
which fibre is myelinated? which is unmyelinated?
- myelinated A delta fibres
- unmyelinated C fibres
what does transduction involve?
- mechanical, thermal or chemical energy is transduced by specialised endings of A delta fibres and C fibres
how many stimuli do nociceptors respond to?
- some respond to just one stimulus modality
- others respond to multiple stimuli
what are the nociceptors that respond to multiple stimuli called?
- polymodal
what are some nociceptors before inflammation?
- some are silent or sleeping
- woken up by inflammation
what is stimulus intensity proportional to in encoding?
- stimulus intensity is proportional to pain intensity
how is stimulus intensity proportional to pain intensity?
- stimulus intensity is encoded to be proportional to nociceptor firing/ discharge frequency
what is nociceptor decoded to be?
- nociceptor firing frequency is decoded to be proportional to pain intensity
where does conduction in nociception occur?
- conducted along nerve fibre axons
what speed do ad fibres travel at?
- fast
- 6 to 30ms- 1
what are ad fibres normally?
- sharper
what speed do C fibres travel at?
- slow
- 0.5 to 2 ms-1
what sensation do C fibres produce?
- dull achy sensation
where does transmission occur?
- transmitted to neurons in dorsal horn of spinal cord
which part of the spinal cord do ad fibres transmit to?
- lamina I
- laminae marginalis
what part of the spinal cord do C fibres transmit to?
- lamina II
- substantia gelatinosa
where is the nociceptive stimulus transmitted to from the dorsal horn? what are the two main sites?
- transmitted to higher centres
- primary somatosensory cortex (S1)
- sensory homunculus
what is the sensory homunculus?
- illustrates the amount of representation each part of the body has in the sensory cortex
- emphasis hand and face
what was the first written theory of pain?
- Descartes specificity theory
what did the specificity believe about the nervous system?
- believed that the nervous system is hard wired
how did the specificity theory propose that inputs travel?
- input of one kind travels along nerves specific to that kind of input
where do inputs terminate in the specificity theory?
- terminates in areas of brain specifically receptive to that input
what are the limitations of Descartes specificity theory? (5)
- unable to explain phantom pain
- bilateral pain is common
- local and remote pain
- local and remote sensitivity
- afferent impulses can be gated
what can nociception cause?
- local and remote pain
what does convergence allow?
- allows a neuron to receive input from many neurons in a network
what are the two main types of convergences?
- peripheral neuronal convergence
- central neuronal convergence
where does central neuronal convergence occur? (2)
- dorsal horn of spinal cord
- primary somatosensory cortex (S1)
when does the gate open in the pain gate theory?
- opens when impulses in nociceptors facilitate transmission
when does the gate close in the pain gate theory?
- gate closes when impulses from large myelinated fibres block nociception
how can nociception be modulated? (2)
- dorsal horns are active sites
- not passive transmission stations
what is the gate control theory seen as today?
- seen as incomplete
what was the most important contribution of the gate control theory?
- emphasised central mechanisms
how is the CNS since viewed after the gate control theory?
- viewed as an active system that processes sensory input
what can nociception generate? (2)
- local and remote sensitivity
what is an increased pain response to noxious stimuli?
- hyperalgesia
what is a pain response to innocuous stimuli called?
- allodynia
what are the three consequences that happens following a noxious stimulus?
- hyperalgesia from subsequent noxious stimulus (pinch)
- allodynia from subsequent innocuous stimuli (brush + press)
- receptive field expands (into lower extremity)
what is it called when receptive field expands into lower extremity?
- secondary hyperalgesia
