Pain Flashcards
How much more common is depression for those with persistent pain?
4x more common
What % of people with chronic pain will have another significant medical problem (i.e.: a co-morbidity)?
87%
What is pain?
an unpleasant sensory and emotional experience associated with actual or potential tissue damage
Noxious
poisonous or harmful
Hyperalgesia
heightened pain intensity as a response to noxious stimuli
Analgesia
absence of pain or inability to feel pain
Dysaesthesia
abnormal sensation felt when touched, caused by damage to peripheral nerves
Paraesthesia
abnormal sensation with no apparent physical cause (e.g.: tingling, pricking, chilling, burning or numb sensation)
Allodynia
innocuous (harmless) stimuli cause pain
Hyperpathia
exaggerated responses to painful stimuli
What is the physiology of pain?
- An irritation or injury is detected in the peripheral nervous system by special nerves (nociceptors).
- A nerve impulse is then generated, sending a pain impulse towards the CNS.
- The message is received by the brain where the extent and significance of the irritation or injury is interpreted, and pain is sensed.
What are nociceptors?
free nerve endings present in every tissue in the body except for the brain, which are activated by noxious stimuli
What are examples of noxious stimuli?
- Thermal: severe heat or cold
- Mechanical: trauma, disease, injury, hypoxia, ulceration, infection, peripheral nerve damage, inflammation, ischaemia
- Chemical: histamine, kinins, prostaglandins, which are released due to tissue damage and inflammation
What are the 3-linked neurones that make up the ascending pathway of pain?
- First-order neurons
- Second-order neurons
- Third-order neurons
What are first-order neurons?
travel from the nociceptors to the spine
What are second-order neurons?
travel upwards through the spinal cord towards the thalamus in the brain
What are third-order neurons?
run from the thalamus to the somatosensory area of the cerebral cortex
How is line communication maintained?
by neurotransmitters (such as Substance P + Serotonin)
What is the purpose of the descending pathway of pain?
to inhibit the sensation of pain
How is pain sensation inhibited?
- Special neuropeptides with analgesic properties are released
- Which bind with opiate receptors, present throughout the CNS
- Block the action of neurotransmitter Substance P
What are the 4 major categories of opiate receptor?
- mu (𝜇)
- 𝑘𝑎𝑝𝑝𝑎
- 𝑠𝑖𝑔𝑚𝑎
- delta.
What are the (3) ascending tracts of the spinal cord transmission pathway?
- Spinothalamic
- Spinoreticular
- Dorsal column - medial lemniscal system
What nerves are used to carry sensation from the head and oral cavity (trigeminal system)?
- Trigeminal nerve
- Facial nerve
- Glossopharyngeal nerve
- Vagus nerve
What are the (3) classifications of pain duration?
- Transient
- Acute
- Chronic
What are the (3) classifications of pain type?
- Nociceptive
- Inflammatory
- Neuropathic
What is nociceptive pain?
detection of a noxious stimulus by nociceptors (C fibre)
- e.g.: mechanical, inflammatory, ischemic
What is inflammatory pain?
pain signalling & transmission behaviour in the presence of an inflammatory process
What is neuropathic pain?
a specific type of pain which results from damage to the signalling & transmission of neurons both within and outside of the CNS
What is peripheral sensitisation?
caused by multiple chemical mediators from nerve tissue damage and inflammatory response
What is central sensitisation?
change in the sensitivity of the spinal cord synapses in the dorsal horn and upstream through the nervous system to the cortex
What are the (4) different sources of nociception?
- Cutaneous (superficial somatic)
- Deep somatic (bone, tendon + joint)
- Visceral (internal organs)
- Referred pain
Describe transient pain characteristics?
- Short duration
- No significant consequence
- Don’t seek medical attention
e.g: stubbed toe or cut finger
Describe acute pain characteristics?
- Severe sudden onset, but is intense and can be intolerable
- Could be associated to medical condition or injury
- Brain response is to achieve homeostasis by initiating autonomic response
Describe chronic (persistent) pain characteristics?
- Continues even though healing is complete
- No autonomic response
- Considered a ‘syndrome’ or medical condition in its own right
Where does the liver contribute to pain distribution?
- Right lower thoracic pain
- Right shoulder pain
- Right epigastric pain
- Joint pain/back pain
What are some identifiable features of visceral pain?
- Pain diffuses and is poorly defined
- Non mechanical pattern
- Associated autonomic responses (e.g.: palpitations, nausea, etc)
Where does the gall bladder contribute to pain distribution?
- Epigastric pain
- Right shoulder pain
- Right lower thoracic pain
Where does the pancreas contribute to pain distribution?
- Epigastric pain
- Left or right shoulder pain
- Mid-thoracic pain
Where does the stomach contribute to pain distribution?
- Mid-thoracic pain
- Epigastric pain
Where does the kidney contribute to pain distribution?
- Loin pain
- Lateral buttock & thigh pain
- Groin pain
- Lower quadrant abdominal pain
Where does the bowel contribute to pain distribution?
- Central & lower abdominal pain
- Lower-quadrant abdominal pain (left>right)
Where does the ovaries contribute to pain distribution?
Abdominal pain left or right mid-abdomen
Where does the uterus contribute to pain distribution?
- Central lower back pain
- Posterior thigh pain
- Abdominal pain
Where does the bladder contribute to pain distribution?
- Central suprapubic pain
- Central pain over sacrum
- Pain around gluteal crease (left or right, or both)
- Perineal pain
Where does the prostate contribute to pain distribution?
- Genital pain
- Lower back pain perineal pain
Where does the abdominal aorta contribute to pain distribution?
- Lower back pain
- Groin pain
What is nociception?
The process of encoding noxious stimuli
What is allodynia?
Pain due to a stimulus that doesn’t normally provoke pain
What is hyperalgesia?
Increased pain from a stimulus that normally provokes pain
What is central sensitisation?
Increased responsiveness of nociceptive neurons in the central nervous system to their normal or subthreshold afferent input
What is neuropathic pain?
Pain caused by a lesion or disease of the somatosensory nervous system
What is nociplastic pain?
Pain that arises from altered nociception despite no clear evidence of actual or threatened tissue damage causing the activation of peripheral nociceptors or evidence for disease or lesion of the somatosensory system causing the pain
What is chronic/persistent pain?
Pain that persists or recurs for longer than 3 months
Why do we not feel pain all the time?
- When the messages reach the spinal cord there is another gateway neurone.
- This second gateway neurone also needs stimulating to pass on the ‘danger’ response to the brain.
- However, the brain can block these messages from ascending.
- The brain decides whether to let messages through and once through what they mean and how best to deal with the information.
What is a normal pain response?
- Unpleasant sensation associated with actual or potential harm
- Caused by stimulation to mechanical, chemical and thermal receptors.
- Receptors are stimulated and ion channels open.
- Positive ions enter the neurone if a threshold reached - action potentials created.
- The action potential travels along the nerve to the spinal cord.
What changes in persistent pain?
- ‘Danger’ system becomes more sensitive + better at passing on messages.
- Thresholds that trigger responses are lowered causing hypersensitivity and allodynia.
- Non-nociceptive neurones sprout new neurones near synapses + start taking ‘danger’ messages to the brain.
- Spinal cord amplifies the information going up to the brain + can make it up
- Unsurprisingly the brain thinks the danger level has increased (so increases pain sensation)
- Thoughts start to influence pain (the endocrine + immune systems get involved)
What is the role of a physio in pain management?
- Assessment
- Treatment and needed
- Red flag assessment
- Pain education / demystifying pain
- Goal setting
- Encourage self management
- Onwards referral to pain specialist
Describe a pain assessment.
- Subjective ratings scales: VAS, NRS, faces pain scales
- Objective measures: McGill pain questionnaire, Pain beliefs and attitudes inventory, EQ-5D
- Visual observations: pain behaviours, communication changes
- Physiological responses: HR, BP, sweating, colour
What factors affect pain?
- Anatomy / pathology
- Mood
- Sleep
- Stress
- Environment
- Lifestyle eg work
- Upbringing / childhood
- Past experiences
- Friends / family reactions
What may we offer our patients advice on?
- Pain management
- Pain education
- Pacing
- Postural advice
- Workstation advice
- Manual handling
- General activity and exercise
- Pathology education
Describe the ascending system of pain?
- Nociceptors are stimulated due to extremes of hot, cold, mechanical or chemical (inflammatory) stimuli
- Sensory nerves carry the information to the dorsal horn of the spinal cord
- This synapses with the ‘second order neuron’ which relays the signal to the Thalamus via the spinothalamic tract
