What is pain and why should we treat it? Classification of pain Flashcards
What is pain?
An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.
Unpleasant.
Emotions are important.
The cause is not always visible. Pain is what the patient says hurts.
What are the benefits of treating pain for the patient?
Physical:
improved sleep,
better appetite;
fewer medical complications, e.g. heart attack, pneumonia.
Psychological:
reduced suffering;
less depression, anxiety.
What are the benefits of treating pain for the family?
Improved functioning as a family member, e.g. as a father or mother.
Able to keep working.
What are the benefits of treating pain for society?
Lower health costs, e.g. shorter hospital stay. Able to contribute to the community.
How is pain classified?
Duration: acute, chronic, acute or chronic.
Cause: cancer, non-cancer.
Mechanism: nociceptive, neuropathic.
Acute vs. chronic pain.
Acute:
pain of recent onset and probable limited duration.
Chronic:
pain lasting for more than 3 months;
pain lasting after normal healing;
often no identifiable cause.
Cancer vs. non-cancer pain.
Cancer pain:
progressive,
may be mixture of acute and chronic.
Non-cancer pain:
many different causes,
acute or chronic.
What is nociceptive pain?
Obvious tissue injury or illness.
Also called physiological or inflammatory pain.
Protective function.
Description:
- sharp ± dull,
- well localised.
What is neuropathic pain?
Nervous system damage or abnormality.
Tissue injury may not be obvious.
Does not have a protective function.
Description:
- burning, shooting ± numbness, pins and needles,
- not well localised.
What is acute non-cancer pain?
e.g. due to fracture, appendicitis.
Symptom of tissue injury or illness.
Usually nociceptive.
Occasionally neuropathic (e.g. sciatica).
What is chronic non-cancer pain?
e.g. chronic back pain, arthritis.
Injury may not be obvious.
Complex, may be mixed nociceptive and neuropathic.
Does not respond to usual drug treatment.
What is cancer pain?
e.g. uterine cervical cancer, breast cancer.
Features of acute and chronic pain.
Often mixed nociceptive and neuropathic pain.
Usually gets worse over time if untreated.
Pain…
- is always subjective
- unpleasant sensation and emotional experience
- pain may be present in the absence of tissue damage
- may have a protective function
- all are true
all are true
Hyperalgesia:
a) is associated with normal function of nociceptors
b) is increased pain from a stimulus that normally provokes pain
c) is pain due to a stimulus that does not normally provoke pain
d) is a characteristic feature of nociceptive pain
e) abnormally painful reaction to repetitive stimulus and increased threshold.
Is increased pain from a stimulus that normally provokes pain.
Nociceptors
is associated with direct activation of ion channels
a low threshold is required for activation
the stimulus stops in the spinal cord
nociceptive response is due to a non nauxious stimulation
typically involves a single neurotransmitter
is associated with direct activation of ion channels
Allodynia is:
a) diminished pain in response to a normally painful stimulus
b) increased pain from a stimulus that normally provokes pain
c) pain due to a stimulus that does not normally provoke pain
d) abnormal sensation, whether spontaneous or provoked
e) all are false
Pain due to a stimulus that does not normally provoke pain.
What should be the medical professional’s approach to pain?
Recognise: does the patient have pain? do other people know the patient has pain? Assess: how severe is the pain? what type of pain is it? are there other factors? Treat: what non-drug treatments can I use? what drug treatments can I use?
What is nociception?
How signals get from the site of injury to the brain. Nociception is not the same as pain.
You can have nociception without pain
What is pain perception?
How we ‘feel’ pain.
What factors influence pain perception?
Beliefs/concerns about pain.
Psychological factors: anxiety, anger, depression.
Cultural issues: language, expectations.
Other illnesses.
Coping strategies.
Social factors, e.g. family, work.
What are the 4 steps in the physiology of pain?
Periphery:
- tissue injury;
- release of chemicals;
- stimulation of pain receptors (nociceptors);
- signal travels in A delta or C nerve to spinal cord.
Spinal cord:
- dorsal horn is the first relay station;
- A delta or C nerve synapses with second nerve;
- second nerve travels up opposite side of spinal cord.
Brain:
- thalamus is the second relay station;
- connections to many parts of the brain (cortex, limbic system, brainstem);
- pain perception occurs in the cortex.
Modulation:
- descending pathway from brain to dorsal horn;
- usually decreases pain signal.
Why is pain physiology important?
- Many factors affect how we ‘feel’ pain:
- psychological factors are very important.
- Different treatments work on different parts of the pathway:
- more than 1 treatment may be needed.
What is pain pathology?
Abnormal processing of pain signal.
Nervous system damage or dysfunction.
Needs to be treated differently.
e.g. nerve trauma, diabetic pain (damage); fibromyalgia, chronic tension headache (dysfunction).
