P: Drugs for Pain Management - Week 9 Flashcards
Provide 3 examples of how pain can cause profound changes in autonomic function
- heart rate
- blood pressure
- micturition
How does pain experience vary from person to person?
pain is uniquely individual and subjective
Define Acute Pain
Pain that has a recent onset and limited duration, usually due to an identifiable cause relatingto injury or disease
How can you classify acute pain. Provide and explain 2 classifications
- Somatic - sharp pain that is well localised
- Visceral - dull pain that is poorly localised
What percentage of people with chronic non-cancer pain gain access to effective care?
less than 10%
NAme the 3 broad groups of chronic persistent pain (classified based on cause)
- Define nociceptive basis - e.g. cancer
- Well-defined neurophathological basis- e.g. postherpetic neuralgia
- Idiopathic - e.g. chronic musculoskeletal pain
How long should pain be ongoing to be considered chronic persistent pain?
more than 3 months
In regards to nociceptive superficial somatic pain, describe:
- stimulus origin (4)
skin, subcutaneous tissue, mucosa of mouth
In regards to nociceptive superficial somatic pain, name an example
malignant ulcers
In regards to nociceptive superficial somatic pain, describe: symptoms (3)
- hot, burning, stinging
In regards to nociceptive superficial somatic pain:
- does it have sudomotor/vasomotor effects?
No
In regards to nociceptive deep somatic pain:
- describe stimulus origin (6)
bones, muscles, joints; organ capsules, pleura
In regards to nociceptive deep somatic pain:
- provide 2 examples
- bone metastases
- liver capsule distension or inflammation
In regards to nociceptive deep somatic pain:
- describe symptoms (2)
- does it have sudomotor/vasomotor effects?
dull, aching
sudomotor/vasomotor effects may occur
In regards to nociceptive visceral pain:
- describe stimulus orgin (2)
- solid or hollow organs
- deep tumour masses
In regards to nociceptive visceral pain:
provide 2 examples
- deep abdominal or chest masses
- intestinal, biliary colic
In regards to nociceptive visceral pain:
- describe symptoms (2)
- dull, deep
In regards to nociceptive visceral pain:
- does it have sudomotor/vasomotor effects? (4)
Yes. Nausea, vomiting, sweating, BP/HR changes
In regards to neuropathic pain:
- describe stimulus origin (1)
damage to nociceptive pathways
In regards to neuropathic pain:
- provide 2 examples
- tumour-related
- spinal cord compression
In regards to neuropathic pain:
- describe symptoms (6)
- “pins and needles”
- tingling
- burning
- shooting
- allodynia
- phantom pain
In regards to neuropathic pain:
- describe sudomotor/vasomotor effects
sudomotor/vasomotor instability: warmth, sweating, pallor, cold, cyanosis
Describe in 5 steps the pathway of the nociceptive circuit
- activation of the peripheral terminal by a noxious stimulus leads to action potentials
- conducted to the dorsal horn of the spinal cord
- the dorsal horn relays the signal to cns regions
- signal passes through brainstem areas, the thalamus and to the cortex of the brain, to action
- descending modulatory control pathway
Describe the activation of nociceptive neurons (3)
- a thermal, chemical or mechanical sensory event activates a specific peripheral receptor, leading to ion influx and depolarisation of the peripheral terminal
- the generator potential induced by the nociceptive signal leads to AP production if the threshold for activation of the voltage sensitive sodium channel is reached
- frequency and duration of APs in activated fibre transfer information to CNS re onset, intensity and duration of stimulus
In regards to neurotransmission in the spinal cord dorsal horn, what does the incoming AP from the periphery activate?
activates presynaptic voltage sensitive calcium channels leading to calcium influx and subsequent synaptic vesicle release
In regards to neurotransmission in the spinal cord dorsal horn: What do the released neurotransmitters act on?
postsynaptic receptors
In regards to neurotransmission in the spinal cord dorsal horn: what does stimulation of ionotropic glutamate R lead to?
fast postsynaptic depolarization
In regards to neurotransmission in the spinal cord dorsal horn: what does activation of other modulatory R lead to?
slower postsynaptic depolarization