PAIN AND ADDICTION Flashcards
what are the four parts of pain communication?
transduction
transmission
perception
modulation
On what types of sensory neurone have nociceptive function?
a delta fibres
c fibres
Which sensory neurone has the fastest conduction speed?
a alpha fibres
what is the function of a alpha fibres?
proprioception
sensory relay from golgi tendon organ
what is the function of a delta fibres?
NOCICEPTION (mechano and thermal)
what is the function of a beta fibres?
touch
what is the function of C fibres?
NOCICEPTION (mechano, thermal and chemical)
which is the only fibre type to sense chemical stimuli?
C fibres
which sensory fibre has the slowest rate of conduction?
C fibres
which sensory fibre is non-myelinated?
C fibres
what receptors on axons of 1st order sensory neurones are activated in response to heat?
TRPV1 receptor
what is acute nociceptive pain?
high threshold, stimulus dependent pain
designed to warn away from painful stimuli
what is inflammatory pain? is it reversible?
sensitisation of acute nociceptive pain due to innocuous stimuli being processed as noxious
e.g. touching the site of a burn
YES it is reversible
what is neuropathic pain?
pain caused by a lesion or disease in somatosensory nervous system, whereby neurones are sensitised even in the absence of any stimulus
what is stimulus evoked neuropathic pain?
problems with noxious stimulus amplification (hyperalgesia) or pain caused by a normal stimulus (allodynia)
what is hyperalgesia?
increased sensitivity to pain
what is allodynia?
pain induced from non-noxious stimuli
What is spontaneous neuropathic pain?
burning or tightness associated with paraesthesia, tingling, shooting or stabbing
what are the 4 mechanisms of neuropathic pain?
inflammatory mediation
altered nociceptor activity
altered spinal processing
pain processing in the brain
How do neuropeptides contribute to neuropathic pain?
released by 1st order neurones following nociceptor activation
they cause increase in local inflammation
what is the role of altered nociceptor activity in neuropathic pain?
inflammatory mediators modulate Na+ on nociceptive neurones, meaning lower threshold for AP conduction
what is unique about nociceptor nerve endings
nerve endings are free in local environment
in which rexed laminae to sensory nociceptive 1st order neurones terminate?
I to V
according to the gate control theory, which fibres ‘override’ noxious stimuli transmission in the dorsal column?
a beta fibres
what factors influence pain response?
cognition mood depression genetics context
In addition to glutamate, what other excitatory neurotransmitter is found at the synapse between the first and second order nociceptive neurones?
Substance P
through which two mechanisms does TENS produce its analgesic effects?
Closing the gate (gate control theory)
Endogenous opioid release (a delta fibres)
How should you manage acute pain? (4 concepts)
enhanced recovery
expectation management
multimodal analgesia
opioid sparing
what is meant by ‘multimodal pain management’ when treating acute pain?
use of pharmacological and non-pharmacological pain relievers to target all of the different facets of pain communication
e.g. local anaesthetics - transmission
NSAIDS - transduction
psychological interventions - pain modulation (via spinoreticulothalamic pathway)
what is the definition of chronic pain?
pain that extends beyond the the period of healing, often with no pathology, occuring for 3 or more months
what is the difference between primary and secondary chronic pain?
primary - pain is the disease itself
secondary - pain is the symptom of something else
what is physical drug dependence?
when an individual depends on a drug for normal physiological functioning
what is psychological drug dependence?
when drug use is a strong motivator of behaviour
define drug addiction
Lay term used to emphasise psychological dependency
NOT A CLINICAL DIAGNOSIS
define the term drug abuse
drug use that doesn’t conform to social norms. One can absue drugs without being dependent
how is addiction diagnosed?
how is severity of addiction measured?
when a patient identifies as having several physical/behavioural traits that relate to addiction e.g. tolerance, withdrawal
by the number of traits one displays
which region of the brain is responsible for the pathophysiology of addiction?
Nucleus accumbens
what are the three stages of withdrawal?
severe (days 1-3)
moderate (days 3-10)
mild (10-30)
explain the two different pathways to addiction
sensation seeking - those that use drugs in order to feel good
self medication - those that use drugs to cope with dysphoria in their life (often the quicker way to dependence)
what are the three stages of opioid dependency treatment?
detoxification
relapse prevention
lifestyle and behaviour change
combination of pharmacotherapy, psychological therapy and family/social support should be used to treat addiction
what receptors are found to be reduced in cocaine, alcohol and opiate addiction?
Dopamine D2 receptors
